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Revision as of 10:13, 27 February 2020
| ML19340D260 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 09/30/1980 |
| From: | PLANNING RESEARCH CORP. |
| To: | |
| Shared Package | |
| ML19340D258 | List: |
| References | |
| AMV-607, NUDOCS 8012290473 | |
| Download: ML19340D260 (190) | |
Text
{{#Wiki_filter:. __ O EVACUATION TIMES ASSESSMENT FOR THE l l DIABLO CANYON NUCLEAR POWER PLANT i t 7--.,,,
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*'*' *rJZAIICN ACI PREPARED FOR PACIFIC GAS & ELECTRIC COMPANY SEPTEMBER 1980 pcc A Planning Research Company Alan M. Voorhees & Associates Transportate. Enwronmental and Urcan Planning Consultants 2150 Shattuck Avenue
- Berkeley, California 94704 i
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l EVACUATION TIMES ASSESSMENT FOR THE DIABLO CANYON NUCLEAR POWER PLANT Prepared For: Pacific Gas & Electric Company l Septeder 1980 AMV 607 p A Plannen0 A****'en Company Alan M. Voorhees & Associates Transportation. Environmental and Uroan P:anning Consuitants 2150 Shattuck Avenue
- Berkeley, California 94704 rra ::1173:7Ac7 I::ItF;.!A :c'1 22:.2T 0 I::1:0030/':02 JIT3 IHZ 2?DC.a ;;2 :32C2 A:IC3 AC2
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l i i ! PROLOGUE i This combined report presents the results of two study phases conducted to assess the evacuation times of various zones surrounding the Diablo Canyon Nuclear Power Plant. The first study phase considered a modified 10-mile boundary surrounding the site, while in Phase II l the distance was extended 12- to 18-miles to include the area known l as the "Five Cities". At the conclusion of the Phase II analysis it was not felt necessary to modify the Phase I report based upon the added input from this j second cycle of effort. Consequently, the Phase II report was l written to follow in sequence with the expanded analysis area. The l conclusions presented at the end of the Phase II report j take into account both phases of study. Although these conclusions tre broader in scope than those reached at the end of Phase I due to the larger area studied, the results presented at the end of the initial study still apply to that particular evacuation boundary. ! Finally, Appendix A was added to address, in the light of both study phases, questions regarding evacuation times for designated l sub-areas within the overall evacuation boundary. Because the documents combined under cover in this report were produced separately, each has been page-numbered individually. However, for the eanvenience of the reader, the table of contents and list of figures and tables for each section have been printed in blue to facilitate locating each individual document. The major sections are as follows: e Phase I Report: Modified 10-Mile Boundary Including Morro Bay, San Luis Obispo and Avila Beach. (97 pages) I e Phase 11 Report: Approximate 12- to 18-Mile Boundary Including Morro Bay, San Luis Obispo and the Five Cities. (59 pages) e Appendix A: Evacuation Times for Sub-Areas within the Evacuation Boundary. (9 pages)
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. PHASE I REPORT l
4 i f i e i . EVACUATION TIMES ASSESSMENT STUDY I~ FOR THE 4 DIABLO CANYON NUCLEAR POWER PLANT i i I I 5 s Modified 10-Mile Boundary Including Morro Bay, San Luis Obispo and Avila Beach t 0 i e i l
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i TABLE OF CONTENTS _P. age. 1 I. Introduction and Overview 4 II. Area Characteristics 4 A. Topographic Features 6 B. Climatic Conditions 10 C. Infrastructure 16 III. Emergency Planning Area 16 A. NRC Requirements 19 B. Evacuation Analysis 23 C. Affected Jurisdictions 24 IV. Population, Institutions and Vehicle Trip Generations Within t.te Evacuation Area 24 j A. Residential Population and Employment Centers 23 B. Car Ownership and Vehicle Generation 31 C. Institutions 36 D. Recreational Facilities 39 5 V. Evacuation Operation Concept 39 A. Criticai Evacuation Time Period 42 B. Implementation Agency Action Steps 45 C. Action Steps by Car-Owning Population 52 D. Action Steps by Non-Car Owning Population 54 VI. Evacuation Routes 54 A. Roadway System 66 B. Natural Hazards and Alternative Routes 76 VII. Evacuation Time Estimates 81 A. Analysis Methodology 96 B. Evacuation Scenarios C. Summary and Conclusions l l l i
i i i LIST Or TABLES fage 111-1 Description of Evacuation Analysis Zones 21 IV-1 Estimated Dwelling Units and Population 25 By NRC Zone - IV-2 Estimated Dwelling Units and Population 26 By Evacuation Zone i IV-3 Estimate of Automobiles Used for Evacuations 29 IV-4 Estimated Vehicle Generation of Local and 33 Convalescent Hospitals
- IV-5 Summary of Estimated Number of vehicles 38 By Analysis Zone VI-l Local Evacuation Routes by Zone 60 VI-2 Uncongested Evacuation Travel Times 62 VI-3 Average Capacities / Hourly Volumes per Lane 64 VI-4 Summary of Typical Seismic Hazards for Bridge 74 Structures VII-l Capacities of Critical Screenlines 78 l
1 11
LIST OF FIGURES Page I-1 General Area hap 3 II-l Hilly Regions and Flood Plains in the Evacuation Area 5 11-2 Wind Diagram 3 II-3 Street Classification System 11 II-4 Study Area Utility Lines 14 III-1 10-Mile Radius and Evacuation Boundary 17 III-2 NRC Zone Description 18 III-3 Evacuation Analysis Zones 20 IV-1 School Locations 32 IV-2 Hospitals, Convalescent Homes and Other Special Generator Locations 34 IV-3 State Beaches / Paris and Regional Parks 37 V-1 Development of Evacuation Curve 46 V-2 Generation of Evacuation Curves 49 VI-l Evacuation Through Routes 55 VI-2 Local Evacuation Routes 59 VI-3 Structures Freeway / Expressway on Evacuation Route 72 ~ VII-l Critical Portals and Screenlines 77 VII-2 Demand Capacity Analysis 80 VII-3 Scenario Al Traffic Volumes 83 VII-4 Scenario A2 Traffic Volumes 84 VII-5 Scenario B1 Traffic Volumes 85 VII-6 Scenario Al Delay and Final ~ Leaving Time 86 VII-7 Scenario A2 Delay and Final Leaving Time 87 VII-8 Scenario B1 Delay and Final Leaving Time 88 e Y iii
- 1. INTRODUCTION AND OVERVIEW Purpose and Obj ectives This report contains the results of an Evacuation Times Assessment Study conducted for the areas surrounding the Diablo Canyon Nuclear Power Plant in San Luis Obispo County, California. Evacuation times were estimated for various zones and sectors around the plant starting at "zero" time which represents the sounding of the Early Warning. (Siren) System which is cur-rently being considered for installation by Pacific Gas and Electric Com-pany (PG& E) .
The objectives of the Evacuation Times Study can be summarized as follows:
- To obtain the most recent information on resident population, special institutional facilities (e.g. hospitals, educational and correctional institutions, etc.), and recreation and beach visitors within the designated evacuation area. ,
- To evaluate the existing roads in the area relative to their capability to carry the traf fic loads generated by an evacuation.
i e To estimate the time that tid be required to evacuate all in-dividuals f rom within the te /,nated evacuation area including the identification of potenti t delays due to inadequate road capacities and adverse weather conditions.
- To provide recommendations for selective and staged evacuation in order to prevent traffic congestion and to minimize the expo-sure of departing individuals to health hazards.
Evacuation Boundary Current Federal guidelinet-1/call fer an emergency planning ares consisting of a 10-mile radius from the plant. However, for practical notification and evacu-ation purposes and to avoid bisecting communities, the evacuation boundary 1/ " Criteria fer Preparar. ion and' Evaluation of Radiological Emergency Response Plans and Preparedness in Support of Nuclear Power Plants", U.S. Nuclear Regulatory Commission, Jaauary, 1980. 1 __,g_ ,,
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was extended beyond the 10-mile radius to follow more describable topographic and jurisdictional boundaries. Figure 1-1 illustrates this des-ignated evacuation boundary as well as the 2-mile, 6-mile 1/ and 10-mile radius from the Diablo Canyon nuclear facility. Reflecting the prevailing wind directions and topographic characteristics of the area, three sectors radiating from the plant were determined as also shown in Figure I-1. While these sectors represent a slight variation from the current Federal Guidelines which call for 90' sectors.between the 5- and 10-mile radius, ' the selected 67.S* sectors are found to be more practical and identifiable for use in an emergency situation. The designated evacuation boundary'shown in Figure I-l is identical to the boundary utilized for PG&E's Early Warning System with the exception of the Five-Cities area to the south of San Luis Obispo. Evacuation times for the Five-Cities area (Arroyo Grande, Pismo Beach, Grover City, Shell Beach and Oceano) will be determined subsequent to this analysis and presented as an appendix to this report. Report Contents Chapters II, III and IV of this report describe the area characteristics, emergency planning areas and the identification of the area population respectively. Chapter V contains the various action steps involved in an actual evacuation while Chapter VI deals with the evacuation routes. Finally, Chapter VII . presents estimates of evacuation times for various i sub-areas for good weath'er as well as for adverse wind and weather conditions. 1/ A 6-mile radius, rather than S-mile, was utilized to maintain consistency with earlier evacuation planning ef forts. 2 1
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- 11. AREA CHARACTERISTICS A. Topographic Features The Diablo Canyon Nuclear Power Plant site is located on a coastal terrace and is surrounded by approximately six miles of steep, brush-covered mountain ridges and deep canyons known as the Irish Hills. These hills contain a
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1 Access to these canyons is limited: many of these canyons are served by a combination of public and private 2-lane paved roads and circuitous unimproved j eep trails. These hilly areas are illustrated in Figure II-1. To the north beyond the Irish Hills, the Los Oscs Valley extends from the. City of Morro Bay to the City of San Luis Obispo and is bounded to the east by the hills of the Los Padres National Forest. The hills and large State Parks and Military Reservations in the area are some of the reasons why the present population within an approximate 10-mile vicinity of the Diablo Canyon Nuclear Facility is rather small. The development of the area is chiefly confined to the Los Osos Valley region. Development growth project-ions for 1990 are limited to " infill" conditions in still undeveloped areas in the Los Osos Valley region 1 / and no or little additional development is projected for the hill areas. l l l
- 1. San Luis Obispo Traffic Circulation Study. Wilbur Smith & Associates.
May 1979. 4
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- B. Climatic Conditions Precipitation The evacuation study area, with a climate characteristic of the central
' California coastal region, has small diurnal and seasonal temperature variations. During the months of May through September, the dry season, the rainfall is infrequent due to the Pacific Anticyclone, located off the California coast, which prevents Pacific storms from entering the state. During this time when surface winds are generally from the northwest, a high frequency of fog or low stratus clouds associated with a strong low-level temperature inversion is typical. This period is also characterized by its moderate to strong daytime winds and its weak nighttime off-shore drainage winds. From November through March, or the winter season, the Pacific Anticyclone moves southward weakening in intensity, and allows the Pacific storms to enter California. During this 5-month period, the area receives 80 percent of its average annual rainfall of 16 inches. The rainfall is usually accom-panied by strong southeast winds associated with storm systems. Winds and Air Movements In many areas the coastal mountains, which extend in a general northwest ! to southeast direction along the coastline, are more likely to affect the wind direction than the prevailing circulation. This range of mountains is indented by numerous canyons and valleys each with its own land-sea breeze regime. In valleys and canyons, entering winds are controlled by the local terrain features. However, where there are no gaps in the coastal range l and the winds are forced along this barrier, the wind speed is increased and the wind direction variation decreases. This results in increased turbu-lance and vertical mixing under inversion. Thus emissions injected into this - coastal regime are transported and dispersed by a complex array of land-sea 6
breezes in both horizontal and vertical planes. Aside from these localized micro-climates certain regional wind directions exist which influence the selection and use of potential evacuation routes. Figure II-2 illustrates the direction, speed and frequency of winds at the Diablo Canyon plant site. As can be seen, the prevailing winds are in the north-westerly direction, occuring about 407. of the time at average wind velocities of 15.5 mph. Temperatures The average annual temperature of this area is about 55*F, although under extreme conditions temperatures may range from a high of 100*F in the summer to a low of 25*F in the winter. The maximum summer temperature of 85*F and the minimum vinter temperature of 35*F are exceeded only one percent or the time. Fog Conditions Within the evacuation study area there is a year-round-occurrence of fog During the summer months, fog is associated with the on-shore flow of
- . marine air. During the winter months, fog conditions form within the one--
i two day period following a significant rainfall when tt:e stable air is mixed with the moisture of the Pacific storms. Fog conditions usually occur i during the late night and early morning periods, and although this fog is l l a convec; ion fog and not the Tule fog associated with the central Califor-l nia valley, it can restrict visibility at times. In 1979, there were 88 l occurrener , of fog conditions which resulted in visibility of 1/4 mile or less, distributed over the year as follcus: I' l/ National Weather Service phone conversation diarch 31, 1980
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C. Infrastructure i Transportation Network Most of the transportation demand in this area is served by highways, with Highway U.S. 101 as the major arterial (see Figure II-3). It runs along a note.h-south corridor connecting San Luis Obispo to Paso Robles and eventually San Francisco to the north, and to Pismo Beach and eventually Los Angeles to the south. Being the main carrier of through-traffic, U.S. 101 is a four-lane f acility at partially freeway and partially expressway standards. The freeway sections are limited access divided highways while the expressway segments may include at-grade intersections. Another main arterial is State Route 1, which diverges from U.S. 101 in San Luis Obispo and extends in a northwesterly direction to Morro Bay and up the coast. Within the study area, it is primarily an expressway consist-ing of four lanes. In addition to these two main highways, there are several parallel routes which are of relatively minor significance, but which can be used as al-ternatives to the principal arterials. Both State Route 227 and Orcutt Road connect San Luis Obispo with Arroyo Grande to the south (see Figure II-3) . Parallel to Route 1 is Los Osos Valley Road, which could serve as an alternate route for people travelling away from Morro Bay. The facilities mentioned above are basically arterials which extend radially from San Luis Obispo. Other components of the transportation network are l numerous collector roads and the urban street systems. Transit Public transportation in the area is provided by San Luis Transportation, Inc., a county-wide transportation company serving San Luis Obispo, the 10
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northern coastal communities and the south county area. The companys' fleet consists of 15 buses, three 45-seat, six 25-seat and six 21-seat. In the city of San Luis Obispo there are three fixed routes on which buses operate at one-hour headways. The natural gas-powered vehicles have a seating capacity of 25 passengers each and operate from 7:00 a.m. to 7:00 p.m. on weekdays, and from 9:00 a.m. to 5:00 p.m. on weekends and holidays. The l north coastal line connects downtown San Luis Obispo with the Morro Bay /Los Osos/ Baywood Park area. Using 45-passenger diesel buses, the system operates with two-hour headways. There are also two special shuttle services in operation: one between downtown San Luis Obispo and Cuesta College, and the other between San Luis Obispo and Cal Poly. These shuttles run at two-hour intervals on school days with minimal service on non-school days, using 45-seat buses. The South County Area Transit (SCAT) provides service between the communities .I of Pismo Beach, Grove" Ci'.y, Arroyo Grande, and Oceano. There is no link to San Luis Obispo. The vehicles used are 25-seat coaches, which operate hourly on weekdays between 7:30 a.m. and 5:30 p.m.1/- In addition to the local public transit system, several other modes serve the area; Greyhound Lines operates along U.S. 101 with connections both to the north and south; Yellow Cab and Five Cities Taxi operate taxi services in the area; and there are several local van programs which cater to elderly and handicapped persons. Pipelines The network of pipelines in the study area includes those for water, sewage, natural gas, and oil. There are presently two major water transmission lines l l serving the area. One runs between Lopez Canyon Reservoir and a terminal I reservoir near Arroyo Grande, where the water is then dispersed to the South 1/ SCAT does not own thesa buses; contract service is provided by San Luis Transportation. l ~ l . I i 12 l
Ccunty cc== unities. The other line links Santa Margarita Lake to the San Luis Obispo Whale Rock Reservoir and treat =ent plant. La addition, various distribution lines and local service lines provide connections to the users. Si=ilarly there is a network of sewage lines from the custo=ers to the treat-ment plant, and a =ain line which transports the treated se. age for dispersal in the ocean. Natural gas is supplied to the area frc= two directions. The Scuchern California Gas Company line parallels U.S. 101 as 1: approaches the study area fr = Santa Maria. A second gas line, which supplies the PG6E Morro Bay generating plant, enters the area frc= the northeast. There are several ocean oil ter=inals at Port San Luis (near Avila Beach) and in Estero Eay (near Morro Bay). Fro = these terminals oil is transpo ted through pipelines to and frcm various processing plan:s in the state. Power Lines Overhead power trans=issicn lines criss-cross =uch of :he study area because of the proxisity of the :vo PG&E generating plants. Frem the Morro Say Fossil Fuel Plant lines extend to the northeast. east, and southeast. The Diablo Canyon Diant is the origin of two transmissien line ccrriders, ene heading northeast and the other heading east frc= the site. Another type of line is an inter-regional telecc==unication cable. which generally parallels U.S.101. In addition, a transcen:inental line e=erges from the ocean near Los Osos and parallels Los Osos Valley Road to the sain terminal f acility owned by Pacific Telephone & Telegraph. These latter facilities are all underground. If a major earthquake were to coincide with an energency situatien at the power plant, all large underground crossings of sain evacuatien routes should be inspected i==ediately. Similarly, the aerisi power lines, if dislocated 13
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III. EMERGENCY P!.ANNINC AREA Federal guidelines fc r emergency response plan development for fixed nuclear f acilities recommend a protective action area around the facility of up to a 10-mile radius to protect the population against direct radiation exposure . However, unique topographic feat :res and population concentratiens of the actual area initially require a minimal evacuation radius that goes beyond the designated 10-mile area. To define the designated radius evacuation area for the Diablo Canyon Nuclear Power Plant, the following criteria were established.t e The designated area must encompass as a minimum the recommended 10-mile radius area as specified in the Federal guidelines. e The designated area must be concisely identifiable and readily comprehensible to allow for effective public broadcasting of information and guidance during an emergency event requiring area evacuation. e The perimeter of the designated area must avoid major irregularities to maintain rationality and credibility of the designated area, Lhile avoiding an imposition of potential evacuation of major population groups well beyond the 10-mile radius. The designated evacuation study area boundary, shown in Figure III-1, includes the Cities of San Luis Obispo and Morro Bay as well as a northern portion of the City of Pismo Beach. A. NRC Requirements The study area was first divided into sub-areas using the alphanumeric sector and zone designators developed by the Nuclear Regulatory Commission (NRC). Each 22 1/2 sector-is described by a letter and the zone (or distance from the facility) by a number. Figure III-2 illustrates these study area subsections. In order to facilitate regional and nation-wide comparisons between nuclear facilities, the NRC zone system was used to summarize certain types of statistics such as population. The NRC zones were" not used in the actual evaluation of evacuation times.
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- Table III-1.
In general, the analysis zones represent traffic shed areas from which evacuation traffic would drain using a specific road or highway to reach the regional freeway network. In addition, these zones have describable boundaries and can serve as the basis for selective and staged evacuation if required. This zone system has been used throughout the evacuation times assessment study. I 19 y -y-- g- --$ - tvg- y- -f -r' -. - * - sy- ' "
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Table 111-1 DESCRIPTION OF EVACUATION ANALYSIS ZONES Analysis Zone Limits (Clockwise from North) I - N. )brro Bay City Limits North Morro Bay - State Route 41
- Pacific Ocean II - State Route 41 South Morro Bay - Ridge of Bernardo, Motatains (north of U.S. Huy. 101)
- S. Morro Bay City Limits (excluding Morro Bay State Park Penninsula)
- Morro Bay-Pacific Ocean III - Morro Bay City Limits Los Osos - U.S. Highway 1
- Camp San Luis Obispo itilitary Boundary
- 35. 0 sector line (from PG & E Plant and approximately intersects the Los Osos Valley Road /Turri Road intersection
- Northern boundary of Montana de Ora State Park
- Pacific Ocean IV - Montana de Oro State Park Boundary Montana de Oro - 35 . 0 sector line
- Pacific Ocean V - Camp San Luis Obispo Property below Camp San Luis Obispo U.S. Highway 1 VI California Nan's Colony Califomia Man's Colony l VII - Zone V (Southern Limit) l Foothill - O'Connor - U.S. Highway 1 U.S. Highway 101 Imaginary Boundary f rom the U.S.101/
Marsh Street interchange to the Foothill /Los Osos Valley Road inter-section.
- Los Osos Valley Road /Turri intersection
- 35.0 sector line 21
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m Analysis Zone Limits VIII - Zone VII (southern limit) Laguna Laka - U.S. Eighway 101 .
- Imaginary Boundary connecting Indian Knob, the Irish Hill Radio Beacon and Mt. Stony 35.0' sector line IX - Zone VIII (southern limit)
San Luia Ba7 - US Highway 101
- Imaginary line from US 101/ Monte Dead interesection to Diablo Canyon Nuclear Power Plant
- Zone IV (eastern limit)
- Zone III (eastern limit)
I - Zone II (southern limit) Avila Beach - US Highway 101
- Spyglass Road
.Facific Ocean II
- California Polytechnic Institute Cal Poly and Vicinity
- San Luis Obispo Campus
- San Luis Obispo City Limits
- U.S. Highway 101
- U.S. Highway 1 III U.S. Righway 101
- San Luia Ohispo City Limita Central San Luis Obispo
- Orcutt Road (with an imaginary extension to the U.S.101/Marah Street Interchange XIII Zone III (soutbern limits)
South Higuera - Imaginary line south to Indian Knob Imaginary line from Indian Knob to '
- approximately 2500' south of the U.S.
101/Higuera Interchange U.S. Highway 101 XIV
- Zone XII (southern boundary)
- Imaginary line through Islay Hill Edna and Southern Pacific R.R. Line Imaginary line through approximately 1500' south of Broad Street 6 SSP RR to Indian Knob Zone XIII (eastern limit)
XV - Zone XII (southern boundary) Squire Canyon - Imaginary line from Indian Knob to U.S. l 101/ Spyglass Road Intersection 22 l 1
g Affected Jurisdictions The evacuation study area is entirely within San Luis Obispo County. This area includes the Cities .of San Luis Obispo and Morro Bay as well as part of Sunset Palisades in the northern section of the City of Pismo Beach. In addition, this area includes the unincorporated developmer.ta of Baywood Park, Los Osos, Cuesta-by-the-Sea, and Avila Beach and other pockets of development. The following list contains the distances of these comunities from the Diablo Canyon Power Plant site: Port San Luis 6.5 miles Avila Rameh 7 miles Los Osos/ Baywood 7 miles Les Osos Valley 3 miles Morro Bay State Park - 9 miles Sunset Palisades . 9 miles Laguna Lake 10 miles Morro Bay 10 miles Pisao Beaed/ 12 miles San Luis Obispo 12 miles Grover City 1 15 miles Arroyo Grande 1 16 miles Oceano 1/ 17 miles i l l 1/ To be analyzed later. l l l l 23
l l IV. POPULATION, INSTITUTIONS, AND VEHICLE TRIP GENERATION WITHIN THE EVACUATION AREA A. Residential Poaulation and Employment Centers In order to accurately assess the . amount of time needed to evacuate the designated study area, estimates of both the population and of the number of dwelling units by evacuation analysis zones were required. These estimates were derived by using census irformation and ferecasts of the population and number of dwelling units in the study area 1/ and by distributing them into analysis zones. The county and incorporated city population and dwelling unit estimates were furnished by local governments. These were obtained by updating census data from building permit applications, building demoli-tion applications, and augmented with vacancy rate and househo,ld-size assumptions. In preparing the final estimate used for the study this information was analyzed for trends since the 1970 federal census and projected to July 1980. An additional straight-line projection to 1985 was done to indicate short-term growth. The population figures used in the analysis inccrporate a zero percent vacancy rate and therefore exceed county estimates which include vacancies of 30 percent or more in many coastal yacation communities. This was done to consider a hypothetical " worst-case" situation in which a summer time population peak could exist. The distribution into analysis zones was aided by the use of aerial photographs, United States Geological Survey quadrangle maps, and field surveys. Estimates of the population and of the number of dwelling units are shown by NRC zones in Table IV-1, and by evacuation analysis zones in Table IV-2. As can be seen, the total estimated population, as of July 1980, in the study area is about 63,500 persons in 25,700 households. Projections for 1985 call for an increase to about 77,200 inhabitates living in 31,000 households. Using 1970 l data, it is estimated thte 60 percent of the population live La urbani:eo ; areas and the remaining 60 percent live in rural areas.2/ I 1/ Information provided by San Luis Obispo County and the Cities of San l Luis Obispo, Morro Bay, and Pismo Beach. 2/ U.S. Census Survey,1970. 24 l
l l Table IV-1 ESTIMATED DWELLING UNITS AND POPULATION RY NRC ZONES NRC Zones Number of Population 1 Dwelling Units 7/80 7/85 7/80 7/85 QRAF 1-2 Diablo Canyon 3 3 5 5 RAB 2-6 Montana De Oro 13 14 35 37 CDE 2-6 Irish Hills 11 12 23 25 EF 2-6 Deer Canyon ! - - - -- RAB 6-10 Los Ooos 4801 5778 11728 14116 CDE 6-10 Laguna Laka 1746 2158 4937 6123 EF 6-10 Avila Beach 485 524 917 993 RAB 15 Morro Bay 4784 4979 8900 9194 CDE 15 Greater slo 13865 17551 36953 46732 TOTAL 25708 31019 63498 77225 1/ Does not include group quarters 2_/ Ranchland adjacent to Diablo Canyon power plant access road 25
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l Table TV-2
- ESTIMATED DWELLING UNITS AND POPULATION BY EVACU.tTION 20NE9 i
l Evacuation Zones Number of Population 1/ Dwelling Units 7/80 7/85 7/ B0 7/85 i I N. Mocro Bay 2157 2245 4004 4136 , II S. Morro Bay 2746 2858 5096 5264 t III Los Osos 4691 5662 11554 13936 IV Montana De Oro 8 9 15 16 t V Camp SLO - - - - l j VI Calif. Men's Colony - - - - l VII N. Los Osos Road 2664 3364 6952 8772 VIII Laguna Lake 2098 2663 6034 7663 IX San Luis Eay 97 105 189 206 X Avila Beach 483 523 911 987 i XI Cal Poly & Vicinity 1775 2261 4616 5878 XII Central SLO 6819 8683 18890 24052 i i XIII South Higuera 1298 1648 2881 3657
, XIV Edna 822 947 2203 2501 XV Squire Canyon 50 51 15 3 157 l
TUTAL 25708 31019 63498 77225 l t 1/ Does not include group quarters; includes population indicated as dwelling unit population in census reports estimated with a 0% vacancy rate. 26 i i
As can be derived from Table 17-1, the current (July 1980) esti=ated popu-i lation distribution by distance from the Dishio Canyen plant is as follows: I j Number ! Within 2 miles of plant 5 0.0% Within 2-6 miles of plant 58 0.1% , Within 6-10 miler of plant 17,582 27.7% i 3eyond 10 niles of plant 45,653 72.2%
- Total 63,499 100.0%
As employment patterns indicate, the largest concentration of workers is . in downtown San Luis Obispo, which is the County seat as well as the County's regional center for marketing and financial enterprises. Ap-proximately 65 percent of all workers in San Luis Chispo live in San Luis Obispo with another 20 percent living in unspecified outlying rural areas.1/ l, t i i-i I I l I 1/ San Luis Obispo Regicnal Transportation Study. Phase II Technical Report JHK 5 Associates, DAW Inc. November 1974. i 27 v*v e--- w , c ,-e- , .-me. noe,~--we<w. ~-->v---~e - - +<e-m m s,----ow~re,w>ge._+ ,,--mww-r-,,-~ .-s,,w,- > - - - - ,--o- x, m.,w r sam e wt --+-
l 4 l ^ B. Car Ownership and Vehicle Generation the dwelling unit estimates for the fif teen evacuation zones were used j to estimate the number of vehicles that each zone would generate during an evacuation. To do this, data from the 1970 U.S. census were applied i to the dwelling unit estimates to determine the number of one, two, and three-or-more car owning households in each zone whether urban or rural. ! This information was found to be as follows: , i 4 Percentage of Car-owning Households in 1 j San Luis Obispo County Household Type Urban Zones Rural Zones One-car Households 49.5% 55.2% Two-car Households 32.5% 27.6% Three-or-more-car House-holds 9.0% 9.3% Non-car-owning House-holds 9.0% 7.9%
, TOTAL 100.0% 100.0%
In order to estimate the number of vehicles that would leave a particular zone , the car-owning household characteristics had to be converted into i vehicles. Thus, all of the one-car households were assu:ned to generate one car, while 50 percen: of the two-car households would generate one car and the remaining 50 per:ent would generate two cars. All of the three-car households we re assumed to utilize two cars for evacuation purposes. Application of these assumptions to the number of 1980 households results in just under 3C,000 residential-based vehicles that are estimated to leave the study area during an evacuation as shown in Table IV-3. The following two sectic ts, Institutions and Recreational Facilities, will discuss the special traf fic generators in the study area. These generators j would require special attention for evacuation purposes and would in some cases add to the total r.imber of vehicles. It should be pointed out that j 28
_ -. . - - _ . . . . = . . - _ - .- .. _ _ = - _ . . Table IV-3 ESTIMATE OF AUTOMOEILES USED FOR EVACUATIONSb Evacuation Zona Nussbar of Number of Vehicles Number of Zone 'Designa- Households Used for Evacuation Non-car-tion owning (Urban / Households Rural) I U 2157 2502 194 i II U 2746 3185 247 III R 4691 5441 371 i W R 8 9 1 V 1 _ _ _ VI R - - - 1 VII R 2664 3064 210 VIII U 2098 2433 189 ) IX R 97 112 8 X R 483 555 38 I XI U 1775 2058 160
- XII- U 6819 7909 614 XIII R 1298 1506 103 XIV R 822 954 65 XV R 50 57 4 TOrAL 25,708 29,785 2,204 l
l 1/ Does not include group quarters l l t 29 i
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although these special generators would be evacuated, not all of them produce trips during the actual time when the population is leaving the area. At a high school, for example, students and employees would be expected to , y return home prior to evacuation. Since these people are accounted f or by virtue of being " assigned" to a dwelling unit, these trips were deleted from the evacuation traffic stage of the analysis to avoid double counting. On the other hand, beach and park users were added to the evacuation traffic totals under the assumption that they could, as a maximum, be entirely comprised of non-residents or visitors. The scope of this study did not include development of the actual evacuation operations for these special facilities. However, the potential vehicle gene' ration from these generators was considered in order to see if an identifiable amount of delay time would be caused by their presence. Table IV-3 also indicates that there are approximately 2200 non-car-owning households in the evacuation study area which will require special attention when developing an evacuation plan.1/For the purposes of this study, it was assumed that non-car-owning persons would be picked-up at ce rtain designated collection points or, in case of elderly and non-ambulatory citizens, be transported directly from their homes to designated reception centers outside the evacuation area. For conservative reasons, little ride-sharing was assumed in cases of an emergency, although .ht fact rides with neighbors and friends may occur. Section C below describes the evacuation action steps by the non-car-owning population in more detail. 1/ It should be noted that since these numbers were developed from county-wide averages, these estimates are approximate. 30
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'dithin the designated evacuation area there are 29 schools including paro- . chial schools and college carpuses. De locations of these schools are l
t/
- identified in Figure IV-1.
4 4 T.a three largest edtx:ational facilities in the evacuation study area a re: e the California Polytechnic State Universt'.y (Cal Poly) e the San Luis Obispo County Comunity College (Cuesta) e the San Lui.s Obispo Senior High School , 1 l Cal Poly has an acade=ic-year student / staff population of approximately 17,900 persons, Cuesta College about 3,370 persons, and San Luis Cbispo i High School approximately 1,300 persons. [ i
- General and Convalescent Hospitals t
There are three =ajor general hospitals and four convalescent hospitals in f
- the evacuation study area. These
- medical f acilities would require special t
, attention during the evacuation process since it would requits the coordina- '
tion of staff persennel, a::6ulance service , and the relocation Of bed-confined patients to temporary :nedical f acilities 1,,cated outside the evacuation i area. Characteristics of the seven aforementioned hospitals are sher. in Table IV-4 Figure IV-2 indicates their location. l Other Institutional Generators l ne California Men's Colony, a nini=um-to-medissa security correctional c l institution, houses apprcxt:sately 2550 innates, and 1.s patrolled by about l KO guards and staf f members. At the present time, the California Men's i Colony has no evacuatica plans for its innates, so the sheltering of the inmates l i r 1 i 1/ Includes public and private schools as listed in the 1979-80 San Luis Cbispo County school directory. i 31 i
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Tahle ri-4 ESTIMAIE3 VEHICLE CINEF.ATICN OF GENERAL AND COWALESCEST ROSPl!ALS Fatilities Beds Average Ntaber Staff vehicle s of Patients Gene rated Gene ral Hospit al s l i San Luis Chispo 92 50 125 77 Sierra Vista 172 137 200 254 French 138 75 100 120 Convale seen t Hospitals Cabrille 162 NA NA NA Hacienda 163 163 100 103 Casa de Vida 99 99 50 52 Morro Bay C. Center 72 72 35 37 1/ Does not include the nu:nber of ambulance trips genwrated as these trips would not be characteristic of the general flow of traffic. These trips were derived by estimating the number of staff, out-p atient , and visitor vehicles that would be generated. 33
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A HOSPITALS $ NORSLNG HCMES i p cx E cinse sescN cenee.,Tce < taArtcr45 d i 4 l C c FIGURE JL 2 : HC$PfGLS, GNVALE6MNT HCloES - AND OTHER 6PEc!AL .'nENERATCR t.Ct'ATIONS l ( A 34
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4 i ! j would be the ' most likely.. occurrence. If the Men's Colony should be evacuated, i t this f acility would generate approximately 460 cars which includes staff l and state cars as well as visitor vehicles, but does not include about 70 buses that may be needed for the evacuation of inmates. 1 I f i Located opposite the California Men's Colony is Camp San Luis Obispo, the l National Guard Headquarters. During the sumner training months (peak l season), there are about 1100 persons on post who in an evacuation situation
! would generate an estimated 300 vehicle trips. ! i 1
The location of these two generators is shown in Figure IV-2. t i 4 I 1 i l i i I I I f ! i r l r i } a 4 4 I 35 i r 1 I ccv--~~v, m =v n - -e, ,,y. vm,we,---v+,-y--.m,m .,nr..,,, ,e n- e nv w-- www w- ,..<,--w--,neww--,w.--e-,, e-. ..mn.-.- --,--were- ,,r,-.-_ . . . - -.-v -- tm --w w a w,--w
_D . Recreational Facilities There are four major recreational facilities within the designated evacuation area: three are state facilities, and one is operated by San Luis Obispo County. The location of these recreational facilities is shown in Figure IV-3. In ' addition. there are three regional parks in the area which straddle the evacu-ation boundary. According to information and data received from the State Park Superintendent, the Labor Day weekend represents the maximum annual attendance period. On a given day during this rnree-day weekend, the following number of vehicles can be expected to be gent. rated by each of the recreational facilities: Number of Vehicles Facility Generated I Atascadero State Beach 160 Montana de Oro State Park 196 ' Morro Bay State Park 475 Avila Beach (SLO County) 600 1431 Campers, cars, trailers, and motorhomes represent the primary mode of trans- ) portation used by 99 percent of all visitors to recreational facilities in the ! area. Of the remaining 1.0 percent, 0.9 percent are walk-in risitors, and j 0.1 percent use public tranrportation. As can be seen, the beach and park visitors are quite self-sufficient in terms of transportation and would be able to evacuate with their own vehicles. i The number of vehicles generated by residential households and the special generators described above are summarized in Table IV-5. i i l l 36 l 1 i L
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Table IV-5 Summary of Estimated Number of Vehicles Generated by Analysis Zone Residential- Vehicles Added By Total Vehicles Zones Based Vehicles Special Generators Generated I 2502 160 Atascadero State Park 2662 II 3185 (37) Morro Bay convalescent Home 3185 III 5441 475 Morro Bay State Park 5916 IV 9 196 Montana de Oro State Pk. 205 i V O (300) Cdap San Luis Obispo O (1200) Cuesta College O V; O (460) California Men's Colony 200.1./ VII 3064 (52) Casa de Vida 3064 VIII 2433 0 2433 IX 112 0 112 X 555 600 Avila Beach 1155 XI 2056 5000 Cal Poly 7058 (284) Sierra Vista Hospital XII 7909 (225) Sar Luir Obispo HS 86342/ (120) French Hospital (103) Hacienda Convalescent (77) San Luis Obispo General (725) Hospital Direct Evacua-tion XIII 1506 0 1506 XIV 954 0 954 XV 57 0 57 TOTAL 29785 + 7356 = 37141 ( ) Not included in" Total" column to avoid possible double counting. 1/ Includes 200 trips for misc. farm vehicles. 2/ Includes 725 direct evacuation trips generated by hospitals 38
J V. EVACUATION OPERATION CONCEPT A. Critical Evacuation Time period The starting time of an evacuation might occur at any one of the following three time periods:
, Nighttime on a weekday or unekend
- Daytime on a weekend
- Daytime on a weekday j Each of these combinations was considered in the study with the following results: There is an essential tradeoff in any evacuation between t'he vehicle generation rate and the transportation system capacity. At one end of the spectrum, the population is rapidly mobilized, but their movement time is then determined by the transportation system capacity. On the other hand, if adequate capacity exists, the evacuation time will depend upon the ability to mobilize the population. A gray zone exists between these two extremes where both factors contribute. In general, the Daytime / Weekday case is the worst-case situation for the basic reason that a substantial evacuation delay occurs in mobilizing and assembling the family unit, fol-lowed by roadway capacity delays in leaving the study area.
Nighttime Evacuation In the event an evacuation sere necessary at nighttime, the notification process would be hampered by people having to wake up and comprehend the evacuation informaticn being broadcast. Additional time would probably be required to prepare vehicles for evacuation in the dark. Nevertheless, for I most segments of the population, the family unit would be intact at the l time of notification. Thus, a nighttime- evacuation would potentially place a demand on the transportation facilitiss at an earlier time and possibly at ( 39 l l 7
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F L a higher rate than for a daytime situation. However, excessive delays could be avoided through the use of staged evacuation, by sheltering people in
- heir 5c=es rather than having the stalled =cre vulnerably in potential traffic congestions. The total evacua:icn time during a nighttire emergency would most likely be shcr:er than for a daytime evacuation since the vast majority of people veuld already be he e.
Daytise/ Weekend Evacuation . The daytime /veekend si:uation represents a case be veen the two other situa- : tions and ::ay require scme staged evacuation in order to be orderly. In the analysis, :he sensitivity :o a sore peaked : rip generatten rate was tested which resulted in increased roadway congestion rather than in a reduction of everall evacua: ion ti=e. Daytiee/Veekday Evacuation The third analysis case selec:ed was :he daytime case where there is a considerable pre-evacuation " rush hour" period when family units are being reunited. I: vas found tha: the day / weekday case represents the worst-case situation with respect to everall avac:uation time and tha: this time period l should be utilized in determining evacuation times. In order to represent ; the wors: time of a year, car generation rates per dwelling unit were de-veloped assuming a 100 percent occupancy of structures. In additien, : rips were estimated frem beach and park areas and added to those made by resi-dents thus assusing : hat all recreatien pcpulation would come frc outside the designated evacuation study area. Finally, the state university was considered to be in session, so that the evacuation was essentially assumed to take place on an early sumer weekday daytime when both per=anent residents and visitors are accumulated in :he area. It should be noted that while the case analy:ed is somewhat of an extre=e, the overall evacua-tien time was not found to decrease significantly with a siner reduction in traffic generation. De :ise was controlled by the evacuation behavior
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of the population and a few key hottlenecks. While the population that would be present during an actual emergency may most likely be less than the maxi-mum possible, delays would be reduced, making traffic control less critical, but still necessary. However, the maximum population figure was used in this analysis, for conservative reasons. 41
B. Implementing Agency Action Steps The process of implementing the evacuation of the population within the designated area in the event of an emergency condition at the Diablo Canyon Power Plant would be expected to include the action elements summarily outlined below. Although a detailed evacuation plan was not produced concurrently with this study, the indicated steps were presumed in order to determine the evacuation times. Notificationb! The initial step in implementing the evacuation would be the notification of the public within the designated evacuation area through the sounding of sirens indicating that an emergency condition exists and that the public is to turn to radio and television broadcasts for additional information and guidance. Information Broadcasts Public information, guidance and instructions would be issued to the local broadcasting stations. The broadcast .sformation must comprise: e Notice to evacuate the area e An enumeration of the communities whose populations must evacuate o An enumeration of. the reception areas for persons requiring public shelter e Notico of the public transport facilities available and actions required by persons in need of such services e Notice of any abnormal area roadway conditions (e.g. , impassability of roadways in the case of a major flood) and guidance information to use alte rnate roads and alternate reception areas . 1/ The details of the notification system are not analyzed in this report. 42
In the analysis, evacuation time t=0 was taken as the sounding of the emergency siren system. It was further assumed that the emergency broad-cast instructions would be repeated in five minute intervals. Mobilization of School and Public Transportation The school bus fleet would be mobilized in the event that evacuation occurs while children are still at school. This mobilization task would have
- two basic components
- (1) mobilization of the bus fleet normally available to a given school district, and (2) mobilization of additional school buses j
from adjacent districts, as required to meet demand. A detailed analysis of the school busing situation was not performed in the study, although the evacuation curves developed take into account the delay caused to certain i segments of the population in awaiting the arrival at home of school children. The public transportation bus fleet would be mobilized and will likely comprise both vehicles from private contractors and from public transport agencies. Activation of Public Transportation Call-In Centers The telephone operators (either locally or at the County Emergency Operations Center) would be mobilize.1 to receive calls for public transport from transit dependent persons in rural areas and would dispatch buses assigned to rural area collection. Table IV-3 indicates an estimate of the number of non-car-owning households by zone based upon analysis of census information. I Mobilization of Controllers at Urban Center Public Transport Collection Points Traffic controllers would be dispatched to fire stations, designated as public transport collection centers, in developed areas to provide information to the public transport dependents and to aid in orderly dispatching of buses. 43
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- Mobilization of Roadway Traf fic Controllers i
1 J The state and local police force would be assigned to designated i i potentially critical locations en the area roadway system to expedite - J traffic flow. ) , I j Mobilization of Wreckers I i
*dreckers would be mobilized and assigne'd to selected key locations on
- the roadway system regardless of weather conditions. Wreckers would be
,i required to maintain system capacity by rapid removal of stalled or out-of-gas vehidas. 5 l ' i i 1 i f, EE 1 <
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C. Action Steps by the Car-Owning Population Evacuation _ Curves The calculation of evacuee departure rates leaving home is based upon i the mathematics of combining probability distributions which individually represent liklihoods of certain evacuation steps taking place within a given time af ter task initiation. Figure V-1 conveys graphically the process which takes place for those members of the population who are at work when the alarm is sounded. The height of the curve at each point indicates the percentage of the population engaged La each particular act at a given point in time. The graphs indicate how the " wave" of evacuses is spread over a larger and larger time frame resulting from a number of sequential steps that must be accomplished before the actual act of leaving the area can begin. For example , the first persons to evacuate, approximately at one h'our af ter re-ceipt of notification to evacuate,are those who very quickly grasp the evacuation notification, who are the quickest to leave work, who have the shortest driving time home and who are quickly packed once home. As a percentage, this is a very small group of people. The following sections describe in detail the individual steps which, in combination, produce the final evacuation " wave". In the study, two different movement distributions were developed to represent different classes of population. Evacuation Distribution 1, ac described below is for the working population. Distribution 2 applies to those at colleges, parks and other l special generations who do not have to return home by car prior to starting the evacuation. Public reaction to the evacuation notification and instructions would result l generally in certain action steps which are described in detail as follows: I 45
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i i Notif ication During a daytime event, nost area workers will receive the notification to evacuate at their place of work. Predicated on the assumption that the public information broadcast conumences five minutes af ter the activation of the Early Warning System (Siren), it is estimated that the entire area pop-ulation will be apprised of the broadcast information within 45 minutes. The rate at which the broadcast information is assimilated is depicted as I the " Notification" curve in Figure V-I. Its shape and range have been 1 suggested by existing studies of civil defense alerting. For analysis purposes, it was assumed that 10% of the population will become aware of the need to evacuate by time t=15, (that is 15 minutes after the. sirens sound). The peak would be reached at t=30, and all notification would be complete by t=45 minutes. In the event notification was significantly slower than indicated above, the duration time of total evacuation would be extended by the additional time required to apprise everyone. Leaving Place of Work The rate at which area workers will leave their jobs to return home to l i prepare for evacuation will be quite variable, depending upon the particular
! work environment and upon the responsibility level of the worker. It is to be expected that a large proportion of the work force will be able to leave their jobs almost immediately, quite similar to a normal departure f rom work at the end of the workdai. A number of workers, however, will require some j job "close-down" time in work situations; for example, those that involve machinery, construction equipment, or cash registers in retail sales I
establishments. In addi: ion, supervisory employees, managers, and independent business operators will generally require a greater amour.t of time to secure their pla:e of work and to assure that all employees and others on the premises have departed.
! Based in part upon generalizations from worker parking studies, a time distribyrion of workers leaving their place of work has been assumed 47
recognizing the above acted variations. This is illustrated in Figure V-I as the " Prepare to Leave" curve. Be assiumed percentage of workers leaving their place of work following eceprehension of the broadcasted infor ation begins to rise rapidly with 50*. leaving work within 10-minutes of recognition of the need to evacuate. All workers being evacuated vere assumed to be leaving work 30 =inutes following the re ce ipt of broadcast inf ormation. Se travel cine of the e=ployees from their place of work to home has been estimated by analyzing employment and co=mmuting patterns within the county. The =axi=u= trip length for work journeys in the area is esti .ated to be about 20 niles, and the most cousson trip length is esti=sted to be three to f our =11es. Ten =inutes of delay time has been added to che average travel times that are expected to occur in a nor=al rush-hour situation, to take into account the additional bunching of workers during this extreme-case rush hour. The resulting travel time curve is shown as the " Drive Home" curve in Figure V-r. In the case of college students, beach and park vf sttors and-other persons at si=ilar institutions, a different pattern wouli evolve, which would have a significantly shorter time frame. Bese groups would walk either to their dormitory, in the case of students, to a parking lot, or directly
" hone". These people are represented as Evacuation Distribution 2 in Figure V-2, whict. co= pares the scre conmaon Distribution 1 for comanuters with these other population sub-groups. (Note that the walk times are a =axistan of 35 minutec versus up to an hour for drive times.)
Of course, sone people would already be at home when the alarm is sounded. For those that belong to a family unit involving school children or workers, it was assumed that the family would not evacuate until all the me=bers were broght together, hence the Distributien 1 would still apply. On the other hand, for those persons not constrained by family, inanediate evacuation froc: the area is possible. Similarly, immediate evacuation from work is possible for those workers who co:nnute into the evacuation
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area frem cities to the north or south of the designated evacuation are a. Most of these people would evacuate before the general demand for evacuatien routes has developed. If a large proportion of the population could be directly evs.cuated, the overall evacuation time cculd be reduced. Information to accurately estimate the siae of this population group does , not exist , so for analysis purposes it was assumed to be a small percentage of total population. Thus there would be no effect upon overall , evacuation ti:ne. Preparation f or Evacuation People can be expected to react differently to any emergency situatica, ad the conditions imposing an evacuation need on the area population are likely to generata great differences in the amount of ti:ne people will spend in preparing to leave their home. In order to estimate the overall evacuation ti:se it has been necessary to attempt a prediction of time that will be needed prior to actual evacuatior.. The variations in this time vill occur as a consequence of numerous factors. Some of the more dominant fac-tors include: ; e Selecting basic necessities for those persons evacuating to public shelter areas as opposed to persms evacuating to homes of friends and relatives e Size of the family and number of children e Number of cars available e Securing animals on farms / ranches e Individual sense of urgency The predicted preparation times prior to evacuation, shown in the " Prepare to Evacuat1" curve in Figures V-1, were derived from the following population categorizations: e A mall percentage of the area households are single-person households, and this segment of the population could be expected to be highly =obile and ready to leave in 15 minutes. 50 1
i
- A larger proportion of the area residents may feel a high sense of urgency and be prepared to leave home within 30 minutes the arrival time of the worker (s).
- The largest proportion of the area residents will require some time to pack some essentials, especially in households with children, to decide on what to do with pets, to decide on auto usage in the case of mult-car houssholds and, as a result, may require 45 minutes to one hour following assembly of the family members.
- A proportion of the area population involved in farming or in conducting a business at their home is likely to require the greatest amount of time, not only to prepare for individual family member needs but to secure equipment, livestock, e tc. ,
and as a consequence, their time needs may be well in excess of one hour. Similarly, tn evacuation curve for those at the State University and others who hav+, fewer needs to care for is expressed ha Distribution 2, allowing a maximum of 45-minutes preparation time. The resulting evacuation departure curves and their derivation are shown con-ceptually in Figure V-2. It should be noted that for Distribution 1, an evacuee begins to leave at about 1:15 (one hour and fif teen minutes af ter notification) and has effectively left home by 3:00. For students, beach and park visitors and other special groups, the evacuation can begin effectively at time 0:45 minutes and the leaving is completed effectively at 2:00 hours after notification. The term " effective evacuation departure times" is used because the extreme (less than 1%) tails of the resulting probability distribution are ignored. The justification is that, in reality the sequential events are not truly independent. For example , if a worker were late in getting started at home, he would probably attempt to make up time in packing. Or if he were delayed getting home, another family member could begin preparations, etc. For these reasons, the " tail" of the curve has been assumed to appear at the 99th percentile. l 51 1
D. Action Steps by the Non-Car-Owning Population As indicated previously, the non-car-owning population in the area is esti-
- mated at 4564 persons and of this total nearly 62 percent reside in the urban centers with another 19 percent in urbanized, unincorporated areas such as Los Osos, and Avila Beach.
The single most important element in providing time efficient evacuation to transit dependents is the assembly of people at a limited number of desig-nated places for pickup by buses or other designated means. Within the urban centers this can be accomplished readily by designating the local fire stations as assembly points. A similar procedure of assembly at fire stations or at a limited selection of other locations in the rural township area would impose unrealistic walking distances of several miles in hilly terrain. For members of non-car-owning households in the rural areas, it is, therefore, proposed that these people be instructed to telephone and request bus or other transportation. As noted in Table IV-3, the number of public transport dependents in the rural areas ranges from about 500-650 with the exception of Los osos, Baywood, Cuesta-by-the-Sea, and Avila Beach. These population numbers represent about 250 to 325 non-car-owning households and therefore about 250 to 325 telephene requests for transportation assistance. For purposes of developing an evac-uation program, it was assumed that little or no ridesharing would take i place. This would also represent a worst-case situtation. I There are two basic options in the designation of telephone response centers to the requests for transportation assistance. One alt'rnative e would allocate this responsibility to the local municipality or community. The telephone response center would then logically be either at the municipal offices and would be manned by municipal employees (or persons assigned by the munici-
- pality), or the center would be at a designated rural fire station and manned similarly as.above. Contact between all local telephone response centers and the County Emergency Operations Center would be required to arrange for 52
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appropriate dispatching of buses, vans or other vehicles to effect the actual pickup of the public transportation dependents. The advantages of this alternative are: e The local municipality can designate the staff (or possibly volunteers) and provide munic.ipal cars to ferry the transportation dependents to central bus pick-up locations within the evacuation zone. e The local staff are familiar with the area and this will be of major value in locating the people requesting assistance. The second alternative would allocate the responsibility for manning a-countyside telephone response center for requests for transportation at or under the direct jurisdiction of the County Emergency Operations Center. The advantages of this second alternative are: e The areawide bus mobilization coordinator function can be merged with the telephone response center and thus permit more effective distribution and dispatching of available vehicles. e During the public information broadcast only one telephone center needs to be mentioned and thus the broadcast message content and the public action requirements are simplified. The action sequence anc bus and vehicle fleet requirements, for the evacuation of public transport dependents from urban centers and rural areas, and the evacuation of school children will require further study in developing the arca-wide evacuation plan. 53
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VI. EVACUATION ROUTES A. Roadway System Main Freeway / Expressway Links US Route 101 and State Route 1 provide the prime access links for the study area. As Figure V1-1 indicates, US 101 is a continuous route from the north to the south, while Route 1 is present only as a separate facility north of the city of San Luis Obispo and south from Pismo Beach. Route 101 has two lanes in each direction and is built to full freeway design standards with limited access at grade-separated interchanges within the County. Expressway segments, containing a limited number of at-grade crossings, are found immed-iately north of San Luis Obispo on the Cuesta Grade and through Cuesta Pass. The Cuesta Grade extends for about five miles north of the city and has a maximum grade of nearly seven percent on the last two miles of climb. Other expressway segments on US 101 are found farther north above Paso Robles and Arroyo Grande, both of which are outside the present study area. Route 1 going north begins in San Luis Obispo as Santa Rosa St, a four-lana road with wide median and turning pockets. There are frequent intersections 3 and several traffic lights in this short segment inside town. Above Highland and outside the city limits the road continues as a 4-lane expressway with infrequent rural grade crossings. Continuing north, the road is generally of expressway quality to San Simeon, except for freeway segments through parts of Morro Bay and Cayucos. Beyond Cayucos, Route 1 converts to a two lane facility with some access control. To the south, Route 1 exists between Pismo Beach and Gaviota in Santa Bar-i bara County in varying states of improvement ranging from a 2-lane non-access-controlled route to a freeway facility. The section of Route 1 in San Luis i Obispo County south to th2 Santa Barbara County line is two-lane, uncontrolled. 54
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Other Through Routes There are a number of minor routes which would provide additional capacity in the event of an evacuation of the study area. To the north, State Route 41 provides egress from the Morro Bay area. Although this road connects back into US 101 at Atascadero, this connection occurs more than 20 miles from the site. In addition, there is reception center capacity along Route 101. Thus, this link would play an important part in an evacuation of the study area. Similarly, to the south, State Route 227 and Orcutt Road would aid in an evacuation of the immediate area, although they tie back into Route 101 at Arroyo Grande, about 16 miles from Diablo Canyon. An evacuation plan will have to consider the possibility of queuing at Atascadero and Arroyo Grande, but such an effect would not change the estimated evacuation times to the evacuation boundary. Finally, there is additional capacity provided by the frontage road along Route 101 to the south of San Luis Obispo, which provides an uninterrupted link out of the study area, and which in fact ties in with the continuation of Route 1 south of Pismo Beach. This frentage road begins as Higuera St. in San Luis Obispo, east of Route 101. At the Higuera interchange with Route 101 south of the city it connects under the freeway to Ontario Rd., a parallel frontage road west of Route 101. This frontage road then continues past the San Luis Bay interchange, swings away from Route 101 and ties in to Avila Road immediately before the Avila interchange. South of that interchange, the frontage road is called Palisades Road, but is re-named Shell Beach Road immediately south of Sunset Palisades. Finally, in Pismo Beach, the frontage road intersects with Route 1 and changes its names to Price Street. Price St. leads directly onto 101, and there is no continuous frontage - road through Pismo Beach. However, at this point Route 1 is a separate 2-lane facility which continues south out of the county. It should be noted that there are several roads in various conditions of improvement leading into the hills to the east of San Luis Obispo. Although some of these roads cross the mountain ridges to the east and eventually 56
leave the area, they were not judged to be of year-round availability to the typical passenger car. Thus they were not used in the analysis. Whether or not these~very local roads should or could be used under an actual emer-gency situation remains to be determined. Interface With Statewide Highway System Route 101 serves as one of the two major north-south routes connecting the San Francisco / Sacramento region with the Los Angeles / San Diego region, the other being Interstate 5, located a considerable distance to the east in the central valley. Although an tsportant tourist route, Route 1 is of lesser importance for state-wide travel. An evacuation of the study area would necessitate closing Route 101 and St 1 Route 1 to long-distance traffic. Although the time required to evacuate the study area would not be influenced by the manner or location in which the barricading and subse-quent diversion of through traf fic took place, the through-traffic diversion would be an important consideration in an evacuation plan. To the south, numerous cross-connections exist in the Los Angeles area, the northernmost of which is State Route 126. Route 33 could also provide diversion from as far north as Ventura or Santa Barbara, and at the southern boundary of San Luis Obispo County Route 166 is available. North of the study area but within the county are State Routes 58, 41 and 46, with others located closer to the San Francisco Bay Area. A notable lack of cross connections between Route 1 and Route 101 exists between Cambria in San Luis Obispo County and Monterey, a distance of more than 70 miles. The potential operation of these cross connections beyond the study area will also be an important consideration in the routing of people to the reception centers. Destinations and Reception Points The existing county emergency plan identifies a number of short- and medium-term reception centers. These facilities would be mass-care centers to which the evacuated population would be directed. In addition, it must be 57
r * , noted that a proportion of the population would choose to find their own non-institutional solution to the problem, either by staying with a friend or relative, or seeking temporary shelter in a motel nearby, or leaving the area entirely. In determining and siting reception centers, several unique factors need to be considered. Firstly, a large proportion of homes within the study area are vacation homes. As an example, in the Baywood Park /Los Osos area, approximately 10 percent of homes are second homes. This condition exists in general for all of the coastal cities. A second consideration is the importance of the local tourism and its role in the region's economy. Under evacuation conditions, visitors to the area would generally depart to their original home, and thus not require sheltering. I ! Regardless of whether evacuees are bound for a reception center or will assume personal responsibility for their continued sheltering, the travel patterns would be similar, since potential reception sites will most likely be located along major north-south highways. Among the sites which may be used are the Santa Barbara County Fairgrounds in Santa Maria or Vandenberg Air Force Base in Lompoc, both located in Santa Barbara County to the south, or the San Luis Obispo County Fairgrounds in Paso Robles or Camp Roberts near San Miguel, both north of the study area. Camp Roberts, in particular, has an estimated long-term capacity of 20,000 persons. t Local Evacuation Routes Within the city limits of San Luis Obispo and Morro Bay there are numerous local streets which ultimately connect to the' major evacuation through-routes. In the unincorporated portions within the study area, there are generally fewer routes available that connect with the major freeway links. l Local routes of evacuation importance are highlighted in Figure VI-2. Table l VI-l indicates by evacuation analysis zone which routes and alternative routes, if any, are available. Shed Areas and Uncongested Travel Times l Table VI-2 lists uncongested travel times between the population crntroid 58
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Table Vl-1 LOCAL EVACUATION ROITIES BY ZONE Zone Prime Routes Alternate Routes I San Jacinto Street various local streets Main Street Ironwood Avenue IISI Main Street various local streets Morro Bay Boulevard South Bay Boulevard III1 South Bay Boulevard none Los Osos Valley Road IV Pecho Road unimproved r Clark Valley g d to V Route 1 - direct access O'Connor Way VI Route 1 - direct access VII Foothill Road Los Osos Valley Road VIII Los Osos Valley Road Foothill Road Madonna Road IX See Canyon Road to Prefumo Valley Roao2/ San Luis Bay Road X Avila Road Cave Landing Road XI Highland Drive various local streets Foothill Boulevard Grand Avenue California Boulevard XII Marsh Street Toro Street Broad Street California Boulevard Ocos Street Grand Avenue Monterey Street Johnson Avenue etc. XIII3/ Higuera Street various local streets Madonna Road Prado Road l 1/ Significant risk of loosing all evacuatica routes in flood or heavy rain conditions 2/ Alternate route may be impassable to regular passenger cars in rainy season 3_/ Significant portions of zone may be isolated by flood condition 60
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Table Vl-1 (cont . ) LOCAL EVACUATION ROUTES BY ZONE l Con tinue d ( XIM Orcutt Road Tank Farm Road Edna Road Id San Luis Say Road Monte Road , e a i i i i 4/ Road currently closed at Sunset Palisades (locked gate) 5/ In extreme flood conditions may loose all access i n i el
Table VI-2 UNCONGESTED EVACUATION TRAVEL TIMES Local Street Access Freeway Route Eva u on Zone Distance Speed Time Distance Speed Time Time (Min.) (Miles) MPH (Min.) (Miles) MPH (Min.) I 0.8 20 2.4 1.6 35 2.7 5.1 II 1.2 20 3.6 3.5 35 6.0 9.6 III 4.0 30 8.0 4.8 35 8.2 16.2 IV 10.6 25/30 23.8 4.8 35 8.2 32.0 V 0.9 20 2.7 10.5 35 18.0 20.7 VI 0.7 20 2.1 12.2 35 20.9 23.0 VII 2.0 25 4.8 1.9 35/30 3.6 8.4 VIII 4.6 30 9.2 6.6 45 8.8 18.0 IX 3.6 30 7.2 2.4 45 3.2 10.4 X 2.7 30 5.4 1.2 45 1.6 7.0 XI-Rt. 1 .6 20 1.8 15.5 35 2.6 28.4 US 101 .7 20 2.1 .6 30 1.2 3.3 XII-US 10lN 1.6 20 4.8 0.4 30 .8 5.6 Rt. 1 1.5 20 4.5 16.1 35 27.6 32.1 . US 101S 2.3 20 ; 6.9 8.2 45 10.9 17.8 XIII-US 10lS 1.2 30 2.4 5.0 45 6.7 9.1 US 10lN 1.7 30 3.4 2.9 30 4.7 8.1 XIV 3.2 35 l 5.5 N/A N/AM N/A 5.5 XV 0.9 25 2.2 2.4 45 3.2 5.4 1/ From each zone to designated evacuation boundary 2_/ Via Route 227 62
f of each analysis zone and the study boundary via the shortest routing. Since, in general, evacuation behavior and roadway congestion determine , evacuation times rather than the free travel time, these results do not represent actual evacuation times. They do provide an indication of the relative accessibility of the various analysis zones to the cordon line, and give a measure of local road versus freeway travel for each zone. Road Capacities Table VI-3 indicates the assumed roadway capacities based upon facility type and location. The terms " urban" and " rural" denote different levels of ' capacity based upon roadway geometry, frequency of intersections, volumes of cross traffic, and similar factors. It should be noted that these are
! not necessarily maximum possible capacities, but rather represent a prac-tical capacity at still acceptable levels of service, although the freedom of maneuver would oe somewhat restricted. The figures in Table Vl-3 are on a per-lane basis and were applied to critical links in the transportation network.
In the analysis, special attention was given to the capacities of the free-vay and expressway facilities. Although hourly capacities of 2,000 vehicles and more per lane have been observed on urban freeways, such values would not be realistic under the prevailing conditions in the study area. The l reason for this is that, when flow is above 1800 vehicles per lane per hour 1 (vph) a minor disturbance such as a sudden breaking of a vehicle can cause a congested condition to occurr. In the case of Route 1 leaving San Luis Obispo, the pr.sence of numerous intersections calls for a further reduction j in carryinr, capacity, and for analysis purposes, a capacity of 1500 passenger cars per lane hourly was selected. For the non-freeway stretches of Routes , 1 and 101 heyond the urbanised area of San Luis Obispo, however, the 1800 vph figure was used since these segments are mostly access-controlled and- ' because the few at-grade intersections that do exist would generate rather l tittle traf fic during an evacuation. l 63 1
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i Table VI-3 AVERAGE CAPACITIES HOURLY VOLUMES PER LANE Location 1 Functional Category Urban Rural Local Collector 1200 1500 (2-lane facility) Arterial Street 1500 1500 (4-lane facility) Freeway / Expressway 1800 1800 (4-lane facility) Ramp 1200 - 1500 i 1 1/ Distinction to be based upon frequency of intersections 2/ Only if geometrics are constrained, otherwise 1500. 64
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In case of an evacuation, it would become necessary to close Foute 101 through the Cuesta Grade and Pass north of San Luis Obispo to heavy trucks. The reason for this would be to provide as much capacity as possible to the evacuation traffic. The seven percent grades prevailing on this freeway segment could have a considerable capacity-reducing effect if heavy truck traffic were allowed during the evacuation peak. i l I i 65
1 l B. Potentia] Hazards and Alternative Routes There are a number of natural hazards which could effect the performance of the evacuation by causing disruption of the road system. The primary ! focus of this analysis is to identify and define the range of problems which could occur rather than to place a probability or measure of risk on these various incidents and their quantitative effect on the evacuation times. An exception is the case of a rainstorm without flooding of evacuation routes, for which an estimate is presented in Section VII. The Safety Element of the General Plan of San Luis Obispo County1 / lists i four groups of hazards: fire, flooding, geologic hazard and radiation. An additional concern not included among those is the infrequent but severe occurrence of coastal fog which could affect U.S.101 between the AJi'.a Beach and Arroyo Grande exits and Route 1 north of Morro Bay. Fire With regard to' fire,the Safety Element addresses both urban and wildland fire. The presence of a major fire of either category would immediately place additional burden upon those charged with protecting the safety of the public. In the case of an urban fire, it is most likely that evacua-tion delays would be caused for only a small segment of the population , since it would be unusual for an urban fire to close one of the main evacuation routes. ! Concerning wildland fires, the Safety Element indicates that the most I fire-prone areas of the ccunty are (1) near Santa Margarita, (2) west of Nipomo, and (3) adjoining Nacimiento Reservoir. Although none of tnese 1/ Safety Element, San Luis Obispo County, June 1976 66 i
m _ are within the study area, Route 101 passes through Los Padres National Forest on its climb through Cuesta Pass out of San Luis Obispo. However, the roadway is located at the lower elevations of the fire-prone Santa Lucia Range and probably would be less af f ected by a potential forest fire than higher elevations. Route 41 also crosses Los Padres National Forest, but the alignment is at the bottom of a valley parallel to Morro Creek. Flooding Figure 11-1 indicates the general locations in the study area where flooding may occur. The streams in the county that could impact an emergency evacuation by flooding are most likely San Luis Obispo Creek and Morro Creek. In terms of number of persons affected, a severe flooding of the San Luis Obispo Creek system appears to be the major flood threat to an evacua-tion. Although floods have been recorded in the area since 1848, the storm of January 18, 1973 caused the most devastating flood ever reported in the San Luis Obispo Creek drainage area. Flood waters raced through the downtown area, and the California Department of Transportation reported that Route 101 was rendered unusable at two places due to flood waters. A mudflow across the Cuesta Grade blocked the road for one hour, and flooding in the vicinity of Los Osos Valley Road closed the freeway for four hours. Reports by city and county officials indicate that the en-tire town was isolated, as flooding was also said to have interrupted the southeastern road connections near the airport, while Route 1 was said to be out of service due to a rockslide north of the study area. In response to the 1973 flood, a study was conducted by the U.S. Army Corps of Engineers for San Luis Obispo Creek and 4t* tributaries in the-vicinity of San Luis Obispo. The study concluded that a 100-year flood (the " intermediate regional flood") would have a flood stage lasting two hours, while the " reasonable upperlimit" flood or " standard project flood" (with no frequency specified) could persist for up to four hours. 67
The 100-year flood would ef fectively cut of f the following evacuation routes: at. San Luis Obispo:
- Route 101 south of San Luis closed due to flooding, (Ontario Road fronting on Route 101 to the west may open, but could not be reached by any significant amount of the population due to extensive flooding at Prefumo Creek and the San Luis Creek confluence near Los Osos Valley Road and Route 101).
- Route 101 north of the toen closed at the northernmost inter-change, Monterey Street.
- State Route 1 closed at Santa Rosa Street and Foothill.
In question are the two remaining two-lane routes out of town, Route 227 and Orcutt Road, both of which are crossed by creeks not included in the Corps of Engineers study. It would appear trat Route 227 would probably , also be closed, but that Orcutt Road would remain open. However, flooding. within San Luis Obispo would make it very difficult to rcach this route. Local flooding under the 100-year condition would close Los Osos Valley Road, Madonna Road, and entirely innundate the stretch of Higuera Street from its connection with the: freeway south of town up to Santa Rosa Street. In addition, flooding along Higuera would extend across town to Pismo Street between Broad and Santa Rosa. Within the county, San Luis Obispo Creek would flood the San Luis Bay crossing, eliminating direct access to Route 101 from Squire Canyon. Avila Road would remain open. The Safety Element indicates that 100-year flooding of Morro Creek would be expected to remain within the established stream bed. However, no def-inite answer was given to the question of whether the Route 1 bridge across this stream could be blocked by a severe flood. 68 a
3 Not =entioned in the Safety Element is the " twin trestles" crossing of South Say Boulevard over Chorro Creek and an unnamed creek in the city j of Morro Bay. The frequent blockages of this route would tend to place it within a ten-year, or even less, flood zone. It has oeen reported that the flooding out of South Bay Boulevard has been accompanied with the closure of Los Osos Valley Road between Baywood Park and San Luis Obispo, thus isolating Baywood Park and Los Osos. If this were to happen during a plant emergency, evacuation during the course of high water would be impossible, and means of temporarily sheltering the population would have to be found. This would require sheltering up to 11,600 persons. In summarizing the flood scenario, the following points should be made: Flooding would affect substantial numbers of people within the study area, and would isolate even a greater number. Evacuation of flooded areas would take place in any event, but not necessarily in the same manner as a general evacuation such as that caused by poisonous or radioactive gas release. Furthermore, 100-year flooding would dis-cupt all major evacuation routes in the vicinity of San Luis Obispo and Los Osos/ Baywood Park. On the other hand, the flood stage should last only a few hgurs (two hours for the 100-year flood). Thus evacua- - tion will best be accomplished by temporary sheltering followed by ex-pediant removal of debris from critical routes. An additional concern would be bridges which may be washed out, requiring the identification ' of alternative routes. Due to the uncertain 11es involved, a reliable time estimate could not be incorporated in this study. However, it would appear that evacuation times could be at least doubled under these condi-tions. Other Effects of Heavy Rainfall
~
Another source of road closings due to rainfall is from landslides, rockslides and mudflows. As was mentioned above, the Cuesta Grade was briefly closed in the January 1973 storm due to a mudflow across the' 69
pavement. The concrete dividing wall which is currently being constructed in the median may prevent such an occurrence from affecting all four lanes, leaving the possibliity that reverse-direction operation may overcome the problem. Rockslides have b'een a frequent cause of problems for State Route l~to the north outside of the study area. There is some evidence of falling rock along Avila Road, and there are a number of other locations where steep slopes adjacent to evacuation routes warrant inspection. If an evacuation should occur during heavy rain falls, the positioning of earth moving equipment at these slide-prone locations and exp' editions clearing of the obstacles should be considered. Earthquake The Safety Element of the General Plan of San Luis Obispo County addresses o a number of possible hazards due to seismic activity including: active faulting, ground shaking, settlement, rising ground, soil liquefaction, landslides, tsunamis and seiches. The report dismisses seismic seiches out of hand as a problem.in the county, and also concludes that a tsunami would only be of concern should it occur at high tide. The rising ground condition is a very localized situation which was not fully analyzed at the time the plan was published. With regard to the remaining major earth-quake hazards, the Safety Element and the accompanying Seismic Element lay out in general terms the type of problems to be expected in various locations within the county. It would be very difficult, if not impossible to evaluate the likely amount,of damage and evacuation delay time caused by a major earthquake to localized segments of the urban areas. On the other hand, it is possible to look for potential problems along the major evacuation routes. 70
While a detailed analysis of slope stability, settlement / liquefaction potential, abutment, retaining wall, and bridge deck failure for the evacuation route was beyond the scope of this study, the consultant has cataloged by structural type the major bridge structures along the freeway / expressway facilities leading out of the evacuation area. In addition, possible alternative routes have been identified and ana-lyzed. Alternative Routes Due to Bridge Failure Figure VI-3 shows an inventory of bridge structures by type and configura-tion (overcrossings, undercrossings and freeway-carrying decks). Also indicated on the chart are available alternative routes, some of which involve using the " wrong" side of the road until the median can be re-crossed to the proper side. From this inventory, the following find-ings can be drawn:
- Route 1 Northbound: Most individual bridge failures could
'oe bypassed locally. One exception is the freeway bridge over Main Street in Morro Bay, for which there is no con-venient alternative route. Traffic would have to exit from below the bridge, travel over local streets to enter.on the wrong side of the road at the off-ramp, and cross back over at the first median break. The other potential problem bridge is the high structure over Chorro Creek near Camp San Luis Obispo. The alternative route is circuitious and travels
- over rural two-lane roads.
- Route 101 Northbound: If any or all of the bridges failed along that route, the San Luis Obispo city streets could serve as a bypass. The loss of a few key structures could cause tremendous disruption to traffic within the city, however.
71
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Route 101 Southbound: Most of the bridges have alternative routes available in the form of interchanges, ramps and the frontage road. At the Higuera Street crossing, freeway traffic would have to utilize wrong-way operation except if a fence were knocked down and temporary fill placed in a drainage ditch. Traffic could then continue down the westerly adja-cent frontage road and bypass the bridge. 4,lso indicated in Figure VI-3 are numbers placing the structures into broad classification categories which tend to increase in structural vulnerability, all other factors (scale, joints, foundation and others) being equal. The accompanying Table VI-4 contains general comments about the type of fail-ures potentially to be encountered in a major earthquake. Dam Failure Another area of concern in case of an earthquake is that of dam safety. The Safety Element lists three main potential dam hazards due to an earth-quake: failure due to surface rupture along et fault, failure due to earth shaking and overtopping due to landslides into the impounded waters. The report notes that surface rupture is not a significant hazard within the county. With regard to landsliding, the study concluded that Whale Rock reservoir and Rhigetti Reservoir had significant hazard potential. The Safety Element indicated that, as far as failure due to earth shaking is l concerned, the strength of major dams had not been determined. The report did note, however, that only Whale Rock, Rhigetti and Lopez Reservoirs would be expected to cause a major hazard should the'; fail. Of these potentially hazardous dams, Rhigetti is closest to the study area. Flooding would be , expected to follow Corral de Piedra Creek, which crosses Orcutt Road and Route 227 southeast of the study area. With a water contents of 560 acre-feet, this dam is one of the smaller ones of.the dams in the county. Lopez Reservoir is larger at 51,000 acre-feet, but it is considerably outside i I 73 l
Table VI-4
SUMMARY
OF TYPICAL SEISMIC HAZARDS FOR BRIDGE STRUCTURES BEHAVIOR OF BRIDGE CATE- (MODERATE TO STRONG BRIDGE TYPE GORY GROUND MOTION) DAMAGE BOK CULVERT 1 Fill Subsidence Road Offset in Fill SHORT SINGLE Fill Subsidence Road Offset in Fill i SPAN BRIDGE i Shift at Bearing 2 Span offset at Bearing I" (lateral and/or Vertical
%?& W"'
SHORT MULTIPLE SPAN BRIDGE , Abutment Subsidence Span Offset at End bearing 3 Colu=n/ Pier Failure Span Shifted or Collapsed or Subsidence at Intermediate Bents I' iW'y .- 5 ,y w- ~ d '
'EDIUM MULTIPLE SPAN 3 RIDGE Abutment Subsidence Span Offset and End Bearing 4
Shif t at Bearings Span Shifted or Collapsed
'weer-e l
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the study ar ea. Flooding from that dam is expected to affect the Arroyo Grande Valley although there is no indication whether or not Route 101 would be affected. Probably the most catastrophic dam failure would be at Whale Rock, a 40,000-acre foot reservoir which is located directly above Route 1 at Cayucos. Its rapid failure would most likely destroy about one-third of the town of Cayucos, and probably make Route 1 impassable in the process. i Radioactive Contamination The drifting of a radioactive plume over an evacuation route or the con-tamination of a certain sector surrounding the plant would also con-stitute reason to select an alternative route. On the basis of recorded j wind patterns (see Figure II-2), it is most likely that the affected area would be the coastal zone from Avila Beach to the Five Cities area. j Without the availability of any detailed information of the probability of such an occurrence and its dose rate, it was assumed, as an alternative scenario, that all southerly routes out of San Luis Obispo were unusable due to radioactive hazards. This scenario as well as two others are des-cribed in Chapter VII-B. 75 I (
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VII EVACUATION TIMES ESTIMATL3 A. Analysis Methodology Critical Screenline Analysis Di order to dete rmine the likely evacuation times and delays a " critical screenline" analysis was performed. At key points of the evacuation route system certain screenlines or testing points were establishad for comparison of the projected traffic demand and the existing roadway capacity. Fi;ure VII-l shows the location of these screenlines and their individual critical road portals. Some of the screenlines are located where the major evacuation routes cross the designated evacuation boundary while others were placed at strategic points inside the study area. Table VIl-1 contains the estimated 15-minute capacities for the critical screenlines and for individual roads. These capacities are based on Table 111-3, but have been converted to 15-minute increments for analysis purposes . Vehicle Queueing and Delay Evacuation delays were calculated by the following method: Critical screenlines were examined in a 15-minute interval for queueing buildup based on a comparison of capacity and evacuation demand as expressed by the evacuation curves described in Chapter V, ab ove . Using the assumption l l I of first-in/first-out servicing of vehicles, the resulting delay times (if any) were calculated by time frame. In order to properly reflect the level of detail of the analysis, delay results were summarized in 15-minute increments. In doing so, all queueing time estimates were generally rounded up to the next higher 15-minute amount to reflect the uncertainties of travel demand distribution, highway incidents, and other intangibles. I ! Figure VII-2 conceptually illustrates at a single critical portal how a roadway capacity limitation leads to a queue and hence delays for the inter-mediate and last vehicles. The demand curve is produced by multiplying 76 1
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Table VII-l CAPACITIES OF CRITICAL SCREENLINES 15-Minute Screenline Road (s) Capacity Pe rcent 1 Los Osos Valley Rd. 300 2 South Bay Blvd. 375 3 Route 11 750 4 Route 101 900 75 Frontage Rd.1/ 300 25 1200 5 Route 1 9 00 70 Route 41 375 30 1275 6 Route 101 900 7 Orcutt Rd. 375 50 Route 227 375 50 750 8 Route 101 900 75 Frontage Rd ! 300 25 1200 1/ Capacity reduced by Cross-Streets. 2/ Assume 300 due to capacity loss at in te rchanges 78
the appropriate evacuation distribution curve by the number of total vehicles using the particular portal. This results in the number of arrivals at each point in ti:ne. In practice , arrivals are grouped into 15-minute segments by creating all cars within the 15-minute period as though they arrived at the end of the interval. The 15-minute arrivals were then compared to the 15-minute capacity to determine the queue, if any. As is shown in Figure VII-2, as the demand increases, departures also increase until capacity is reached. At that time (t ) departures remain constant while a queue develops (shaded zene). Although the peak demand occurs at t,,x , the queue continues to build until time t when 3 the arrivals drop below capacity. From time t t 3 '4, arrivals continue to decrease, but the bottleneck continues to operate at capacity until the queue is dissipated. The screenline analysis described above was applied to several different evacuation scenarios as suunnarized in the next report section. 79
( 3 PEAK PEMArip - ' i 3 4 l @'% i OJE06D [ e veagME At as= t 9
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B, Evacuation Scenarios In order to evaluate likely evacuation times for different weather conditions and dif ferent degrees of traffic control, three hypothetical evacuation scenarios were analyzed. These are: e Scenario A1: Minimum-Control Evacuation e Scenario A2: Route 1- Controlled-Access Evacuation e Scenario Bl: Southern-Routes-Unavailable Evacuation These three scenarios resulted from the examination of a larger number of potential operational alternatives and represent distinctly dif ferent situations. For each of these scenarios, estimates were prepared of the total traf fic volumes generated. .on the various major transportation links. At critical screenlines, the likely vehicle delays and the times of the last car leaving the screenline were determined. Intermediate as well as gateway screenlines, located at the evacuation area boundary, were utilized. Figures VII-3 through VII-5 show the estimated traffic volumes to be evacuated over the various evacuation routes for each scenario. The volume split between different highway f acilities at a given screenline was dete rmined in proportion to the available traf fic carrying capacity of each roadway. Although some localized unbalanced loadings may occur in an emergency situation, it can be expected that, in general traffic will divert from congested routes to those with available capacity. Such optimum use of the available road system can also be assisted by local traffic control and monitoring of the traffic build-up during the evacuatier.. Figures VII- 6 through VII- 8 contain the resulting traffic delays at the screenlinesand their likely duration and time of occurrence. Also, the time of the "last car leaving" is indicated. As was described earlier, 81
4 1 i these times were calculated using the evacuation demand curves combined with capacity limitations, and incorporate travel times to the screen- , line points. This explains the longer evacuation times of the last car at t I j the gateway screenlines. l The following sections describe each evacuation scenario in more detail j and summarize the conclusions in each case. i l
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Scenario Al - Mini:aum-Control Evacuation In this scenario it was assumed that no or little control was imp sed on the evacuees. All routes would be open to traffic and evacuating vehicles would distribute in a natural. unconstrained manner except for diversion to lesser used roads as congestion builds up on the freeways. At the gateway screenlines, the initial evacuation demand appears at about t=l:00, that is one hour af ter sounding warning sirens. At t=1:30, delay is established and persists to about t=4:00 at the Route 1 gateway, t=2:30 at the Route 101 North gateway and t=3:00 at the Route 101 South gateway. (See Figure VII-6 ) . Traffic leaving San Luis Obispo will distribute itself l in proportion to facility capacity using a total of five different road facilities. Although a trip from San Luis Obispo in southerly direction on Route 101 would be closer to the nuclear plant initially the large capacity of the freeway and its frontage road with little upstream loading makes this an attractive evacuation route. At the same time, the proximity of the San Luis Obispo evacuation zones to Route 101 north means that cars using that route will be able to clear the evacuation boundary faster than cars travelling south. The time of the "last car out" would be t=3:15 and c=3:45, respectively as shown in Figure "II-6. The worst congestion and delays in this scenario would occur for vehicles leaving the Baywood /Los Osos area. Because of extreme competition for the l
- single northbound lane of South Bay Boulevard towards Route 1, it would l be advantageous in ter
- ns of overall time for some vehicles to leave this area by traveling east on Los Osos Valley Road. The assumed directional split betwaen these two roads takes into account the following factors: driver f
l experience of relative delay, drivers' perception of overall travel time l required to reach the boundary, the relative capacity of the two facilites, and local traffic control efforts. 'ahile the last car out of Los Osos l to the east leaves earlier than the last car northbound, that car will l only reach the evacuation boundary at approximately the same time as the northbound vehicle. As can be seen, South Bay Boulevard to the north will experience vehicle delays of up to 60-75 minutes causing a considerable 89 l t
back-up. Even Los Osos Valley Road to the east, delays of up to 30 minutes would occur. To overcome these delays, a staged evacuation for the Los Osos/ Baywood Park /Morro Bay areas should be considered. While a staged evacuation would not necessarily reduce the total evacuation time needed, people would be retained longer in their homes instead of on congested streets. This would reduce the likelihood of secondary delay effects of stalled vehicles resulting from engine overheating and running out of gas. The delays at the Route 1 North gateway, in the order of up to 60 minutes, would also be reduced by retarding the evacuation of Morro Bay in f avor of Los Osos. Another major problem with this scenario is the potential congestion on Route 1. There is not adequate capacity on this facility to handle traf fic from both the northern zones (Los Osos, Morro Bay) and San Luis Obispo. Consequently, Route 1 would back up towards San Luis Obispo starting at the Morro Bay gateway screenline, about ten miles northeast of San Luis Obispo. The following is an illustration of what would most likely happen to an individual driver leaving San Luis Obispo: The driver would experience some delay in San Luis Obispo getting access to and leaving town along Route 1. However, this delay would dissipate outside - the city limit where the capacity Lncreases. Because of this, the road would appear locally as an attractive evacuation route. Af ter having traveled as much as five miles down the road however, the driver would be f aced with congestion in a stop and go operation and a freeway back-up which would range five to seven miles in length and involve up to one-hour delays. Due to these considerable delays, Scenario Al was judged unacceptable and a modified Scenario A2, involving access control of Route 1 in San Luis Obispo was examined as described below. The expected delays at the remaining screenlines and gateways of Scensrio Al would be quite acceptable at about 15 minutes. Since the underlying
- evacuation assumptions reflect the presence of all residents, a maximum accumulation of outside visitors, and conservative roadway capacities, the 15 minute delay could actually be less.
l 90
Scenario A2 -- Route 1 Controlled Access Evacuation In this scenario, evacuation delays on Route 1 would be avoided by closing the northbound lanes of Route 1 for a certain time to allow Los Osos and Morro Bay traffic to evacuate first. While use of this route would still be allowed for ccmmuters returning home to the Los Osos/Morro Bay area, road blo'c ks would be set up and non-local traffic would be diverted until later in the evacuation. The analysis indicates that Route 1 should be closed at about t=l:00 and re-opened at approximately t=2:45. At that time, sufficient road capacity will be available on Route 1 in the Morro Bay area to allow a speedy evacuation of San Luis Obispo traffic. 1 Obviously, the closure of Route 1 will increase the evacuation delay in the San Luis Obispo area. However, the overall evacuation time for this area is not noticeably changed and the last car will still be able to clear the evacuation boundary at about the same time as in Scenario Al, at about t=3:15 (U.S.101 North and Southern routes) and t=4:00 (Route 1 North ) (See Figure VII- 7) Congestion on the other available evacuation routes leaving San Luis Obispo would increase somewhat due to the temporary closure of Route 1 (30 to 45 minutes of delay as compared to about 15 minutes for Scenario A1). Scenario A2 has the effect of improving considerably the situation on Route 1 in Morro Bay, resulting in reduced delay times of about only 15 minutes as compared to 60 minutes under Scenario A1. The reduction in traffic congestion also will enable the "last car out" to cross the evacuation boundary at approximately 4:00, that is 15 minutes earlier than under the minimum-control scenario. l The delay situation at the Route 101 South gateway would not be appreciably dif ferent in the two scenarios. The last car would leave at about t=3:45, 3 hours and 45 minutes from time of notification. A similar reduction in traffic congestion could be achieved by a delayed evacuation start of the City of San Luis Obispo. In that case , notification ot
to evacuate would be held back by about 3 hours, again, allowing Los Osos and Morro aay traffic to clear out first. In such a case, the overall evacuation time for San Luis Obispo residents would amount to about 5-6 hours (instead of 3-4 hours) although delays at any evacuation screenline would be 15 minutes or less. A delayed San Luis Obispo evacuation start, however, might be difficult to enforce due to the large number of routes and freeway ramps in the area. In addition, valuable roadway capacity on 1 the southerly evacuation routes (U.S.101 South, Highway 227 and Orcutt Road) would remain underutilized initially. It is felt that Scenario A 2, involving the temporary closure of Route 1 as described above, represents a more practical solution than the delayed San Luis Obispo evacuation. A further evaluation of the pros and cons of staged evacuation by zones should, however, be conducted as part of the preparation of the evacuation operations plan at a later time. Scenario A2 would not be able to reduce the considerable evacuation delay projected for South Bay Boulevard out of Los Osos. Potential solutions for this problem are:
- 1. Onc-way operation in outbound direction on one or both routes leaving the arca starting at about t=l:45. This would make it rather difficult or impossible for cmergency and other official evacuation veheiles to enter the area.
- 2. Widening of the critical roadway sections of South Bay Boulevard (e.g. the Twin Bridges) to three or four lanes from the current two lanes.
- 3. Use of shoulder lanes on South Bay Boulevard so that two lanes can be operated in the outbound direction and one lane in the inbound direction. This potential measure may have to be combined with traffic controls at intersections, deployment of auto wreckers and
- tow trucks to remove parked and stalled cars and bottleneck monitor-ing in order to increase roadway capacity. Inbound traffic at bottlenecks (c.g. the Twin Bridges) may have to be restricted for certain intervalc during the peak of the evacuation.
92
- 4. Staged evacuation of Los Osos subsections to achieve a more orderly and epread-out traffic flow out of this area. The staging would be accomplished in accordance with available road capacities.
If two lanes were available on South Bay Boulevard in the outbound direction chrough any of the first three actions above, the evacuation congestion delays could he reduced by about one-half from a typical delay of 60-75 minutes to anout 30 minutes. In addition, "last car out" times would be improved by about 45 minutes to t=3:00. In sumary, Scenario A2 is considered to be the preferred evacuation scheme producing the least congestion delays and shortest overall evacuation times under good weather conditions. 4 93
Scenario B1: Southern-Routes - Unavailable Evacuation 1 This scenario assumes that evacuation would occur during heavy winds in the prevailing north-westerly wind direction. (See also Figure II-2 ). Under chese circumstances the radioactive plume could possibly reach the southern i evacuation routes prior to the peak of the evacuation and thus render the use of these routes undesirable. It was, therefore, assumed that all traf-t fic would be directed toward US 101 North and Route 1. Obviously, this scenario assumes a " worst-case" situation since the highway capacity would! ! be reduced to about 50% of that available for Scenarios Al and A2. f Figure VII-8 portrays the resulting evacuation traffic volumes on the remain-ing available routes. In order to keep anticipated traffic delays in San Luis Obispo at a minimum, all Los Osos/ Baywood Park traffic would be routed via South Bay Blvd. only. I As can be seen in Figure VII-8 , considerable delays and congestion would occur on the two freeways ranging frce one hour in the Morro Bay area to up to two hours in the vicinity of San Luis Obispo. Maximum potential de-lays on South Bay Blvd. would be on the order of one and one-half hour. It should also be noted that not only are the actual delays larger for individ-ual vehicles but the delays would also affect a larger number of persons over a longer time period. A staged evacuation scheme would have to be implemented to reduce traffic delays to acceptable levels and to minimize potential hazardous exposure of persons in cars. I
- The "last-car-out" times for Scenario B1 would range between approximately t
l five and six hours, or about two hours longer than for the earlier scenarios. If the projected congestion would be allowed to develop, there is a potential for secondary delay effects caused by stalled vehicles and accidents. These l secondary effects, although not quantifiable at this time, would tend to delay i the overall evacuation time for the last vehicle even further. However, under l a staged evacuation, the last-car-cut time would not be appreciably longer, and potentially even shorter, than the five-to-six hours quoted above. 94
Adverse Weather Impacts on Evacuation Times An estimate of the ef fect of heavy rains or fog on the projected evacua-tion time was obtained by reducing road capacities to 80% of those that would prevail under good-weather conditions. If visiblity is restricted by rain or fog, traffic would still continue to move, but at a slower speed. ( A study of traf fic flow under rain conditions showed the capacity of a freeway facility to be reduced to between 81 and 86 percent of normal, dry-weather capacity ). In order to simplify the analysis, a reduction in total trips was not made, even though it is doubtful that a peak vacation period would coincide with heavy rains. For some zones, vacation homes acco unt for 30 percent or more of the population. Beach and park trips would also most likely not occur during an adverse-weather period. If compared to dry-weather Scenario A1, the Minimum Control Evacuation. . the rain scenario shows a maximum of 75 minutes of queueing delay, with the "last car out" leaving at t=5:00 hours, while the corresponding Scenario Al values are 60 minutes delay and t=4:15. Thus a 20 percent reduction in road capacity due to adverse weather results in about an 18 percent increase in overall evacuation time, and in a 25 percent increase in queueing delay. 1/ E. Roy Jones et al. , " Environmental Influence of Rain on Freeway Capacity," Highway Research Record 321, 1970 95
t C. Summary and Conclusions The following conclusiona can be drawn from the evacuation time analysis: e The designated evacuation boundary comprising an area of up to 10-12 miles trom the Diablo Canyon Nuclear Power Plant has a population of about 63,500 persons living in 25,700 households. During an evacuation, this population would generate about 30,000 vehicles. e The total time needed to evacuate the population from the designated area is estimated to be in the range of three to four hours. This applies to normal good-weather conditions and assumes availability of all existing roads and highways. e If the routes leading south out of the area would be unusable l due to a radioactive plume, travelling in southeasterly dir-ection, the total evacuation time would be increased by about two hours to five to six hours.
! e Similarly, adverse weather conditions with restricted visibility due to heavy' rains and fog could increase the total evacuation time to between four and five hours. (All routes in use.)
e From among the three analyzed time periods into which an evacuation could fall (nighttime, daytime on a weekday, day-time on a weekend) the daytime / weekday situation is likely to produce the longest total evacuation time. e L2 general, Route 1 would experience relatively greater traffic congestion than Route 101 due to its lower capacity. For the recommended evacuation scenario, delays of up to 15 minutes would exist on Route 101 and up to 30 minutes on Route 1. e Regardless of when an evacuation would occur, some degree of overall traf fic control will be desirable in order to avoid the severe congestion on Route 1 which would be caused by San Luis Obispo and Morro Bay /Los Osos/ Baywood evacuation traffic. Such controls should include closing of Route 1 to evacuation traffic from San Luis Obispo until such a time when most traffic from Los j Osos and Morro Bay has lef t tne evacuation area. e Localized bottlenecks caused by lack of adequate road capacity in the Los Osos/Baywcod area would require a high degree of local traffic control to insure an orderly evacuation. Spe cific operational strategies such as a staged evacuation within !: tis zone or a 2-lane northbound operation of South Bay Boulevard l should be considered to avoid delays and congestion during an evacuation. l 96 l i - - - , .- . . . --- .. - . . . . ,
i 1 ( e The total evacuation time would not be significantly affected by staged evacuation but persons would be sheltered in their homes rather than being exposed to potential health hazards in their cars. o Depending upon the location of reception centers, the degree of local traffic control and other factors, additional bottleneck situations may develop along Route 1 north of Cayucos outside of the designated evacuation boundary where fewer highway lanes are available. However, adequate " storage" capacity exists along the 4-lane segment to allow traffic to clear out of the evacuation area. e Evacuation times for the Five Cities area consisting of Grover City, Arroyo Grande, Pismo Beach, Oceano and Shell Beach will be analyzed separately and incorporated into this report as an appendix at a later time. In addition, it is understood that details of an Evacuation Operations Plan will be developed jointly by the County of San Luis Obispo and PG & E. l 97
). . - ___. .. .. e i ie 1 J i : PHASE II REPORT FIVE CITIES ADDENDUM l i 4
,l i i
I 1 ! EVACUATION TIMES ASSESSMENT STUDY i FOR THE f >
; DIABLO CANYON NUCLEAR POWER PLANT +
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I i e i ' Approximate 12- to 18-Mile Boundary Including Morro Bay, San Luis Obispo and the Five Cities r I i 5 4 1 i. I 2
. , . ,, . . , . . . . . . _ . . , . . . _. _ , _ , _ _ . . . , . , _ - . - . . . . . . . . _ . - . . . _ . , . _ . . - - . . . . - -. , _ . . - . _ , . . - - . . . . . . , _ , - . ~ .
TARLE OF CONTENTS
- f. a age, I. Introduction and Overview I II. Area Characteristics Topog aphic Features and Development 4 A.
4 B. Transportation Network 7 III. Emergency Planning Area Population, Institutions, and Vehicle Trip Generation 10 IV. Within the Evacuation Area A. Residential Population and Employment Travel 12 Pat te rns 15
; B. Car Ownership and Vehicle Generati,n C. Institutions 17 D. Recreation and Tourism 20 E. Summary of Total Evacuation 24 V. Development of Evacuation Curves 26 VI. Evacuation Routes 29 A. Roadway System 29 36 B. Potential Hazards and Alternate Routes 39 VII: Evacuation Time Estimates 39 A. Evacuation Scenarios B. Overall Evacuation Planning 53 Findings and Conclusions 58 C.
I l l l l \ \ l 1 i
LIST OF FIGURES faggt I-1 General Area Map 2 II-l Street Classification 6 III-1 lo-Mile Radius and Evacuation Boundary 8 III-2 NRC Zone Description 9 III-3 Evacuation Zones 10 IV-1 Hospitals and Convalescent Homes 19 IV-2 School Locations 21 V-1 Generation of Evacuation Curves 27 . VI-l Evacuation Through Routes 30 VI-2 Local Evacuation Routes 33 VI-3 Study Area Utility Lines 38 VII-l Critical Portals and Screenlines 4 VII-2 Scenario A2 Traffic Volumes 43 VII-3 Scenario B1 Traffic Volumes 44 VII-4 Scenario C Traffic Volumes 45 VII-5 Scenario A2 Delay and Final Leaving Times 46 VII-6 Scenario B1 Delay and Final Leaving Times 47 VII-7 Scenario C Delay and Final Leaving Times '8 l l ( LIST OF TABLES l i III-1 Description of Evacuation Analysis Zones 11 j IV-1 Estimated Dwelling Units and Population by NRC Zones 13 IV-2 Estimated Dwelling Units and Population by Evacuation Zones 14 IV-3 Estimate of Authomobiles Used for Evacuation 16 IV-4 Estimated Vehicle Generation of General and Convalescent 18 i Hospitals I V-5 Recreational Trips 23 IV-6 Summary of Estimated Number of Vehicles Generated by Analysis 25 Zone V I-1 Local Evacuation Routes by Zone 34
,VI-2 Uncongested Evacuation Travel Times 35 VII-l Capacities of Critical Screenlines 41 11 l
.i d
id 'i 0 I. INTRODUCTION AND OVERVIEW This report contains the results of an evacuation times assessment study for an expanded study area surrounding the Diablo Canyon Nuclear Power Plant and is intended as an extension of the previous study whi;h considered only a ten-mile radius to the southeast of the plant.1 / The former study included the City of San Luis Obispo, the City of Morro Bay and the unincorporated cities of Baywood /Los Osos and Avila Beach. In this study phase, the southeast boundary is extended to comprise the incorporated cities of Pismo Beach, including Shell Beach, Grover City and Arroyo Grande as well as the unincorporated area of Oceano. This added area is known locally as the "Five Cities". Both the Phase I study area and the expanded Phase II boundary are shown on Figure I-1. Although the results of this phase of the study are explained within this , document, reference is made to the previous report for general information and technical detail. In addition, the inclusion of the Five Cities within i the study area has resulted in certain findings which differ from those I ! previously reported in terms of the overall evacuation scenario. l As in the earlier phase, evacuation times were estimated for various zones and sectors starting at "zero" time representing the sounding of the Early Warning (Siren) System which is currently being considered for installation by Pacific Gas and Electric Company (PG&E). In this phase of the study, the overall evacuation boundary is essentially the same as the boundary con-templated for the early warning system. l 1/ Alan M. Voorhees & Associates, " Evacuation Times Assessment Study for the Diablo Canyon Nuclear Power Plant," April 1980. i l 1 l
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The objectives of this Addendum can be summarized as follows: e To obtain the most recent information on population, institu-tional facilities (such as hospitals and schools), and recrea-tion and beach visitors within the expanded designated evacus-tion area known as the Phase II boundary.
- To evaluate the existing roads in the area with respect to their capability to carry the traffic loads generated by an evacuation.
- To estimate the time that would be required to evacuate all per-sons from within the designated evacuation area and to identify potential delays due to inadequate road capacities and adverse weather conditions.
e To provide recommendations for selective and staged evacuation in order to prevent traffic congestion and to minimize the ex-posure of departing individuals to health hazards. Report Contents Following this introductory chapter, Chapter II describes area character-istics for the Five Cities where. they differ from those mentioned in the Phase I report. Chapter III indicates the evacuation analysis zones as defined by the Nuclear Regulatory Commission (NRC) and by the consultant in the study. Chapter IV presents population statistics based upon these zones. Chapter V explains evacuation action steps pertaining to the popu-lation groups studied for this phase of the study, and Chapter VI deals with the evacuation routes. Chapter VII presents estimates of evacuation times for various conditions studied. Also in Chapter VII, the results of l { this study are integrated with the previous study results and overall find-ings and recommendations are presented. In Chapter VII , the consultant I also investigated possibilities _ for both staged and partial evacuations and has recommended overall scenarios for operations planning to respond to various levels of urgency in an evacuation of the entire study area. l 3 4 k.
l II. AREA CHARACTERISTICS A. Topographic Features and Development The development pattern in the Five Cities area is strongly related to the topography. In the northern portion, in the vicinity of Pismo Beach, crbanization extends along a narrow shelf between the coastal mountain range and the Pacific Ocean. Canyons stretching inland contain lower density housing, mineral-resource industries, agriculture and ranch lands. South of Pismo Beach is a triangular portion of low-lying, flat land bounded by U.S. 101, the Nipomo Mesa, and the Pacific Ocean. Here are located Grover City, Oceano and the western half of Arroyo Grande, which together contain the majority of the population within the added study area. The urbanized area ends at Arroyo Grande Creek, south of which is the agricultural land of the Cienega Valley. Both Pis-mo Beach and Arroyo Grande contain densely developed areas extending short distances inland across into the valleys or canyon lands. Some new residential development is likely to occur east of U.S.101, but most future development is projected along the established Route 101 corridor. (See also Chapter IV.) B. Transportation Network The transportation network has been described in detail in the previous report. Additional significant highway facilities in the Five Cities are: e U.S. 101 continuing south to the county boundary as a four-lane freeway (with a short expressway segment south of Arroyo Grande).
- The frontage road which parallels Route 101 to the west to become Route 1 in Pismo Beach branches off in a coastal direction, south of Pismo Beach.
1 4
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- The secondary evacuation routes out of San Luis Obispo to the southeast, namely State Route 227 and Orcutt Road. These roads cross-connect with a number of canyon roads and feed back to the Route 101 at the Price Canyon Road interchange in Pismo Beach, Oak Park Boulevard interchange' on the Grover City / Arroyo Grande boundary, and at the E. Branch Street / Traffic Way inter-changes in Arroyo Grande.
- L'os Berros - Arroyo Grande Road which commences of f Valley Road in Arroyo Grande and, through various connections, forms a con-j tinuous secondary route out of the county.
In addition to the major routes are the local streets which connect into the main highway system. Those local routes which would be important for evacua-tion purposes are described in detail in Chapter VI. Figure II-1 shows the street classification of roadway facilities within the Five Cities area. 1 4 J 5
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Table III-1 DESCRIPTION OF EVACUATION ANALYSIS ZONES Analysis Zone Limits XVI Commence at intersection of Southern Pacific railroad (SPRR) tracks and Pismo State route 227
- State Route 227 southeast to Canada Verde Creek
- Imaginary line southwest through hills (crossing saddle of Ormonde Road to Pismo Beach city limit near U.S. 101, N. 4th Street interchange
- Pismo Beach city limits east, south, west to Pacific Ocean
- Pacific Ocean northwest to Spyglass Rd.
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- Imaginary line from Indian Knob to in-tersection of SPRR and route 227 XVII Commence at intersection of SPRR tracks f
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- Route 227 southeast to Arroyo Grande city limits
- Arroyo Grande city limits j - Southeast then southwest to U.S. 101
- U.S. 101 northwest to zone XVI
- - Zone XVI boundary northeast to State Route 227 XVIII Commence at U.S. 101 near N. 4th Street interchange Arroyo Grande
- U.S. 101 southeast to A royo Grande city limits
- Arroyo Grande city limits southwest to j
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- Arroyo Grande Creek west to Pacific Ocean
- Pacific Ocean north to Pismo Beach city limits l
- Zone XVI boundary east to U.S. 101 l
11
IV. POPULATION, INSTITUTIONS, AND VEHICLE TRIP GENERATION WITHIN THE EVACUATION AREA A. Residential Population and Employment Travel Patterns In order to estimate the number of vehicles which would be used in an evacuation, up-to-date population estimates were utilized. These were obtained by analyzing population and dwelling unit information provided by the county and state planning departments and by projecting short-range trends to update these data. The resulting population estimates for the three analysis zones were largely based upon dwelling unit information. Since, for conservative reasons, a zero percent vacancy rate was assumed, the population figures used here are higher than the official local estimates which incorporate a vacancy rate as high as ten percent due to factors such as the large number of vacation homes in the area. Estimates were up-dated to July 1980, and July 1985 - the latter as an indication of short-range growth. The distribution of population and dwelling units within the study area t l was based on established development patterns and facilitated by the l fact that a number of city boundaries coincided with those of the analysis j zones. Estimates of the population and of the dwelling units are shown by NRC zones in Table IV-1, and by evacuation analysis zones in Table IV-2. As of July 1980, the total estimated population in the added study area is expected to be about 31,800 persons in 13,300 dwelling units. Pro-l jections for 1985 show an increase of approximately 4,800 inhabitants and in 3,300 dwelling units. As can be seen from Table IV-1, the current (July 1980) estimated population within the entire study boundary (in-cluding both Phases I and II) is distributed by distance from the Diablo Canyon plant as follows: I l 12
l n Tahle IV-1 ESTIMATED WELLING UNITS AND POPULATION SY NRC ZONES l NRC Zones Number of Dwelling Units Population 7/80 7/85 7/80 7/85 E 10-151 / 38 46 75 56 F 10-15 5,477 6,763 12,058 13,828 t E 15-20 47 57 119 133 F _ -20 7,801 9,711 19,589 22,533 TOTAL 13,363 16,577 31,841 36,580 1/ Includes Phase II Study area quantities only; part of this zone was included in the Phase I Study in Table IV-1 under the combined NRC Zone CDE 10-15. 13
. . . ._ _ , . _ , , _ _ , - - _ , .__ . , ~ , . _ . - _ - - - . - - _ . , _
Tahle IV-2 ESTIMATED DWELLING UNITS AND POPULATION BY EVACUATION ZONES Number of Dwelling Units Population 1/ Evacuation Zones 7/80 7/85 7/80 7/85 XVI Pismo 3175 3878 6276 7119 XVII Arroyo Grande North 1878 2285 4774 5324 XVIII Arroyo Grande 8310 10,414 20,791 24,137 TOTAL 13,363 16,577 31,841 36,580 1/ Does not include group quarters; includes population indicates as dwelling unit population in census reports estimated with a 0% vacancy rate. 14 l l
Population Percent Within 2 miles of plant 5 very small Within 2-6 miles of plant 58 0.1% Within 6-10 miles of plant 17,582 18.4% Within 10-15 miles of plant 57,986 60.8% 3eyond 15 miles of plant 19,708 20.7% Total 95,339 100.0% In addition to the analysis of population and dwelling units, an estimate of the travel time distribuiten of workers who return to their home prior to evacuation from the Five Cities area was made. This estimate was based upon the trip-end distribution for all trips whether employ =ent based or not, as tabulated in the county regional transportation plan.1/ Excluding those who travel internally or to adjacent rural areas, this infor=ation indicated for the Five Cities area that trips were split evenly between the City of San Luis Obispo and to Santa Maria and other cities in Santa Barbara County to the south. B. Car Ownership and Vehicle Generation To estimate the number of vehicles that would be used in an evacuation by the residents of the study area, assumptions and procedures identical to those used in the first phase of analysis were used. Based upon these assumptions, an estimated 15,500 vehicles would be generated in an evauca-tion which indicates an average vehicle occupancy factor of 2.05 for residential-based evacuation trips. Table IV-3 indicates the number of cars generated by each' evacuation zone based upon the July,1980 population and dwelling unit information. Also included is an estimate of the amount of non-car-owning households within 1/ JHK Associates, " San Luis Obispo Regional Transportation Study Technical Report Phase II", November 1974, pg. 2-30. 15 t
Table IV-3 ESTIMATE OF AUTOMOBILES USED FOR EVACUATION Number of Number of Vehicles Non-Car-Evacuation Number of Used for Owning Zone Households Evacuation Households XVI 3175 3690 285 XVII 1878 2180 165 XVIII 8310 9645 730 TOTAL 13,363 15,515 1180 l l uz. l I 16 l l
1 I i each zone. As was discussed in the previous study, special actions would need to be taken to evacuate these transportation dependent households. In addition to trips made by the resident population, evacuation trips would be generated by "special generators" such as schools, hospitals, and by the beach users - both day users and overnight visitors. These special population groups are discussed in more detail in sections C and D. C. Institutions In the case of an evacuation, ins itutions would need to be handled on a case-by-case basis, taking into account the special needs such as transpor-tation requirements, demanded by each. The previous study outlined some of these needs and concerns. For reasons discussed in that report, in-stitutions would not necessarily generate evacuation traf fic of Cae same proportions nor time characteristics as would the residential dwelling units. On the other hand, there would be a critical need for specialized transportation services such as buses or ambulances to evacuate these generators. General and Convalescent Hospitals Within the added evacuation area there are currently five operating hos-pitals - one general hospital and four convalescent hospitals. Table fV-4 indicates the characteristics of each of these medical facilities, and in-dicates the number of passenger vehicles that would have to be added to the evacuation traffic. In addition, the location of each of these facilities is plotted in Figure IV-1.
, 17
Table IV-4 ESTIMATED VEHlCLE GENERATION OF
- GENERAL AND CONVALESCENT HOSPITALS Average Number Staff Vehicles Facilities Seds of Patients (Day Shift) Gene rate d17 General Hospital Arroyo Grande Com-munity Hospital 79 70 110 110 Convalescent Hospitals South County Convalescent Center 99 99 30 55 Patio Home Care 24 24 3 10 Oak Park Manor 24 24 4 11 The Alder House Guest Home 6 6 2 4 1/ Does not include the number of ambulance trips generated as these trips would not be characteristic of the general flow of traffic. These trips were derived by estimating the number of staff, outpatient and visitor vehicles that would be generated.
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Schools Within the study area there are 12 public schools and three private schools of varying size.1/ The largest is Arroyo Grande Union High School with about 2,000 students. The locations of these schools are indicated on Figure IV-2. Since the method of evacuation of the schools would depend heavily upon time of day and available transportation resources, it is difficult to predict the traffic flow which would result.
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latter procedure would provide for a fast and possibly more assured evacuation provided that sufficient school and other buses can be procured for the timely evacuation of schools. The number of vehicles involved in evacuating the schools would not significantly affect the evacuation times for the general public. On the other hand, because of the evacuation plan variabl- which are unresolved at this point, it is not possible to make an accurate assessment of the evacuation times for school children. However, a range of times can be indicated, based upon certain assumptions. The 1975 county-wide population breakdown by age when applied to the study area population yields the following estimate: A_ge Category Percent Estimated Quantity 0-4 Pre-School 7% 6700 5-9 K-3rd Grade 8% 7600 10-14 4th-8th Grade 9% 8600 15-19 High School 9% 8600 33% 24,800 Estimate. 5-19 yrs. l 1/ Includes public and private schools as listed in the 1979-1980 San Luis j Obispo County School Directory. l l 20
These individuals could be evacuated in a variety of ways. The children in the pre-school category would largely be with the parent (s) or else under some form of day-care which would insure that the children vere either returned to their parents' care or transported to a reception center. Of the remaining children enrolled in public or private schools, so=e current-ly walk to school, some are bused and some =ay drive. Although the pre-ferred plan from an administrator's point of viev =ay be to directly evacuate all the children to pre-determined reception points, a comparison to the number of available buses (about 120 buses countyvide, representing about 6,000 seats) indicates that this would not be feasible if each piece of equipment were li=ited to two total trips. (Two trips could be accom-plished, including mobilization, loading / unloading and driving times twice to the school and twice to the reception center, in approximately five to eight hours, which is generally the same as the overall evacuation timeframe for the evacuation of the entire study area.) Because of this, it would probably be necessary to allow, on a pre-arranged basis, for a certain percentage of parents to pick up the children at the school, especially for the kindergarden-3rd grade age group. It may also be possible for some high school students to be authorized to be signed out from school and form car-pools. In this =anner, the re- =aining number required to be bused would be within the li=it of the im-mediatly available equipment, using rwo trips. It should be noted, however, that the detailed method adopted vill involve some key evacuation policy decisions which will still need to be resolved. D. Recreation and Tourism The added study area contains recreational' facilities centered around Pismo Beach which draw significant numbers of non-resident visitors. Pismo Beach State Park is the single largest attraction vSich includes day use, camping, and off-highway vehicle (OHV) operation by permit within designated areas. Other attractions outside of the state beach include motels, recreational vehicle parks and some smaller, local beaches. 20A
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Different travel patterns are associated with these various generators. Motel occupancy is close to 100 percent during the summer months and re-mains at about 60 percent in the off season. By serving many users at a single spot over the course of a year, the recreational vehicle parks also have a high occupancy rate. In contrast to these facilities, the'use of Pismo State Beach is more subject to summer peaks, especially during longer holiday weekends when vehicles are driven onto the beach. Consequently, two analysis cases were established and analyzed: A non-peak condition in which all activities except the State Beach were taken at capacity. e PeakconditienatPismoStateBeachinaddigiontofullutiliza-tion of the other recreational facilities.1 The first case represents a situation where either the Beach State Park is not evacuated, while the other recreational areas are, or a case of moder- , ately high use and evacuation of all facilities including the Pismo Beach State Park. This case would be representative of a normal summer week-day or non-peak weekend. The second case represents a highly peaked situation such as might occur on a Memorial Day, Fourth-of-July, or Labor Day weekend. , Estimates of the total number of camping, motel and day-use visitors to the l coastal zone were prepared with the aid of the State Parks Department of-ficials at Pismo Beach and the City of Pismo Beach Planning Department. _ These estimates were based on the following assumptions: for minor ca= ping and beach areas, the number of vehicles was based upon the number of avail-l able campsites or parking spaces; for motels, the number of rooms used. For the Beach State Park, the usage was based upon peak visitation data directly. The resulting estimates are shown in Table IV-5. l 1/ During peak usage, recreational population at Pismo State Beach extends i into areas of the beach beyond the evacuation study boundary. (See Figure I-1) i However, evacuation frem the beach would take place through access points lo- ' l cated within the study boundary, and this traffic was included in Scenario C. l l 22 i
l Table IV-5 RECREATIONAL TRIPS Vehicles Activity Estimated Arroyo Grande Motel 105 RV Park 60 City of Pismo Beach Motel 920 RV Park 990 ( Beach (Shell Beach) 200 Pismo Beach State Park Beach (North of Arroyo Grande Creek) 100 Beach (South of Arroyo Grande Creek) 8600 Camping (North Beach Campground) 103 i Camping (Oceano Campground) 84 l l 23 l
E. Summary of Total Evacuation Table IV-6 indicates, by analysis zone, the estimated total evacuation traffic composed of residential-based vehicles, and those private vehicles - generated by special facilities, i.e. medical recreational facilities. As described above, Pismo State Beach is not included in this table, since
*raffic generated by this facility is treated in a separate analysis. (See Scenario "C", Chapter VI.) -
e e e e 6 24
Table IV-6
SUMMARY
OF ESTIMATED NUMBER OF VEHICLES GENERATED BY ANALYSIS ZONE Total Residential Vehicles Added by y Vehicles Zones Based Vehicles Special Generators- f Generated i XVI 3690 920 Motel 5,800 200 Beach 990 RV Park 2110 XVII 2180 20 Misc. 2,200 XVIII 9645 105 Motel 60 Camping /RV Park 10,000 190 Hospital /Conval-escent Hospital 355 15,515
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TOTAL 2485 18,000 1/ Excluding Pismo State Beach I l
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V. DEVELOPMENT OF EVACUATION CURVES In order to determine the number of vehicles generated for each interval of time within an evacuation, a set of probabalistic curves was daveloped. These curves indicate what percentage of the total population would be leaving their home in terms of elapsed time since the initial siren notifi-cation system had been sounded. A more complete discussion of the evacua-tion curves was contained in the Phase I report. However, for the Five Cities study area it was necessary to develop some additional evacuation
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curves in order to represent the evacuation behavior of beach and recrea-tional visitors. These r arves are shown in Figure V-1. For this study, two different beach population groups were considered, those who would have to walk to their vehicles upon evacuation notifica-tion and those who would be with their vehicles but dispersed on the beach. The second category was necessary due to the fact that Pismo State Beach is a state park where Off Highway Vehicle (OHV) operation is permitted. It was assumed in the analysis that the notification of the beach popula-tion would take place by having a mobile loudspeaker system either air-i borne or carried by a park patrol vehicle. The shape of the notification j l curve would be then a function of the distribution of population upon the beach and the speed at which the area could be traversed. Based upon analysis of these factors, it was concluded that a notification curve similar to that previously used for the Phase I study would also be ap-plicable to the beach-recreational uses. This notification curve was then multiplied by the " prepare to leave" curves, which were different l for the walkers and those driving on the beach. The " prepare to leave" curves reflect the functions of packing up belongings, gathering of groups, and actual egress time to the egress point, and were based upon the specific conditions observed at Pismo State Beach. Since during a peak holiday time the state beach has such a large proportion of the total coast visitation, separate curves were not developed for other beach l 26 l
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1 s i zones in the study area. After the evacuation charactaristica of the twa distinct populations on the beach were determined, the curves were
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weighted and combined to form a single evacuation curve for the beach visitors. The development of the beach. curves and of the working population
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evacuation curve are compared in Figure V-1. The main difference between the beach curves and the working population curve is due to the reduced number of sequential steps required for beach evacuation. As a consequence of this, the beach areas have the potential to be very quickly evacuated. As can be seen in Figure V-1, the maximum evacuation starting time for beach visitors would be 1:45 hours versus 3:15 hours for workers. On I the other hand, unless additional alternate exit points can be located and the appropriate traffic control provided, the beach exit capacity will control evacuation time. In this case, the possibility would exist that long queues of vehicles, attempting to exit the beach would fo rm. The resulting delay was confirmed in a special analysis, labeled
" beach scenario", in Chapter VII. +
w 28
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VI. EVACUATION ROUTES A. Roadway System In this chapter, the additional qualifications are addressed concerning the roadway system which are unique to the added study area. Details
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outlining the relationship of the evacuation routes to the statewide transportation network, reception center locations and roadway capacities, were described and evaluated in the pre rious Phase I study. Main Freeway / Expressway Links As shown in Figure VI-1, U.S.101 is the only freeway / expressway link within the added study area. This facility acts as a spine along which most of the development and population within the added study area are spread out. Route 101 is constructed to freeway standards throughout
- most of its length within the study area, and the short expressway segments of this route traverse rural areas where there would be no sig-
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nificant traffic interference. State Route 1 and the Los Barrom - Arroyo Grande Road comprise the only other major evacuation through-routes that provide additional capacity out of the area to the south. Although Routes 1 and U.S.101 enter the study area as a common freeway f acility (Route 1 is separately defined as Dolliver Street in Pismo Beach), there exists a continuous frontage road on the west side of the f reeway which provides additional roadway capacity, l It should be noted t:'at for certain analysis scenarios described below, some of the available capacity of both Route 101 and other potential evacuation routes would be absorbed by evacuatit traffic from San Luis Obispo. Not l all of the full roadway capacity would, therefore, be available for Five-I Cities traffic depending on the respective evacuation assumptions. Road Capacity Assumptions The particular vehicle capacites used for Route 1 varies depending upon the actual quality of the facility. Throughout the added study area the 29 l I
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route functions as a two-lane road. However, within Pismo Beach there are numerous intersections. Thus a maximum capacity of 1200 vehicles per hour was used. Through Grover City, access to Route 1 is restricted to a few intersections due to the presence of the Southern Pacific Railway tracks. Similarly, south of Oceano Route 1 abuts agricultural fields and has only inf requent intersections. For these segments, an outbound capacity of 1500 vehicles per hour was used assuming little opposing flow and turning move ments. l l A small but important amount of additional capacity is provided by the Los Berros - Arroyo Grande Road. The analysis of this route shows that evacuation traffic leaving the study area on Los Barros Road could be directed through Nipomo via arterial streets (e.g. Thompson Road) to cross into Santa Barbara County either on Bonita School Road or along State Route 166. Because of the number of intersections involved in either of these routings, a lower capacity was assumed for this evacuation route than for Route 1.1! Traffic from the North Through the Five Cities Area j In some evacuation scenarios, traffic from the San Luis Obispo area would be directed through the Five Cities area. Traffic would thus be entering the Five-Cities area along the U.S.101 and its Frontage Road, as well as l along State Route 227 and Orcutt Road approaching on U.S.101. Traffic would be expected to remain on the freeway, and Frontage Road traffic would logically be directed onto Route 1. For analysis purposes it was assumed that Orcutt Road traffic would continue south and west through northern Arroyo Grande via Lopez Drive, Huasna Road, and Branch Street. This traffic would then be distributed onto Route 101, Los Berros Road or Route l 1 depending on which of the evacuation routes leaving the study area had l available capacity. Since the Orcutt Road traffic would utilize the entire capacity of the above mentioned route, it would be most sensible to load the Route 227 traf fic onto Route 101 as early as possible in order to 1 1/ Although the bridge on Bonita School Road across the Santa Maria River I was washed out this past winter, there are plans to replace the structure. The ultimate choice of route would be based upon the availability of Bonita School Road and the reception center location as Route 166 would lead traffic away to the east. 31
distribute the two flows to dif ferent entrance ramps. The most direct - routing was found to be via Price Catyon Road, requiring the placement of barricades across Route 227 at Price Canyon Road to divert this traffi-toward Pismo Beach. Local Routes In addition to evacuation through-routes local evacuation routes were designated which would serve as access routes to the evacuation through-routes. In general, these routes connect the local street systems with the freeway interchange ramps. Within the added study area, these routes are highlighted in Figure 71-2. They are also listed in Table VI-1, along with suggested alternative routes should the primary routes be blocked - for any reason. The analysis indicated that, relative to the initial study area of Phase I, the Five Cities area exhibits a greater redundancy of access streets to the - major evacuation routes. At the same time, there are fewer potential hazards which could cause a closure of these routes in the added study are a. Shed Areas and Uncongested Travel Times Table VI-2 lists uncongested travel times between the population evneroid of each analysis zone and the southern study boundary via the shortest - routing. Since, in general, evacuation behavior and roadway congestion determine evacuation times rather than the uncongested travel time, these results do not represent actual evacuation times. They do, however, provide an indication of the relative accessibility of the various anlaysis zones . to the evacuation botsidary, and give a measure of local road versus freeway travel for each zone.
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Table VI-l LOCAL EVACUATION ROLTES BY ZONE Zone Pri:me Routes Alternate Routes
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XVI l Price Canyon Road Or:nonde Road Shell Beach Road Mattie Road Price Street various local streets XVII State Route 227 Print: Road Oak Park Boulevard Branch Mill Road - l Noyes Road Cherry Avenue Traffic Way Corbett Canyon Road Hausna Road various local streets XVIII Grand Avenue Farroll Avenue Oak Park 3oulevard Brisco Road North Yourth Street So. E1:n Street - So. Halcyon Road So. 13th Street Valley Road Atlantic City Avenue Fair Oaks Avenue No. 12th Street Frontage Road various local streets e 6
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T Table VI-2
. UNCONGESTED EVACUATION TRAVEL TIMES Local Street Access Freeway Route Total Distance Speed Time Distance Speed Time Evacuation - Zone (Miles) MPH (Min.) (Miles) MPH Odin.) Time (Min.)
XVI y 4.8 30 9.6 4.4 45 5.9 15.5
~
XVI 0.7 20 2.1 6.3 45 8.4 10.5 2 XVI 3N 1.0 20 3.0 4.4 45 5.9 8.9 XVI S 0.5 20 1.5 4.4 45 5.9 7.4 3 3.3 7.7 XVII 2.2 30 4.4 2.5 45 1 XVII 2 1.2 25 2.9 0.5 45 0.7 3.6 XVIII 1
. 1.5 25 3.6 3.3 45 4.4 8.0 XVIII 1
1.6 25 3.8 2.5 45 3.3 7.1 XVIII 2 1.0 25 2.4 1.1 45 1.5 3.9 XVIII 2 2.3 25 5.5 NA1 NA NA 5.5 XVIII 2.1 25 5.0 NAA/ NA NA 5.0 3 l l i l 1/ Via Los Berros Road 2/ Via Route 1 southboun/ 35
Through Traffic - As was stated in the Phase I Report, the diversion of regional through traffic around the designated evacuation area would be an important conside ration in an evacuation plan. Desirably, long-distance through traffic would be - diverted ahead prior to reaching the Five Cities area. Road blocks would need to be set up on Route 1,101 and 166 at or below the Santa Barbara County line , to prevent through traffic from entering the evacuation area. Adequate north-south highway facilities exist outside the study area to - facilitate such through-traffic diversion as explained in the Phase I Report. B. Potential Hazards and Alternate Routes The Safety Element of the General Plan of San Luis Obispo County which elaborates upon the various natural hazards that are present within the county was used as a basis for evaluating which conditions could affect the integrity of the evacuation roadway system. The Safety Element addresses - a number of hazard categories which are of concern, including wildland fire, flooding, dam inundation and earthquakes. The hazards which appear to be most likely to affect the evacuation routes in the Five Cities area include the following: - e Wildland fire is a frequent : occurrence in the mesa west of Nipomo. This hazard could disrupt local evacuation routes Route 1, and could reduce the overall evacuation capacity to a considerable extent. - e Arroyo Grande creek is generally expected to remain within its streambed. However, should extreme flooding occur, local and major evacuation through-routes, exclusive of U.S.101, could be affected.
~
e Beyond the study area, in the vicinity of Nipomo, Route 1 is posted with warning signs indicating that the road floods during heavy rainfall. The road is expected to remain passible. e Inundation from landsliding into Lopez Reservoir could cause flooding within Arroyo Grande Valley. This flooding is - expected to be slow to develop, however, due to the flatness of the valley floor. 36 -
- Severe earthquakes could substantially disrupt the infrastructure within the Five Cities area through building collapse, utility line failure, subsequent fire, and landsliding. From the point of view of evacuation, a major concern would be the integrity of the bridges and ground slopes along the U.S. 101.
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- 3 more general discussion of these problems was contained in the Phase I Report, including an analysis of bridge structure along the f reeway evacuation routes. From this analysis it was concluded that it would be unrealistic and impossible to attempt assigning a specific traffic delay , time to these various potential hazard conditions.
However, the study looked for the existence of available alternative routes for the major evacuation routes in the czas that natural hazards should block
. certain road segments. Further, it is reconnended that in the course of evacuation planning, these problems be addressed on an individual basis I
and contingencyplans be prepared accordingly. At such a time, the likely duration of road blockages and their effects on the overall evacuation time can be assessed. An exception to this would be rainfall during an evacuation. For that condition, a 20 percent increase in evacuation time was estimated in Phase 1 which would also apply to the Five Cities evacua-tion. Finally, with regard to earthquake conditions, Figure VI-3 indicates major known utility lines within the Five Cities area. Means of verifying, or if necessary, re-establishing evacuation routes where these lines cross ! evacuation routes should be part of the emergency planning eff ort. l l l { l l 37 i
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VII. EVACUATION TIME ESTIMATES This chapter contains the estimates of delays and evacuation times that might result from an emergency situation at the Diablo Canyon Nuclear Facility. In order to reflect several potentially'different evacuation
, circumstances, three different evacuation scenarios were analyzed. Also J
included is a summary of the findings and conclusions that can be drawn from this study. I A. Evacuation Scenarios Three different evacuation scenarios were tested to determine the likely times required to evacuate the population from the designated Five Cities area. In addition, potential delays due to traf fic congestion were established. The conditions were selected to complement the evacuation scenarios assumed in the Phase I Study so that evacuation times for the combined study area l can be determined. In addition, the evacuation scenarios allow, through careful inference, the preparation of time estimates for other possible evacuation schemes not explicitly analyzed in either report. The alternative scenarios can be briefly described as follows: i e Scenario A21/ - Simultaneous Evacuation of Five Cities area and San Luis Obispo area with partial access control of ( Route 1 North of San Luis Obispo (see also Phase I Study, l Chapte r VII-B) . e Scenario B11 - Route 101 South reserved for Five Cities evacuation traffic only; San Luis Obispo evacuated via Routes 1 and 101 North, l e Scenario C - Similar to Scenario B1 with peak holiday traffic { evacuated f rom Pismo State Beach. i 1/ The scenario designations are identical to those used in Phase I. 39 t
Estimated traffic volumes for the three scenarios are shown in Figures VII-2 through VII-4 while delay times and final evacuation times ("last car out times) are indicated in Figures VII-5 through VII-7. As in the previous report, results are indicated across certain "screenlines" . which represent reference lines for comparison purposes. Figure VII-l indicates the three screenline locations: Screenline 9 crossing U.S.101 and State Route 1 i:: mediately south of Pismo Beach, Screenline 10 crossing the same f acilities immediately southeast of Grover City, and Screenline 11 crossing U.S. 101, Route 1 and Los Berros Road at the study area boundary. The combined screenline vehicle capacities are indicated in Table VII-1. Whether the total evacuation traffic demand was distributed across the screen- . line in accordance with available capacity or whether different allocations were made depended upon the specific conditions expected to be encountered. In instaces where it was thought to be difficult to achieve a good balance between demand and capacities the screenlines were broken and results shown separately for component facilities. This was typically done at Screen 11ne 11. Scenario A2 - Evacuation with Partial Access Control of Route 1 North In this scenario, evacuation delays on Route 1 north of San Luis Obispo would be minimized by preventing San Luis Obispo evacuation traffic from utilizing Route 1 initially. (See also Chapter VII of the Phase I Study Repo r t . ) If the Five Cities area is included in this analysis, additional delays would be incurred by evacuees from the San Luis Obispo area when they pass through the extended study area since they would need to share the roadway capacities with the Five Cities evacuation traffic. Figure VII -2 indicates the roadway volumes resulting from the Scenario A2 evacuation. A total of about 18,000 vehicles evacuate from the north (San Luis obispo) through the Five Cities area, while an additional 18,000 vehicles would be generated by the Five Cities area itself. The impact upon delay and evacuation time due to this overlap of traffic flows is 40
Table VII - 1 CAPACITIES OF CRITICAL SCREENLINES 15-Minute Screenline Road (s) Capacity
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9 U.S. 101 900 Route 1 375 (north of screenline 300)
- 10 U.S. 101 900 Route 1 375 11 U.S. 101 900
- Route 1 375 Los Berros Road 300 l
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indicated in Figure VII-5, which shows that the last vehicle would clear the evacuation boundary via U.S.101 at about 7:30 hours after notification to evacuate. This represents about a 31/2 hour longer time than would be the case if the Five Cities area would not be evacuated. The maximum delay encountered on Route U.S.101 at the study boundary screen-line is estimated at 105 minutes as also shown in Figure VII-5. As can be seen from the rosults at Screenline 9 there are substantial delays as far north as Pismo Beach in this scenario. In fact, the delay there exceeds that at the study boundary because the single entrance ramp in downtown Pismo Beach was found to be a major bottleneck. It should be noted that the last vehicle out of the evacuation area via U.S.101 leaves at 7:30 as compared to 6:45 on Route 1. The reason for this imbalance is the fact that more traffic can be expected to take to Route 101 than to Route 1 since the former facility, built to freeway standards, is more attractive for longer-distance travel and is most likely perceived by the population as the better of the two facilities. At the same time, due to the much larger capacity of U.S. 101 compared to Route 1, very little time would be saved by diversion of freeway-bound t raffic to the state route. In reviewing the Scenario A2 for both phases combined, it is apparent that vehicles choosing to exit San Luis Obispo to the north would leave the evacuation area at 3:15 to 4 :00 hours af ter notification while those traveling to the south may not clear the boundary until 7:30. Thus there is an overall imbalance in this scheme and it is not a preferred manner in which to evacuate the entire study area. Regardless, it was felt that without substantial evacuation control around the perimeter of the City of San Luis Obispo, such a condition could occur under a potential non-staged emergency evacuation. i 49 l
Scenario B1 - Southern Routes Reserved for Five Cities Traffic - As explained in the previous study, this analysis case represents a condition where traffic from the north is directed to exit r.o the north, thus freeing up all southern access routes, Route 101, Highway 227, and Orcutt Road, for , Five Cities traffic. It should be noted f rom the volures shrwn in Figure VII-3 that almost 60% of the 18,000 evacuating vehicles wou?.d use U.S.101, while the remaining 40% would share Route 1, and Los Berr.ss Road. Figure VII-6 shows the corresponding delay times and ti:ne of the last car out fo r this scenario. Also shown is delay at all internal screenlines. The elimination of traffic f rom San Luis Obispo reduces the maximum evacuation time f rom 7:30 hours as calcualted in Scenario A2 to 4:15 hours, a savings of more than three hours. At the same time, the evacuation times at the Route 1 North (Morro Bay) and Route 101 North (San Luis Obispo) increase to about 5:00 and 6:00 hours respectively.1/
~
Even with the reduced overall time for the Five Cities area, there is delay warranting local traffic control within the Five Cities area as evidenced by the up to 45 minutes delay calculated for the Grover City screenline (Screenline 10.) In comparing the results for the southern evacuation zones to the results for the sanne scenario described in the previous study, it is apparent that an evacuation with controls applied as assumed here would be reasonably well-balanced across the entire study area. By inference, it is possible to assume that, with diversion of a small amount of traffic to the south, nearly equal evacuation times could result. Thus Scenario B1 would result in shorter overall evacuation times than Scenario A2. 1/ See Figure VII-8 of Phase I Study Report. 50 -
However, while the estimated maximum delay times at the southern evacuation boundary (Five Cities area)and northwestern evacuation boundary (Morro Bay) are on the order of 45 to 60 minutes, the traffic delays on Route 101 North could be expected to amount up to two hours. To reduce these delays, two optional actions should be considered:
- a. To time-delay the notification to evacuate for San Luis Obispo by about 2-3 hours and then to permit use also of Route 101 South for San Luis Obispo area traffic, or
- b. To not time delay the evacuation but to implement traffic
~
control measures which would permit Route 101 to be used as , a one-way outbound-only facility between San Luis Obispo i and about Santa Margarita. This measure would reduce the delay to about 75 minutes or less from the up to 120 minutes
- delays if only two lanes were available.
i l 51 1 t
Scenario C - Peak 3esch Evacuation Simaltaneousiv vith Fiw Cities - As was noted in Chapter 17, the estimated Five Cities traffic includes a substantial assunt of non-resident recreatimal ::af fic in addition to residen-tial traffic genera ica. In Scenario C, an additienal 5900 ahicles were assumed to be evacuated frc= Fismo State 3each in addition to the usual traf fic, as might occur en a peak holiday weekend. Because of the vehicle six of traf fic evacuating f ron the beach, which would include s4stantial numbers of recrea:ional whicles and vehicles with trailers the best - operational scheme would be to reserw Reute 1 and Los Berres Read for beach traffic while the residents of the Five Cities would be directed to U.S. 101. The ef fect upcc the evacuation tim is shown in Figure VII-7, which illustrates how the evacuation time for the U.S.101 increases by abcut :vo hours to 6:15 hours as compared to 4:15 hours in Scenario 31. The lcng delays for beach traffic as shown in Figure 7 I-7 are largely the result of relatively - poor access to the beach area, which is centrolled by the two beach reps. Because the beach ::affic would be assigned to the Highway 1 and Les 3erros Icad evacuatice routes, a miner change in :he traffic agnitude veuld sc: affect - the evacuaticui time for the Five Cities traf fic. If there were substantially fever beach vehicles however, some Five Cities ::af fic could be shif:ed away fron the freeway :o icprove the owrall time. On the other ha::d, sh::uld there be sore beach vehicles than estimated, they could be directed to U.S.101 - af ter the Five Cities traffic is gene. In order to fully use this capacity, though, the beach access problen vould need to be solved. As was the case for Scenario 31, no San Luis Cbispo traffic was assumed to - overlap wi-J the Five Cities evacuatice in Scenario C. It can be infer red fron this analysis that an additienal two hcurs would have to be added to the Scenario A2 times should a peak veekend beach evacuation be attempted .+.ile traffic free the San Luis Cbispo area vould be alleved :o evacuate :o the - south. 52 -
. R. Overall Evacuation Planning In conducting the evacuation time assessment study for the Diablo Canyon site, the consultant was able to identify a number of factors which were important in determining the overall time for the evacuation. Some of those f actors such as the population distribution of the study area could not be changed by adopting a different method of evacuation. However, if evacuation procedures different from those assumed in making the time estimate were to be used, there could be an impact upon the evacuation time.
The three dif ferent components of the total evacuation time identified in the scudy we re:
- 1) The preparation time prior to the commencement of the actual evacuation trip.1/
- 2) The actual movement time required to leave the area at a moderate speed, but not including added delay time due to traffic congestion.
- 3) Evacuation-caused traffic delay time, over and above that normally required for stopping at traffic signals and other traf fic control points.
In a typical evacuation scenario, half the population was estimated to have been evacuated by four hours. With reference to the above time components the four hour total would include 1.5 hours of preparation time, slightly less than 1.0 hour of movement time and about 1.5 hours of congestion delay. By contrast , the maximum evacuation time would involve 7.5 hours and would 1/ In this report section, preparation time includes the total preparation period, beginning with notification , and including, if appropriate , leaving place of work, packing, and securing the residence. 53
include 3.25 hours of preparation time,1.0 hour of movement time and 3.25 - hours in total traffic delay at various points. Based upon the above findings, it is apparent that the actual movement time is not a major portion of the total evacuation time. It should also be noted that an increase in evacuation traf fic speed is not necessarily an appropriate goal since the highest volumes of vehicles are moved at more moderate speeds and more importantly, higher speeds would lead to a higher incidence of accidents. - Of the remaining two components to the total evacuation time, a reduction of the preparaticn time would be possible if the concept of operation were changed. Although notification time is included in the preparation - time, noticeable improvement would not be gained through the use of a more sophisticated warning system -- the .tudy findings show over one half the population would be notified within 0.5 hour of the sounding of the sirens . If evacuation time were of essence, probably the single most . ef fective decision would be to instruct the public to directly evacuate regardless of their location at the time of notification. In other words, the public would immediately commence evacuating by means of the most readily available transportation. Although this approach is possible, there - are a number of problems which would need to be resolved prior to selecting this evacuation approach. First, additional road capacity must be found, otherwise the effect of a direct evacuation policy would be to exchange preparation time for road congestion delay time. Although direct evacuation . would enable some people to leave the area prior to the buildup of congestion, the study allocated the initial hour to the evacuation of those employees who work but do not reside in the evacuation zone, the clearing of the road system of through traffic, and the mobilization of official vehicles. . Because the road system would need to be used to meet these demands, it is probable that little additional road capacity would exist during the initial hour of evacuation. Another problem this evacuation process would raise would be the willingness of the public to abandon the area without gathe ring . their families, important personal belongings, and pets, and without securing
~
54
their homes. Presumably this would be a less important issue than personal safety, but such a directive may lead to a great deal of panic and hence make the evacuation unmanageable. Finally, the problems that would arise in obtaining additional exiting lanes need to be addressed. Shoulde r traffic and reverse-flow lanes on the major freeway facilities are an obvious me th od. In order for this to be done safely, there would be a significant added manpower requirement in the initial stages of the evacuation, beyond that required by a less complex plan. The remaining major time element in the evacuation process, the congestion delay time, could be reduced by increasing roadway capacity, or by staging departures. A capacity increase would involve the same level of effort, as discussed above, but if done in the absence of a substantial direct evacuation, there would be more time in whi'ch the traffic control personnel could install
- barricades, signs, diverters and establish field positions.
The other approach, staging, would not be expected to reduce the overall evacuation time. If properly conducted, this could reduce the problem of road congestion, and reduce the potential for panic by maintaining people in the relative safety of their homes prior the evacuation. l One of the questions regarding staging concerns compliance. To answer this, an analysis of the details of a staged evacuation may well indicate for this site the staging may not need to be followed absolutely in order to accomplish the primary goal of reducing congestion. In addition, since the prime egress routes are via freeway, the stationing of traffic control wardens at key ramp locations could allow for a high degree of control since the freeway tends to establish natural evacuation zones as it cuts through j the urban areas within the Diablo Canyon evacuation study area. A recent I major evacuation was successfully conducted using the staged technique in l response to the threat of poisonous gas release.1/ - 1/- NUS Corporation, " Status Report, Mississauga Evacuation Study," Rockville , l Maryland, March,1980, passim. 1 1 55
In terms of staging sequence , the analysis of the evacuation times has provided , a clear indication of the preferred manner in which to proceed provided the only concern is to minimize traffic congestion. The Baywood /Los Osos/Morro Bay area would evacuate to the north while the Avila Beach /Five Cities area would evacuate to the south. (These evacuations could take place , simultaneously or in any sequence since the evacuation routes are independent.) During this time U.S.101 heading north out of San Luis Obispo would be open as a " safety valve" to allow either voluntary or =andated evacuation f rom the central area. As soon as any of the coastal routes were to open , up (approximately 3.5 to 4.5 hours af ter the notification, assuming maximum population and normal roadway operation) traffic frem the high population zones in San Luis Obispo would be allowed onto the coastal routes provided there were no danger of conta=Ination f rom the plane. , In providing f or an evacuation the optimum emergency response plan would allow a dynamic response to the emergency situation. The plan could be based upon an evacuation of moderate expediency for the entire population , within the emergency planning zone. Other plan elements could then provide for partial evacuations should the danger be restricted to certain definable sub-zones. In addition, there could be dif ferent levels of traffic control relating to the various levels of urgency. For example, the basic evacuation , could be extended over time to allow for more organized departure with a minimum of control personnel required, or an extreme contigency could be drawn up in which additional exiting roadway capacity is gained at the risk of increased traffic accidents and with additional control nanpower , requirements and related costs. Finally, a response plan could allow certain groups to be notified for evacuation in advance of the general population, such as pregnant mothers and pre-school children (as was done at Three Mile Island) elderly people, and others with mobility limitations. , the consultant analyzed the evacuation times which would result with a minimum level of evacuation control. This was done in order to be conservative in estimating the evacuation times. In addition, the county emergency plan does not specify complex traf fic control measures nor does it address the manpower problems in evacuating a zone as large as that contemplated as a 56 .
result of the Three Mile Island experience. This does not mean certain expediting measures should not be instituted. As an example. additional lanes out of the Baywood /Los Osos area should be an evacuation planning goal. In addition, the capability for adding lanes on other major evacuation facilities should be investigated. As has been noted in the discussion of the evacuation scenarios for both phases, a staged evacuation is recommended to deal with the anticipated roadway congestion. Finally, as we explained earlier, direct evacuation was assumed in this analysis for certain population groups. One of the goals of developing an evacuation plan would be to determine the degree to which the direct evacuation method should be incorporated. ee i l l l 57 l I
C. Findings and Conclualona The following conclusions can be drawn from the evacuation time analysis for the Five Cities area: In the combined otudy area, which includes about 185 square e miles surrounding the Diablo Canyon Nuclear Power Plant, the current residential population of about 95,000 could be evacuated in five to eight hours with minor control measures (Evacuation Scenario A2). Added traffic control measures could reduce this time to four or six hours (Scenario B1). An estimated , 48,000 vehicles would be used in the evacuation, excluding buses and evacuation control traffic. e If only the Five Cities area were evacuated via the southern evacuation routes, tha estimated population of about 32,000 could be moved out in slightly over four hours. Some 18,000 , private vehicles would be Lnvolved. e A peak summer weekend influx of non-residents could add 8900 vehicles to the Five Cities evacuation if Pismo State Beach were heavily used. If these vehicles were evacuated simultaneously with the residential population, about two hours , would be added to the evacuation of southbound traffic. e As compared to the earlier Phase I study area, flooding hazards which could affect the evacuation routes are significantly less likely in the added study area. Although any earthquake-related destruction would be similar to that of the Phase 1 ' study area, there are in general more alternative routes available for the Five Cities area. e If the reduction of overall evacuation time were considered to be important, the first requirement would be to gain additional capacity through the incorporation of reverse-flow lanes or other traf fic operating procedures. In order to use these operating
~
procedures, a large amount of manpower would have to be quickly mobilized prior to any evacuation to obtain the added capacity. The direct and immediate evacuation of large numbers of the population woisld also reduce the overall evacuation time, provided that suf ficient capacity were first available. e If, on the other hand, the goal of a detailed evacuation plan were to reduce congestion delay to evacuation and to control panic, then it would be desirable to either increase capacity as discussed above or to arrange for staging of the evacuation. In a staged evacuation, overall evacuation time would not be reduced significantly but people would remain in the relative ' security of their homes prior to evacuation. In addition , staging would be a relatively simple manner to reduce roadway delay resulting f rom lack of capacity. 58
e If the evacuation were to be staged, the best evacuation strategy would be to evacuate first the coastal areas which are the
~ most likely to be affected due to the prevailing wind patterns.
In this case, traffic from the Los Osos/ Baywood /Morro Bay area would evacuate along the northern routes (mainly Route 1) while vehicles from the Avila Beach /Five Cities area would travel out to the south via Routes 101 and 1. During this initial evacuation time, U.S. 101 north of San Luis Obispo would be open to allow for some evacuation from that area. (In the event of urgency, the capacity could be nearly doubled by using both sides of the roadway.) At approximately four hours af ter the initial notification, the remaining
- evacuees from San Luis Obispo could be directed to the coastal evacuation routes, as they would become available, provided 1
, that there were no danger from a drifting plume.
e It is likely that the best emergency respmse plan will call for evacuations only as large in scope and as urgent in time as are required to respond to a particular eastgency problem. In those emergency cases when the evacuation would
~
need to be conducted in less than about eight hours, it would - be essentiel to incorporate in the plan some expediting measures such as closure of roads, opening of additional lanes, staging of certain zones, and an immediate and direct evacuation of certain population groups to the extent that the local resources will allow. 59
W APPENDIX A EVACUATION TIMES FOR SUB-AREAS L'ITHIN THE EVACUATION BOUNDARY l l l 1 l l S
4 i 1 A. GENERAL " t Purpose The evacuation scenarios analyzed in the Phase I and II reports were aimed at estimating the evacuation time of the entire zone within the evacuation
- boundary. The general extent of the the evacuation boundary for analysis purposes was established by PG&E at the initiation of the project, while the task of refining the boundary based upon practical planning considera-tions was left to the consultant. PG&E elected to analyze a plume exposure emergency planning zone (EPZ) in excess of the 10-mile limit suggested by NRC/ FEMA because urbanized zones were situated in three different direc-tions at, or immediately beyond, the'10-mile limit. Because of this, it was felt that any protective action such as evacusticu which may be required 1 as far as the 10-mile limit could not exactly be restricted to that distance.
On the other hand, NRC/ FEMA has requested in Appendix 4 of NUREG 0654/ FEMA Rep 1 that evacuation times for certain sub-zones of the plume exposure EPZ be determined. It is the purpose of this appendix to indicate evacuation , times of various combinations of sub-area based upon the previous work.
- Introduction i
l In the NRC/ FEMA request for evacuatio.1 time estimates the following sub-areas were suggested for the plume exposure EPZ: l Distance Area 2 miles two 180* sectors 5 miles four 90* sectors , about 10 miles four 90* sectors i i 1 l
. , , - ~_ - . -. . . . . , _ , - . --_y _.,,..-- .,, , . - _ , , - , . . - - , , - . . _ , -.
! t These criteria do not suit the site-specific conditions for Diablo Canyon for the following reasons: e Of the area within a 20-mile radius of the plant site, a sector , of more than 180-degrees contains the open ocean. , e The population within five to six miles of the pian is so low that an evacuation would be relatively earst to accomplish. e The existing low-population zone for Diablo Car. von is set at ' six miles, hence the intermediate distance coula be more appro- ~ , priately specified at that limit rather than five miles. l e The population groupings at and immediately beyond the 10-mile
! linit can be separ3ted into distinct sectors, but thiv are tiot disposed in 90-degree quadrants as noted by NRC/ FEMA.
i For these reasons, all of the various combinations of evacuation zones ! can be reduced to a few logical alternative areas. In this appendix these
- alternative e"acuation renes and corresponding evacuation times are presented.
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- 8. QUALIFYING REMARKS Sectoral Division The disposition of the urban zones surrounding the site is such that popula-tion concentrations within a 20-mile radius of the plant occur in three separate directions within the landward 180-degrees surrounding the plant.
> The three sectors are divided by imaginary lines at compass bearings of 35-degrees and 102.5-degrees, as shown in Figure I-1 of the Phase II report.
The three sectors include the following urban areas!
; Ceneral Sector Direction Urbanized Areas North - Los Osos/ Baywood
- Morro Bay Eas tnortheast - San Luis Obispo Southeast - Avila Beach
! - Five Cities Comparison of these sectoral lines with the study evacuation zones illustrated in Figure III-3 of the Phase I report and in Figure III-2 of the Phase It report shows that notification and evacuation of zones divided by these sectoral lines may be readily accomplished. Conversely, an attempt to further sub-divide into smaller angular sectors would be difficult to accomplish and j is probably unwarranted if the variability of the wind is taken into account.
I This is not to say that subdivision of evacuation zones to allow for more
~
orderly evacuation would not be possible; however, further division along sectoral lines is not very feasible from the point of view of notification to the public. ! Uncongested Evacuation Time In cases where a small number of vehicles would be generated, the evacuation l time would not be affected by the roadway rapacity. This condition was found
' in a number of sub-area evacuation alternatives discussed in Section C, below and the basis for estimating the evacuation time is as follows:
3 r Y
If the demand upon the road network does not exceed the capacity for a sig-nificant portion of the total evacuation time, then the total time will be the total movement preparation time and the uncongested evacuation travel time. The total movement preparation time is measured starting with the , initiation of notification and ending when the last population member commences the evacuation trip. This is the same as the evacuation curve as developed and explained in Chapter V of the Phase I report. These times were de-termined for the Diablo site to be from one hour,15-minutes to three hours. _ That is , the first evacuee would leave home at approximately one hour and fifteen minutes after the sounding of the siren system, while the last evacuees would commence the evacuation trip three hours after initial alerting. Since the uncongested travel times ranged from less than five to approximately - 30 minutes, an uncongested evacuation would have a 1:20 hour to 3:30 hour time frame. (That is, evacuees would pass the 12- to 18-mile evacuation boundary beginning one hour, twenty minutes af ter initiation of notification anc ending at three and one-half hours after the start of notification.) - e e
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C. EVACUATION ALTERNATIVES, 10-MILES OR LESS Two-Mile, Omnidirectional Evacuation As indicated by Table IV-1 of the Phase I report, there are about three residences within the two-mile radius of the plant. Clearly they could be evacuated within the time frame of the "uncongested evacuation" noted above. For this small-sized zone, the time frame to clear the two-mile radius vould be from one to three hours depending upon the location of the affected people at the time of notification and the steps required to pre-pare to evacuate. Six-Mile Evacuation Since all previous planning for Diablo Canyon has been based upon a six-mile Low Population Zone (LPZ), the discussion will address the concept of a six-mile evacuation here rather than the five-mile radius suggested in NUREG 0654. A six-mile evacuation would involve residential and recrea-tional population within the north and eastnortheast sectors previously dis-cussed.1/ Even if both sectors vera evacuated with the two-mile zone, there would be no congestion to delay the evacuation since the numbers are relatively small. (Approximately 24 dwelling units as noted in Table IV-1 of the Phase I report would be evacuated, primarily from the most remote parts of See Canyon, Prefumo Canyon and Clark Valley Roads as well as visitors and staff - at Montana de Oro State Park.) Thus, a six-mile evacuation, even if conducted in all directions, could be accomplished within 3 hours. Ten-Mile Evacuation j As noted in the Phase I report, it is not possible to clearly define a 10-l mile limit in terms of.useful man-made and natural boundaries. The major population center affected is the City of San Luis Obispo, where the 10-mile limit crosses the town boundary west of the freeway. A similar condition of smaller scale exists for Morro Bay, where a small r._mber of streets at 1/ In the sector south of the plant, there may be a very limited number of farm workers to be evacuated from a few parcels of land adjoining the l plant access road. ' l 5 i
1 the south end of the city are technically within the 10-mile limit. On the other hand, by reducing the boundary slightly, an approximate 10-mile evacuation could be accomplished by evacuating Avila Beach, Baywood /Los Osos, and the rural areas west of San Luis Obispo. Based upon the popula- - tion involved, even if all sectors were evacuated simultaneously, the evacua-tion would be uncongested except at Baywood /Los Osos, where times could reach four hours if no provisions were made to obtain an additional travel lane north up to Morro Bay. 4 P 1 i l l e 6 > l
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D. EVACUATION ALTERNATIVES BEYOND TEN MILES General Evacuation times for zones extending beyond 10 miles would be determincd by which of the three sectors (as described in section B) were included. All times developed for evacuations extending to the 12- to 18- mile evacua-tion boundary presumed simultaneous evacuation of all areas inside of the limit, for the sector (s) included. In addition, due to the small number of people within a six-mile radius, the times developed would allow for evacua-tion of all sectors inside of six miles. An important point to be made regarding these comparatively large-scale ac-tions is that the evacuation of the northern sector is independent from the evacuation of the southeastern sector; i.e., the evacuation time for Baywood / Los Osos and Morro Bay is not changed if a simultaneous evacuation for Avila 1 Beach and the Five Cities is being carried out.-/ On the other hand, the evacuation of the eastnortheastern. sector containing the City of San Luis Obispo would af fect a concurrent evacuation of either or both of these other sectors. Northern Sector (NRC Zones A, B) This evacuation is illustrated by inference in the Phase I study as scenario A2, where the resulting evacuation time was determined to be approximately four hours. (See Figure VII-7 of the Phase I report.) The fact that in the A2 study scenario, San Luis Obispo was considered to be simultaneously evacuating does not change the resulting time significantly, since the analysis ! assumed a roadblock on Route 1 for nearly the entire evacuation time frame. l However, if a contra-flow lane out of Baywood /Los Osos was temporarily added, the time could drop to about three hours and 30 minutes. 1,/ This statement is based upon the number of vehicles generated as compared to the road capacity and is not meant to address the issue of evacuation
- control resources, which were not analyzed.
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Eastnortheastern Sector (NRC Zones C, D, E) This sector contains the major traffic generators of the City of San Luis Obispo and the California Polytechnic State University, (Cal Poly), and - is the most populous of the three sectors. However, most of the population, including nearly all of the City of San Luis Obispo and Cal Poly are con-centrated within the central NRC sector D (ENE), in which the annual wind propability is 0.9% (see Figure II-2, Phase I report) . Thus, it is highly unlikely that a major evacuationwould be extended in this direction beyond l 10-miles with no prior evacuation of the more probable downwind sectors. Hence, the most applicable ti=es for this sector are those that include evacuation cf other sectors simulatneously, and the Phase I and Phase II reports were written accordingly. If, on the other hand, evacuation of the adjacent sectors had already been initiated, then the evacuation of the major sector to the east would depend upon the number of routes available. Scenario A2, as analyzed in the Phase I report, shows a time of 3:00 hours to 3:15 hours for evacuating this sector if all routes except Route 1 are available. Since this is close to the uncongested evacuation time, the full use of Route 1 would not reduce this minimum time significantly. Also in that report, Scenario 31 shows a 4:45 hours evacuation time at the San Luis Obispo city limit if 55 percent of the traffic were restricted to U.S. 101 north out of town and the remaining 45 percent used Route 1 to the north. (At Morro Bay, the traffic would clear at 5:15 hours if no evacuation from Baywood or Morro Bay were taking place simultaneously.) If i only U.S. 101 to the north or south were available, times would extend to approximately eight hours, assuming no capacity - increasing measures were attempted such as adding reverse-direction lanes. l Southeastern Sector (NRC Zone F, G) The evacuation of this sector is analogous to the Scenario B1 (Five Cities with full use of U.S.101) as analy:ed and presented in the Phase 11 report. In this case, the time was determined to be four hours. Although the evacuation of Avila Beach is not shown in the Phase II report under Scenario B1, it I is clear that Avila Beach evacuees could be directed north along Routa 101 ( 8 h
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with no change in overall evacuation time. If it were necessary to send Avila Beach traffic south with Five Cities traffic, the approximately 500 added vehicles would add a maximum of 15 minutes to the overall evacuation time. North and Eastnortheastern Sectors (NRC Zones R, A, B, C, D, E) The analysis for this case is identical to that presented in the Phase I report, and the evacuation times presented in that report for the various conditions that apply. Eastnortheastern and Southeastern Sectors (NRC Zones C, D, E, F, G) This combination of sectors would produce an evacuation that would be very similar to that analyzed as Scenario Bl. with the exception that added capacity would be available on Route 1 to relieve congestion in San Luis Obispo due to the lack of traffic from Northern sector. Consequently, the evacuation times would be from approximately four hours in the south to five hours in the north. North and Southeastern Sectors Since these sectors are independent from each other as described above, the estimated evacuation times would be as described for each sector alone. All Sectors l The analysis for this case is identical to that presented in the Phase 11 report for the combined study area, and the evacuation times presented in j that report for the various conditions that apply, i I t I 9 l
Ti t I AUTHORS AhD PRINCIPAL PARTICIPANTS IN THIS PROJECT - I m Alan M. Voorhees & Associates: Juergen A. Fehr Project Manager - Brent Ogden, Assistant Project Manager
- Richard Garland. Transportation Planner Leah Segawa, Transportation Planner i
Janice Eklund, Graphics 4 Lisa Morbidelli, Graphics Tonia Todd. Editing / Production - Denise Blair, Editing / Production i 1 L f o
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