HBL-86-023, Requests Approval for Offsite Disposal of Listed Very Low Radwastes as Produced,W/O Individual Authorization.Util Will Sample Wastes & Monitor Radioactivity Per NRC Approved 831027 & 840407 Transmittals.Fee Paid

Requests Approval for Offsite Disposal of Listed Very Low Radwastes as Produced,W/O Individual Authorization.Util Will Sample Wastes & Monitor Radioactivity Per NRC Approved 831027 & 840407 Transmittals.Fee Paid

ML20199E884
Person / Time
Site:	Humboldt Bay
Issue date:	06/17/1986
From:	Shiffer J PACIFIC GAS & ELECTRIC CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
HBL-86-023, HBL-86-23, NUDOCS 8606240136
Download: ML20199E884 (18)

Text

v PACIFIC GAS AND E LE C T RIC C O M PANY h @?b'/5i i

{ 77 BEALE STREET

• SAN FR ANCISCO, C ALIFOR NI A 94106 . (415)781-4211

• TWX 910-372 6587 d AMES D. SHIFFE R wct paissotwY ucuo . . " "'**

June 17, 1986 PGandE Letter No.: HBL-86-023 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Re: Docket No. 50-133, OL-DPR-7 Humboldt Bay Power Plant, Unit 3 Very Low-Level Radioactive Haste Disposal

Dear Mr. Denton:

On October 27, 1983, Pacific Gas and Electric Company (PGandE) requested approval to dispose of low-level radioactive contaminated waste at a Class I disposal site for hazardous waste. The waste included oil and sludge from an onsite oily water separator (OHS) and is classified as hazardous under Federal Resource Conservation and Recovery Act and State of California regulations.

The NRC Staff reviewed PGandE's request and concluded on May 7, 1984, that the proposed transfer of the waste to the IT Corporation's Benicia, California disposal site was acceptable. The waste was transferred in September 1984. '

On April 25, 1985, PGandE requested a similar approval for disposal of low-level radioactive contaminated wastewater treatment pond sludge and fossil fueled boiler firebox waste. This approval was granted by the NRC on ,

September 3, 1985. Shipment of the waste is pending at this time.

Regulations applying to the operation of the wastewater treatment ponds and the OHS system require that accumulated waste material be removed and that the ponds be inspected annually. In anticipation of cleaning out the OHS system, 1 a sample of the sludge was taken to determine if any residual contamination i was present. Gamma spectroscopy analysis of the sample indicated that the present level of radioactive contamination was approximately 2 pCi/gm of Cs-137 and Co-60, respectively, the principal isotopes present. This is less than the level of radioactive contamination in the sludge transferred in September 1984. The source of the present radioactive contamination appears I to be residual material remaining in the OHS following sludge removal and also I residual material present in the drain systems supplying the OHS. The OHS l effluent flows to the wastewater treatment ponds, thereby providing a possible  !

route for radioactive contamination to reach the ponds. The detection of very low levels of radioactive contamination in the OHS and wastewater treatment pond systems in the future is expected due to the very low-level detection limits of the present plant instrumentation. \

pw ADOCK~05000133 ~0-as 41 kC.C., c c4fcC4 g450.oo

\

Mr. H. R. Denton i PGandE Letter HBL-86-023 '

June 17, 1986 Page 2 PGandE expects to generate the following quantities of wastes that may require NRC approval prior to disposal under 10 CFR 20.302(a): l HASTE TYPE QUANTITY Hastewater Treatment Pond Sludge 57,000 kilograms / year Olly Hater Separator Sludge 3,800 kilograms / year Boiler Firebox Haste 500 cubic feet (generated infrequently)

The levels of radioactivity in the wastes are expected to decrease progressively with time and to be less than the values stated below.

Co 60 <10 pCi/gm Cs 137 <10 pC1/gm Sr 90 <1 pCi/gm Transuranic alpha activity <10% of total activity.

In accordance with 10 CFR 20.302(a), PGandE requests approval to dispose of /

the subject wastes as produced without individual authorization. PGandE cill

~

sample the waste and ensure that the radioactivity in the waste does not exceed the levels evaluated in the radiological assessments presented in our earlier submittals which were appreved by NRC (refer to Attachments I and II). Furthermore, if greater than background levels of radioactivity are detected in the wastes, PGandE will adhere to the NRC approved disposal procedure for the wastes. Solid material will be transported directly to IT Corporation's Benicia, California disposal site using approved hazardous waste haulers. Sludges will be transported to IT Corporation's Martinez, California site, placed in evaporation ponds, and evaporated to a suitable dryness. The resulting dried materials will be buried in the Benicia hazardous waste landfill . Final coverage of the landfill will consist of a multilayered, impervioJs, soil cover at least 30 inches thick.

Additional information regarding this application is provided in the following ,

three enclosures:

Enclosure 1 - Evaluation of Radiological Hazard - Oily Hater Separator Sludge Enclosure 2 - Evaluation of Radiological Hazard - Hastewater Pond Sludge and Boiler Firebox Haste Enclosure 3 - Evaluation of the Environment at IT Corporation Class I Disposal" Sites L

l Mr. H. R. Denton  !

PGandE Letter HBL-86-023 June 17, 1986 .

Page 3 l An application fee of $150 is provided pursuant to 10 CFR 170.  !

Questions regarding this application should be directed to Mr. Rudy Uba at !

(415) 972-6577. '

Kindly acknowledge receipt of this material on the enclosed copy of this  !

letter and return it in the enclosed addressed envelope. .

Sincerely, t Enclosures (3) cc: P. B. Erickson l J. B. Martin i Humboldt Distribution '

Service List 0873S/0045K/RHS/1401 m

PGandE Letter No.: HBL-86-023 ENCLOSURE 1 EVALUATION OF RADIOLOGICAL HAZARD OILY WATER SEPARATOR SLUDGE Excerpted from October 27, 1983 letter from J. O. Schuyler, V.P. Nuclear Power Generation, Pacific Gas and Electric Company, to H. R. Denton, Director Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory i Commission,

Subject:

Humboldt Bay Power Plant, Unit No.

3 Very Low-Level Radioactive Haste Disposal.

I l

0873S/0045K

ENCLOSURE 1 EVALUATION OF RADIOLOGICAL HAZARD OILY HATER SEPARATOR SLUDGE The radiological hazard from the contaminated sludge was evaluated for several dose pathways and scenarios, both normal and accidental. The evaluation was based on the isotopic analysis reported in Table I. This analysis identified four radionuclides with concentrations above those found in a control sample of soil from Eureka, California -- cobalt-60, cesium 134, cesium-137, and thorium-234. After correction for background levels, conversion to a volume basis, and averaging, the nuclide concentrations in the sludge are:

Concentration Conc. over Background Ratio Nuclide (uCi/cc) (uCi/cc) to MPCw.i

~

Co-60 7.85 x 10-6 7.83 x 10-6 .262 Cs-134 9.09 x 10-8 7.89 x 10-8 .002 Cs-137 4.55 x 10-6 4.52 x 10-6 ,113 Th-234 5.66 x 10-7 2.41 x 10-7 .012 The background levels were removed so that the concentration of each nuclide could be compared with the maximum permissible concentration above background (MPC) reported in 10 CFR 20, Appendix B, Table II. The HPC in water for insoluble species was used for comparison because the sludge has no credible airborne pathway, and because the sludge is a precipitated sediment and therefore insoluble. Average rather than maximum values were used because the sludge hauling truck holds far more than one bed, and because the truck will be filled alternately from beds in OHS #1 and OHS #2.

The last column of the table above (Ratio to HPCw,1) shows that if the sludge were a liquid instead of a semi-solid, it could be discharged without 10 CFR 20 restrictions.

Normai Non-Accident Exoosure Rates The highest exposure rate of any normal scenario is found one meter from tne mid-point of the tank truck hauling the sludge. Using the concentrations listed above (including background) and the dimensions of the largest sludge hauling truck, this rate was estimated as .0048 mrem /hr. Other exposure rates, e.g., to the truck driver and the disposal site workers, are far lower. Thus, external radiation exposure from the sludge was determined to be insignificant. There are no normal scenarios that result in internal exposure.

Accidental Excosure Rates Two accident scenarios were examined for their dose potential. The first was a postulated spill during sludge handling or transport. The second was the postulated leaching of the material from the waste disposal facility.

0873S/004SK 1-1

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In the first scenario, a sludge spill would pose a potential hazard to the driver, and also to the public in the vicinity if the spill were not confined. The hazard to people on the scene would not credibly lead to an inhalation or ingestion exposure, and any surface contamination could be washed off without consequence. If the spill were unconfined, contamination of a drinking water source could occur. The internal dose to an individual after drinking such contaminated water was estimated by comparing the nuclide concentrations in the sludge to those given in 10 CFR 20, Appendix B, Table II, as shown in the above table. The average waste is assumed to contaminate a drinking water source. The nuclide concentration in the water is conservatively estimated to be 1% of that in the sludge, due to dilution and the insolubility of the sludge. Thus, it is estimated that the whole body dose to an individual, from a chronic exposure to this drinking water, would be 0.4% of the Part 20 limit, or 2.0 mrem / year.

Finally, potential release of the contaminated sludge from a Class I disposal facility was considered with respect to radiological impact. As in the ,

previous scenario, contamination of drinking water is the principal pathway.

Tne dose to an individual drinking contaminated water would differ from the previous scenario in two ways. First, the sludge would be diluted by other wastes (non-radioactive) present in the disposal facility. This would be in addition to the dilution provided by the drinking water source. Second, the disposal facility contains natural and engineered barriers to prevent offsite release of the wastes which reduce both the probability and consequences of such a release. These two differences indicate a lower radiological exposure for the disposal facility release than for the transportation spill accident.

We estimate this dose to be less than 1 mrem / year to an individual.

0873S/0045K 1-2 l

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(

TABLE I ,

i ISOTOPIC ANALYSIS OF OILY HATER SEPARATOR SLUDGE (conc. in4Ci/gm, /'- density of medium, gm/cc)

Date of Analysis 11/04/82 i TOTAL

1. 1 OHS #2 ONS #1 OHS #2 OHS ACTIVITY Soil Sample Isotope Bed /-1.03 Bed /'-1.03 S_ ump /'-1.007 Sumo /-1.007 mci )

• From Eureka l 1.9010.06x10-6 9.86 0.1x10-6 1.86 0.06x10-6 9.28 0.7x10-7 155.0 2.6 0.54x10-8 137Cs 1.4 0.37x10-8 7.34 1.4x10-8 1.55 0.3x10-7 5.43 2.2x10-8 <1.38x10-8 3.1 134Cs 1.64+0.07x10-6 1.72 0.02x10-5 1.99 0.1x10-6 7.96+0.2x10-6 267.8 <3.9x10-9 60co 19.3 3.19 0.48x10-7 234Th 5.33 3.1x10-7 <5.38x10-7 4.75 3.4x10-7 <7.55x10-7 3.69 1.6x10-7 <2.97x10-7 <4.19x10-7 <4.14x10-7 5.47+0.71x10-7 226Ra -

212Pb 1.77 0.3x10-7 2.24 0.4x10-7 1.53 0.3x10-7 <3.44x10-8 2.32 0.09x10-7 214Pb 1.99 0.5x10-7 3.34 0.9x10-7 2.23 0.6x10-7 NOT DETECTED 2.14 0.16x10-7 2.27 0.8x10-7 NOT DETECTED NOT DETECTED NOT DETECTED 2.87 0.38x10-7 228Ac 8.8 0.6x10-8 20871 6.62il.6x10-8 6.62 2.9x10-8 3.62 1.5x10-8 NOT DETECTED 2.09 0.3x10-7 4.23 1.3x10-7 1.75 0.3x10-7 NOT DETECTED 2.78 0.79x10-7 214Bi 40g 3.50 0.3x10-6 3.62 0.3x10-6 2.55 0.3x10-6 <l.22x10-7 2.58 0.12x10-6 Gross alpha ** 1.4+0.2x10-6 0.7+0.2x10-6 Approximate Height, gm 1.46x107 1.17x107 4.28x106 4.28x106 3.486x107 i

i

Approximate Volume, cc 1.42x107 1.14x107 4.25x106 4.25x106 3.41x107

• 0f nuclides found above the background sample concentrations.

a

• • Analysis was performed using " Standard Methods for the Examination of Hater and Hastewater," Part 703 for gross alpha (Published by American Public Health Association, American Hater Horks Association and Hater Pollution Control Federation).

4 i

l 0873S/0045K 1-3

PGandE Letter No.: HBL-86-023 ENCLOSURE 2 EVALUATION OF RADIOLOGICAL HAZARD WASTEWATER POND SLUDGE AND BOILER FIREBOX WASTE Excerpted from April 25, 1985 letter (PGandE Letter No.:

HBL-85-016) from J. D. Shiffer, VP Nuclear Power Generation, to H. R. Denton, Director Office of Nuclear Reactor Regulation, U. S. Nuclear Regulatory Commission,

Subject:

Humboldt Bay Power Plant, Unit No. 3 Very Low-Level Radioactive Waste Disposal.

f 0873S/0045K

ENCLOSURE 2 1 EVALUATION OF RADIOLOGICAL HAZARD WASTEHATER POND SLUDGE AND BOILER FIREBOX HASTE A composite sample of each waste was analyzed for radioactivity. The following nuclides and activities were detected:

ACTIVITY IN ACi/am(I)

DATE OF ANALYSIS 12/27/84 HASTEWATER TREATHENT FIREBOX ISOTOPE POND SLUDGE DEPOSITS -

K-40(2) 3.19 .86 x 10-6 3.68 .44 x 10-6 Co-60 1.06 .14 x 10-6 5.15 .52 x 10-7 Sr-90 <1.0 x 10-7 3.39 2.10 x 10-7 Cs-134 1.28 .40 x 10-7 <3.0 x 10-8 Cs-137 6.11 .43 x 10-6 3.90 .35 x 10-7 U-233, 234 1.20 .14 x 10-6 1.23 .14 x 10-6 U-235, 236 3.88 7.76 x 10-8 6.17 1.42 x 10-8 U-238 9.38 1.12 x 10-7 1.28 .14 x 10-6 Pu-238 7.94 3.81 x 10-9 9.40 5.92 x 10-9 Pu-239, 240 2.42 .68 x 10-8 9.40 5.92 x 10-9 Ra-226 4.48 1.03 x 10-7 2.39 0.17 x 10-6 (1) Dry weight activity, 171. solids content.

(2) Naturally occurring nuclide, not included in dose calculations.

0873S/0045K 2-1 i

l i

Four exposure pathways were examined and several dose calculations were l performed. Results are given below. The four pathways are:

o External exposure from surface-deposited waste o External exposure from a transport truck o Ingestion of food grown at disposal site o Inhalation of resuspended solids at disposal site External Exoosure from Surface-Decosited Haste A hypothetical employee of the disposal site was assumed to stand on the disposal field. He is exposed for 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> per year. A plane radiation source was modeled using Reference 1, to calculate dose. The surface activity of this source was calculated assuming the top 10 cm of sludge or firebox deposits contribute all the surface dose. Self-shielding of the sludge or firebox deposits was not taken into account. Self-shielding would reduce the calculated dose. The estimated annual doses from the sludge and fire deposits ,

were 0.75 mrem and 0.45 mrem, respectively.

External Exoosure from a Transoort Truck The dose rate around a 5,000 gallon tank truck, filled with the wastes, was calculated. The truck was modeled as a cylindrical radiation source. The dimensions are, radius: 0.9 m, length: 7.6 m. A dose rate of 0.01 mR/hr was calculated at 100 cm from the midpoint of the length. Similarly, the dose rate around a 20-ton dump truck filled with firebox deposits to a height of 0.61 m was calculated. The truck was modeled as a rectangular radiation source with dimensions of 6.1 m length, and 2.4 m width. A dose rate of

.00004 mR/hr was calculated at 100 cm from the midpoint of the length. Based

! on this calculation, this pathway will not lead to significant exposure of any individual or group.

Incestion of Food Grown at Discosal Site It is not necessary to calculate doses from this pathway. The absorption of radionuclides by the plant roots would be an inefficient mechanism of radiation exposure. At most, a small percentage of the deposited radionuclides would be absorbed by plants in one growing season. Furthermore, the fraction of material taken up declines rapidly in subsequent growing seasons. An area that had enough soil contamination to produce unacceptable doses by plant uptake and ingestion of food plants would be forbidden already by other restrictions, including, for example, external irradiation.1/

Thus, the dose from this pathway would be a small fraction of the doses from the other three pathways.

Inhalation of Resusoended Solids at Discosal Site Plant employees working at the disposal site are susceptible to internal exposures if resuspended solids are inhaled. Dosp; from this pathway were calculated using a resuspension factor gf 10-7/ c M', dose conversion factors, and breathing rates for adults 4/. Solids from the top 1.0 cm of sludge would be available for resuspension. Horker exposure is 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> per 0873S/0045K 2-2

year. Exposure to the sludge would result in a committed annual dose of 3.1 mrem to the lungs and 3.3 mrem to the bone. Exposure to the firebox deposits would give an annual dose of 7.4 mrem to the lungs and 7.0 mrem to the bone.

References

1. U.S. NRC, Reactor Safety Study, Hash-1400, Appendix VI, Pages 8-9 to 8-14.

2. U.S. NRC, Regulatory Guide 1.109, March 1976.

4 e

4 0873S/0045K 2-3

PGandE Letter No.: HBL-86-023 ENCLOSURE 3 EVALUATION OF THE ENVIRONMENT AT IT CORPORATION CLASS I DISPOSAL SITES Excerpted from April 25, 1985 letter (PGandE Letter No.:

HBL-85-016) from J. D. Shiffer, VP Nuclear Power Generation, to H. R. Denton, Director Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commission,

Subject:

Humboldt Bay Power Plant, Unit No. 3 Very Low-Level Radioactive Haste Disposal.

i i

0873S/0045K l

ENCLOSURE 3 EVALUATION OF THE ENVIRONMENT AT IT CORPORATION CLASS I DISPOSAL SITES This enclosure provides environmental information on the proposed disposal of the Humboldt Bay Power Plant sludga at IT Corporation's Class I disposal facilities as outlined in 10 CFR 20.302(a). It is expected that the waste will be processed at IT Corporation's Martinez, California site where solid will be separated from liquid waste. The liquid will be evaporated to atmosphere. The solids, including heavy metals, will be buried at IT Corporation's Benicia, California Disposal site. This enclosure includes:

o a description of the proposed manner and conditions of disposal; o an evaluation of the disposal site environment, including its topography, geology, and meteorology; o an analysis of groundwater and surface water flows in the general area, and their uses; o a description of nearby land,uses and facilities; o a description of procedures and plans for minimizing the risk of unexpected or hazardous exposure, including the site's emergency plan, its closure plan, and its post-closure plan.

The information contained in this enclosure, unless otherwise referenced, was either provided directly to PGandE by IT Corporation as is contained in the

" Operation Plan for Hazardous Waste Class I Disposal Site at Benicia (Site Operation Plan)" or submitted by IT Corporation to the State of California Department of Occupational Health Services in August 1983.

Manner and Conditions of Discosal (at Martinez. California Site)

Unless PCB is detected, liquid sludges will be treated at IT Corporation's Martinez Treatment plant where heavy metals will be precipitated. A centrifuge will then be utilized to separate the solid and liquid phases.

Solids will be hauled to Benicia for disposal and liquids discharged to the Martinez solar evaporation ponds.

Liquid sludges containing acceptable levels of PCBs will be discharged directly to Benicia's evaporation ponds. To protect against overflows during heavy rains, the evaporation and storage ponds at Martinez and Benicia are required to maintain a freeboard specified in the facility's Haste Discharge Requirements. Once a pond is filled, the contents will be evaporated to a

" dryness" condition with the consistency of a heavy moist solid. Therefore, there can be no evolution of dust from these " dried" bottoms. Finally, the bottoms will be transferred to the landfill, covered with clean fill, and compacted.

l 0873S/0045K 3-1

Toooaraohv The Benicia disposal site is located in a region of low hills between San Pablo Bay and the Suisun Marsh. The site elevation is above the flood plain and ranges from approximately 280 feet to 850 feet above sea level. The site is reached by a single private road which branches off a secondary road two miles from Interstate Highway 680. Figure 1 shows the location and topography of the site.

Geoloav The disposal site is underlain by marine sedimentary beds of Cretaceous age.

The beds consist primarily of impermeable, shaley claystones interbedded with thin lenses of sandstone and limestone. The sandstone is very fine-grained, of low to moderate hardness, and blocky. Because the fractures in the sandstone are tight below the weathered zone, the sandstone is believed to j have a very low permeability along fractures and bedding planes, as well as .

through the grain. Thus, all of the permeability (basicallylessthan10gnderlyingstrataareofverylow cm/sec). This is an essential feature of the site.

The Cretaceous claystone has weathered into a permeable zone varying in thickness from a few inches to several feet. The weathered zone grades upward into a clay topsoil, which meets the stability and permeability requirements of the State Hater Resources Control Board if compacted to 90% of maximum density.

Meteorology Climate and air quality at the disposal site are greatly influenced by westerly and northwesterly winds blowing from San Pablo Bay and the Sonoma Valley. A wind rose map for the site is attached. The site is in the Bay Area Air Quality Management District, which maintains monitoring stations in Concord, nine miles from the site.

Groundwater Hydroloav No aquifer is presently underlying the site.1/ The water bearing zones below the surface have very low permeabilities and do not yield significant.

water to wells or springs. Therefore, groundwater flows should be slow, and migration of fluids to any unidentified deep water bearing zones below the investigated depth would require very long periods of time.

Chemical analysis has shown that the water in monitoring wells is similar to water extracted from the soil, and is unaffected by the waste from the pond nearest the wells. This indicates that the chemical makeup of the groundwater is determined by the petrochemistry, not by leaching from the waste ponds.

I As defined by the EPA in 40 CFR 260.

0873S/0045K 3-2 l

No usable groundwater underlies the site, and the only wells on or near the site are monitoring wells.

Surface Water Hydroloav The site is contained in a single watershed, which is interrupted by a lower site dam for containment of all wastes in the event of pond containment failure. The dam is approved, certified, and inspected by the California Bureau of Dam Safety.

The site receives approximately fourteen inches of rainfall per year. Runoff from all waste handling areas is contained within the onsite surface impoundments until evaporated. Runoff from non-waste areas is diverted around the disposal areas to the lower site dam or to an offsite drainage system.

The water behind the lower site dam is tested, treated if necessary, and discharged under a National Pollutant Discharge Elimination System permit.

The offsite drainage system is sampled monthly to verify water quality. .

No public or private water supply is connected to the facility, or fed from the site's watershed. t Nearby Land Uses and Facilities The disposal site is situated 3/4 mile from the nearest public roadway. It is i surrounded by two barbed wire fences, one around the active portion and the other around the buffer zone. The access road and the active portion fence i'

are posted with signs. Access is controlled by a key card gate in the buffer zone fence. The private access road then passes in front of the facility office in view of the office personnel. The gate is padlocked when the site is unattended. The facility office and maintenance building are the only structures on site. Both are located 100 feet from the nearest waste pond.

The area around the disposal site is wooded and generally uninhabited. There is a small farm 0.6 miles from the edge of the site, at the mouth of the next canyon to the west. Interstate Highway 680 passes one mile east of the site boundary at its closest point. There are an oil refinery and industrial parks approximately 1.5 miles south of the site. The nearest urban center is the town of Benicia (population 18,233), approximately four miles south of the site.

! Emeraency Resoonse

The Site Operation Plan includes a " contingency plan" to minimize hazards to human health and the natural environment while responding to any emergency.

The plan includes:

o a facility description; o names, telephone numbers, and pager numbers of the emergency coordinators; i

t 0873S/0045K 3-3

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o names and telephone numbers of nearby public agencies with emergency response roles; o procedures for response to releases, fires, explosions, personal  !

injuries, and equipment damage; o procedures for cleanup and restart after a release; o locations of fire extinguishers, telephones, and protective equipment; o specifications and instruction manuals for protective equipment; o checklist for inspections after any severe natural phenomenon or event;

)

o site evacuation plan. .

Closure and Post-Closure Plans  ;

The Site Operation Plan provides a site closure plan which was developed in '

accordance with state and federal regulations. The closure plan is intended to minimize long term control and maintenance of hazardous material, and to eliminate all threats to human health or the natural environment. i As the landfill expansion occurs, most of the ponds will be emptied and incorporated into the expanded landfill areas. The closure of the landfill area will be a continuous process over the 35 year design life of the facility. Pond areas which are outside of the final footprint of the landfill will be decontaminated. Closure will be performed on an annual basis on those portions of the landfill that have reached maximum elevation. Final coverage of the landfill will consist of the following components in descending order:

Soil Cover Geotextile Drainage Layer Synthetic Cover Liner Clay Cover Post-closure activities will continue for thirty years after closure. A written post-closure plan has also been designed by the site operator in accordance with state and federal regulations to maintain the integrity of the certified compliance of closure. The activities will consist of quarterly groundwater monitoring, maintenance and monitoring of the waste containment systems, and annual report to the state and Environmental Protection Agency.

0873S/0045K 3-4 l

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Topogrsp. - Orientation: On the ocuth oide of a hill clong e.ain ridgelina

,y*n s,couchern Solano County. The local topography forces the prevsiling vest-southwest vinds to shift to vest-northwest.

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