ML19256B832
| ML19256B832 | |
| Person / Time | |
|---|---|
| Site: | Skagit |
| Issue date: | 08/14/1979 |
| From: | Hulman H, Hulman L, Stull E Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19256B830 | List: |
| References | |
| NUDOCS 7909200124 | |
| Download: ML19256B832 (8) | |
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UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD In the Matter of,
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PUGET SOUND POWER & LIGHT COMPANY,
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Docket Nos. STN 50-522 e
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STN 50-523 (Skagit Nuclear Power Project, Units 1 and 2)
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NRC STAFF SUPPLEMENTAL TESTIMONY ON FLOODPLAIN MANAGEMENT BY L. G. HULMAN AND E. A. STULL A.
Introduction Executive Order'11988, Flcodplain Management, was issued in May 1977 (42 FR 2E921) to assure that Feder31 agencies were following procedures "... to avoid to the extent possible the long term and short term adverse impacts assoc'iated with the occupancy and modifications of floodplains and to avoid direct and indirect suppori of floodplain development wherever there is a practicable alternative..." In addition, the. Guidelines for.Imple-menting Executive Order 11988 were adoptet by the Water Resources Council on January 25, 1978 and published on February 10, 1978 (43 FR 6030).
Execu-tive Order 11988 requres that Federal agencies attempt to reduce the risk of flood losses and to minimize the effects of floods by avoiding, where practicable, development in floodplains. Under the Order, Federal agencies with responsi-bilities for conducting Federal activities and programs affecting land use are required to evaluate the potential effects of any action they may take in a floodplain.
If an actior[ impacts the base floodplain (100 year flood), the Order further requires agencies to minimize potential harm to people and property, and to restore natural and beneficial floodplain values.
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Identification of Structures in Floodplain Plans for the Skagit Nuclear Power Project specify three facilities which will be located either, permanently or temporarily in the floodplain of the Skagit River. The Ranney Collectors (RM 39) will be located in the floodplain about 130 to 150 feet from the normal water's edge. The plant's discharge structure will be located in the river channel and will always be submerged, and finally, the Skagit River bank.
In a temporary barge slip will be constructed s a addition-several small creeks will be crossed by the make-up-water and discnarge water pipelines, transmission lines, and improved or new access roads; while a section of the upper portion of Tank Creek will be rerouted
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around the proposed site. Construction and/or operation of these parts of the Skagit project are expected to produce some impacts on natural and beneficial floodplain values. These values are associated with living resources (fish and wildlife, riparian habitat, and wetlands), cultural resources (historic or archeological sites and recreation areas), and cultivated resources (farmlands and timberlands). Staff arsessments of impacts on resources to which natural and beneficial floodplain salues are ascribed have already been addressed in the hearing record, in the FES, and in the FES Supplement. The Staff assessment of specific hydrological impacts is presented in this testimony.
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Sumary of Impacts to Natural Floodplain Values Placement of the Ranney Collectors is expected to produce short-term aesthetic impacts to the recreational resources at RM 39, and a smal11 amount of second growth scrub and alder thickets will be preempted by caissons and enclosure fences. Alternatives to the Ranney Collectors at RM 39 include alternative designs and alternative locations which the applicant has addressed in the 122:
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" ER and the Staff has addressed in the FES and the FES Supplement. The Staff expects the impacts from other intake designs such as sidewall collectors or midchannel intakes would have greater impacts on fishery and recreational resources of the Skagit River than the proposed Ranney Collectors. The Staff concludes that the presint location of the Ranney Collectors minimizes impacts i
to floodplain values because the location avoids makeup water lines in the Skagit floodplain and the intakes disturb neither wetlands nor agricultural areas.
In addition, changes in the proposed design of the Ranney Collectors since publication of the FL5 are expected to minimize noise and visual impacts on recreational resources of the Skagit River at the intake location.
Tne buried makeup and discharge water lines, access road crossings, and trans-mission lines are expected to cross several creeks. These crossings are outside the floodplain of the Skagit River and largely involve small streams of -teep gradient without significant floodplain features. Some sedir.ents from con-struction along the streams might reach the Skagit River ficodplain, but the Staff expects such sedimentation to be insignificant compared to siltation from agricultural lands. Staff expects sedimentation impacts from construction activities on Skagit River tributary creeks to be negligible on Skagit River floudplain aquatic communities.
Construction of the barge slip would disturb approxir.ately 250 feet of shoreline which is covered with grasses, shrubs, and alders This plant community would rapidly become reestablished if the slip were temporary. Permanent use of the barge slip could increase recreational use of the Skagit River.
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-4 Based on examination of previous Staff testimony and reexamination of the Skagit Valley, the Staff concludes that the previous record has adequately addressed impacts to floodplain values associated with living, cultural, and cultivated resources. These impacts are expected to be minor and temporary.
'. Hydrologic Impacts D
The only potentially important hydrologic != pacts of these structures in the floodplair old be their effects on the flow carrying capacity of the over-banks, which could modify the effects of a flood in terms of water level and flow velocity. A transient flood wave travelling down river is attenuated by bar.k storage. The larger the volume of the floodplain overbank areas, the
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greater the flood is attenuated.
In the case of the Skagit plant, the bar '-
storage vclume displaced by the floodplain structures js minute in comparison i
with the total storage volume of the floodplain. We judge the effect to be inconsequential. A more important effect of the structures is that they will reduce the cross-sectional area of the floodplain (encroachment). Significant encroachment could cause a higher water level and lower velucities upstream of the obstruction, and a lowr.r level downstream with attendant higher velocities.
The greater the encroachmett the further upstream and downstream would be the effect. The Staff analysed the effects of encroachment on the floodplain from the Ranney Collector buildings and the Barge Slip unloading facility.
The four Ranney Collector buildings each present a cross sectional width of about 40 feet to the river, which during the 100 year flood is no less than 8600 feet wide at the Ranney Collectors location. We consers.tvely assumed
'that the resistance to flow of the overbanks is the same as that of the 122" 296 h
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" normal river channel, and therefore, an increase of the base flood depth of only 0.08 feet was calculated. The correrponding change in the flow velocity would be negligible. Actually, the resistance to flow of the heavily treed overbanks is much greater than that of the natural channel, so the actual increase in flood elevation should be smaller than this figure.
The excavated material from construction of the barge slip and unloading facilit, sill be placed on the shore of the river and will be stored there for eventual replacement. The Staff estimates that the mound will be about 8.5 feet high and 140 feet long, but will present an encroachment of only 110 lineal feet into the floodplain during the 100 year flood. The 100 year floodplain at the barge slip is no less than 4800 feet wide. We estimate that the increase in river flood elevation upstream will be less than 0.3 feet due to the obstruction. Again, the corresponding change in velocity would be negligible. This analysis also assumed equal resistance to flow in both the natural river channel and overbank and is, therefore, conservative.
In addition, flood flows could completely inur.Jate the earthen mound.
Based upon the above, we conclude that the hydrologic impacts of these structures built in the floodplain is minimal.
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Conclusion Although the major structures associated with the Skagit flucl' ear Power Project will be located outside of the Skagit River floodplain, the specific structures pre-viously ;dentified will be located within the floodplain. Since hqse tures
6-need to be located on or near the Skagit River, the Staff has concluded that there is no practicable alternative for these structures which would avoid the floodplain.
e Accordingly, based on our evaluation set forth above and the assessments set forth in the FES, FES Supplement, and in previouc NRC Staff testimony, we conclude that the impacts of these structures to natural floodplain values will be minimal and that they (1) will not contribute to the hazard and the risk of flood loss; (2) they will not increase the impact of floods on human safety, health and welfare; and (3) will not degrade the natural and bene-ficial floodplain values.
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Lewis G. Hulman, Chief Hydrology-Meteorology Branch
.1-Division of Site Safety and Environmental Analysis Office of Nuclea*r Reactor Regulation Professional Qualifications I am Cnief of the Hydrology-Meteorology Branch, Division of Site Safety and Environmental Analysis, Office of Nuclear Reactor Regulation.
% fomal education consists of study in Civil Engineering at the University of Iowa where I received a BSCE in 1958, and an MS in Mechanics and Hydraulics in 1967. The graduate study was under total sponsorship of the Corps of Engineers. In addition, I have taken post-graduate courses in structural engineering at the University of Nebraska, coastal engineering at MIT, hydraulics and sedimentation at Colorado State University, advanced mathematics through the University of California and numerous management, technical and computer utilization courses sponsored by the government. I have had courses in hydrology, wa,ter resources, dam design, fluid mechanics, engineering construction, soil mechanics, water supply, hydropower development, sedimentation, geology, meteorology, advanced mathematics, groundwater, coastal engineering, and hydrometeorology.
% employment with NRC'(formerly AEC) dates from February 1971 primarily in the area of hydrologic engineering with both the Office of Nuclear Reactor Regulation and with Reactor Standards, and for consultation on siting of materials utilization facilities. Assignments are made on both safety and ert ironmental matters. % responsibilities in the licensing review of nuclear fe:ilities is are the areas of flood vulnerability, water supply, surface ant. groundwater acceptability of effluents, severe meteorologic events and diffusion analyses.
In addition, I participate in the development of the technical bases for safety guides and standards, and research identification and analysis in these areas of interest.
I am the agency representative on the Hydrology Comittee of the U. S. Water Resources Council, the agency alternate representative on the U. S. Geological Survey Federal Advisory Comittee on Water Data and' have' served on several agency internal task forces.
I have either reviewed or supervised the review of hydrologic engineering aspects of all nuclear power p1 ant and many fuels and materials facilities applications since joining the Comission in 1971. Since January 1976 I have also supervised meteorology reviews.
From 1968 to 1971, I was a Hydraulic Engineer with the Corps of Engineers' Hydrologic Engineering Center in Davis, California.
I worked on special hydrologic engineering projects with most Corps' offices, participated as an instructor in training courses, and conducted research.
Special projects work included water supply systens analysis for the Panama Canal, planning
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g Lewis G. Hulman Professional Qualifications
.,,..' i' 1 hydrologic engineering studies for water resource development near Fairbanks, Alaska, regional water supply and flood control studies for the northeastern U.
S., design hydropower and water supply studies for a dam in the northeast, and flood control studies in Mississippi.
Fr.om 1963 to 1968, I was a Supervisory Hydraulic Engineer with the Philadelphia District, Corps of Engineers. As Assistant Chief of the Hydraulics Branch, I was responsible for hydrologic and hydraulic desien of multi-purpose dams, navigation projects, coastal engineering development and special studi.es on hydraulic modeling of dams, inlets, water supply, and shoaling, salt water intra:fon, and the hydraulic effects of dredging.
I acted as advisor to the District Engineer, Philadelphia, on drought problems in the 1960's and represented him in technical meetings of the Delaware River Basin Comission - chaired interagency committee which evaluated the effects of the drought.
- From 1958 to 1963, I was a Hydraulic Engineer with the Omaha District of the-Corps of Engineers.
I was responsible for the hydraulic design of flood control channels, hydraulic design of structures for large dams and several flood control projects.
I also received training in hydrologic engineering, structural engineering, sedimentation, river training studies and design, and water resource project formulation I have published in journals of the Merican Society of Civil Engineers, the American Water Works Association, the Journal of Marine Geodesy, the National Society of Professional Engineers, the Merican Geophysical Union, and in internal technical papers and seimnar proceedings of the Corps of Engineers.
I am a registered Professional Engineer in the States of Nebraska and California.
I am a member of the Anerican Society of Civil Engineers, the Merfran Water'Ruscorces Associatior, the American Meteorological Society, and the Anerican Geophysical Union.
I am the NRC staff representative on the Hydrology Comittee of the. Water Resources Council, and the Federal Advisory Comittee,an Water Data.
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