Text

Forwards Responses to 800307 Hydrologic Engineering Questions Re Waste Treatment Sys,To Assist NRC Environ Review of Unit 2.Affidavit Encl
	ML17272A943
Person / Time
Site:	Columbia, Washington Public Power Supply System
Issue date:	04/25/1980
From:	Renberger D; WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	Sells D; Office of Nuclear Reactor Regulation
References
	GO1-80-123, NUDOCS 8005050293
	Download: ML17272A943 (22)
	v • d • e

t REGULATORY INFORMATION DISTRIBUTION SYSTEM t (RIDS)

ACCESSION NBR:8005050293 DOCODATER 80/04/25 NOTARIZEDR YES DOCKET FACIL;50 397 HPPSS Nuclear Projectg Unit 2P Hashington Public Powe 05000397 50 460 HPPSS Nuclear Projecti Unit ii Washington Public Powe 05000060 50 513 WPPSS Nuclear Projecti Unit 4P Hashington Public Powe 05000513 AUTH INANE,. AUTHOR AFFILIATION RENBERGERPD ~ LE Nashington Public PoWer Supply System RECIPRNAME RECIPIENT AFFILIATION SELLSPD,E, Environmental Projects Branch 2

SUBJECT:

Forwards responses to 800307 hydrologic engineering questions re waste treatment sysito assist NRC environ review of Unit 2.Affidavit encl.

DISTRIBUTION CODE: ROOTS COPIES RECEIVED:LTR i ENCI. i SIZE:

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NIISo5o g g Washington Public Power Supply System A JOINT OPERATING AGENCY P. O. BOX 958 3000 GEO. WASHINCTON WAY RICHLAND, WASHINCTON 99352 PHONE (509) 375 5000 April 25, 1980 G01-80-123 Docket Nos. 50-397 50-460 50-513 Mr. Donald E. Sells, Acting Chief Environmental Projects, Branch 2 Division of Site Safety and Environmental Analysis United States Nuclear Regulatory Agency Washington, D.C. 20555

Dear Mr. Sells:

Subject:

WPPSS NUCLEAR PROJECTS NOS. 1, 2 AND 4 HYDROLOGIC ENGINEERING UESTIONS

Reference:

GI2-80-49, letter, D. E. Sells to D. L. Renberger, Dated March 7, 1980 Attached are the responses to your hydrologic engineering questions with respect to the proposed waste treatment system for the WPPSS 1, 2, and 4 plants. We trust that this will provide you with the required information for your environmental review of WPPSS 2.

Very truly yours, D. L. Renberger Asistant Director, Technology DLR:ACR mch Attachments cc: Nick Reynolds, Debevoise 8 Liberman

$g5001 (h

l k,c~T STATE'F'WASHINGTON)

) ss PPSS NUCLEAR PROJECTS, NOS. l, 2 AND $

HYDROLOGIC ENGINEERING QUESTIONS COUNTY OF BENTON D. L. RENBERGER, Being first duly sworn, deposes and says: That he is the Assistant Director, Technology, for the WASHINGTON PUBLIC POWER SUPPLY SYSTEM, the applicant herein; that he is authorized to submit the fore-going on behalf of said applicant; that he has read the foregoing and

=knows the contents thereof; and believes the same to be true to the best of his knowledge.

DATED r~ l g2, lgGG D. L. RENBERGER On this day personally appeared before me D. L. RENBERGER to me known to be the individual who executed the foregoing instrument and acknowledged that he signed the same as his free act and deed for the uses and purposes therein mentioned.

GIYEN under my hand and seal this ~g nc day of , 1980 ota y Publsc in and for t State of Washington Residing at

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ATTACHMENT A HYDROLOGIC ENGINEERING QUESTIONS WPPSS-2 AND 1/4 SEWAGE TREATMENT FACILITY

1. PRIMARY LAGOON guestion:

Provide additional information regarding the liner that will be used to prevent seepage from the primary lagoon. This information should include liner permeability, liner strength, and durability construction techniques, and bases for the values reported.

Response

The liner which will be used to prevent seepage in both the primary (aerated) ponds and the secondary (stabilization) ponds will be a 20-mil polyvinyl chloride (PYC) membrane. It will be installed over a prepared subgrade, then covered with 12 inches of native material for sunlight and tear protection.

The liner itself is virtually impermeable to the passage of water.

Minor leaks along seams and through small tears and pinholes are, of course, unavoidable. The specifications call for the contractor to field test the completed ponds for leakage. The maximum allow-able leakage during this field test will be 1/4-inch per day.

The strength and durability characteristics of the liner are listed on attachment B. Construction techniques are shown on attachment C.

2. SECONDARY LAGOON guestion:

Provide the basis for your estimate of 1/4-inch per day of seepage from the secondary lagoon. Discuss the treatment of the lagoon sides and bottom that will be used to achieve this seepage limit.

Document that buildup of salts and other solids on the bottom of the secondary lagoon will not adversely affect the quality or quantity of the seepage from this pond.

Page Two HYDROLOGIC (UESTIONS AND RESPONSES

Response

The 1/4-inch per day rate is not an estimate of the leakage rate from the secondary (stabilization) ponds; it is the maximum allow-able by Washington State Standards. The actual leakage rate will be much lower than this. Rather than use a bentonite liner, it has been decided that a PVC liner will be used in the secondary ponds.

This liner will be identical to the type used in the primary ponds.

Our experience has shown that the leakage through this type of liner is virtually undetectable if proper construction procedures are followed. The organic sludge which will build up on the pond bottom will have a tendency to seal the bottom and reduce leakage through any small holes or tears in the liner. The chemical character-istics (salts) of any seepage through the sludge will be essentially the same as in the wastewater overlying the sludge blanket; a semipermeable membrane (similar to those used in reverse osmosis units) between the sludge and wastewater would be necessary for them to develop dissimilar chemical characteristics. The problem to which you refer with heavy metals and salts buildup in sludges is associated with mechanical treatment plants. In these plants, the sludge is separated from the main wastewater stream; digesting and dewatering increases the chemical concentrations. This problem does not occur with lagoon systems.

3. OVERFLOW LAGOON guestion:

Document the design bases for overflow into the third lagoon due to intense rainfall. Discuss the frequency of- rainfall that will be contained and the methods of computation of the required storage volume.

Response

Rainfall is not ordinarily considered as a design parameter for the flow patterns within lagoon systems. There are two reasons for this:

a) The normal variations in pond depth far exceed any rainfall considerations. The secondary ponds are designed to have a depth varying between three and five feet. This is accomplished with an adjustable outlet weir. The ponds and piping between them have been designed to handle a one-foot variation in depth (i.e., a drop from five-foot level to four-foot level or 1.5 million gallons) within a 24-hour span. The one percent storm will yield a 24-hour precipitation event of only about 2.4 inches, or 300,000 gallons well within the design capacity.

Page Three HYDROLOGIC QUESTIONS AND RESPONSES b} All lagoons within the plant are designed with three feet of freeboard above normal maximum water levels. The 2.4-inch increase in level caused by the one percent storm wi 11 be safely contained within the freeboard.

ALL THREE PONDS Question:

Provide responses to the following generic questions.

a) Provide descriptions of the floodplains of all water bodies, including intermittent water courses within or adjacent to the site. On a suitable scale map provide delineations of those areas that will be flooded during the one-percent chance flood in the absence of plant effects (i.e., pre-construction floodplain).

Response

The flood history of the Hanford Reach of the Columbia River is discussed in Section 2.4 of the WNP-2 FSAR. The derivation of critical flood elevation and the references utilized are reported therein. The Standard Project Flood (SPF) has been defined by the Army Corps of Engineers as 570,000 cfs, which represents a 367 ft. MSL elevation at the WNP-2 intake. The makeup water pumphouse operating floor elevation is 375 ft.

MSL. The lowest elevation of the Sanitary Waste Disposal System is 414 ft. MSL at the percolation beds. The one-percent flood represents 650,000 cfs and 370 ft. MSL elevation at the WNP-2 intake (please see Attachments D and E, which are respectively, Figure 2.4-3 of the WNP-2 ER-OL and Figure 2.4-14 of the WNP-2 FSAR). Attachment F shows the topographic detail of the site vicinity.

b) Provide details of the methods used to determine the flood-plains in response to a) above. Include your assumptions of and bases for the pertinent parameters used in the computation of the one-percent flood flow and water elevation. If studies approved by Flood Insurance Administration (FIA), Housing and Urban Development (HUD) or the Corps of Engineers and avail-able for the site or adjoining area, the details of analyses need not be supplied. You can instead provide the reports from which you obtained the floodplain information.