ML19344E971

Requests Addl Info Re Permanent Dewatering Sys Proposed for Site Per Hydrologic & Geotechnical Engineering Branch Review

ML19344E971
Person / Time
Site:	Midland
Issue date:	08/27/1980
From:	Tedesco R Office of Nuclear Reactor Regulation
To:	Jackie Cook CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
References
NUDOCS 8009120199
Download: ML19344E971 (11)

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,...,g UNITED STATES

,,e NUCLEAR REGULATORY COMMISSION o

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% * * * * * /e August 27, 19P2 i

l Docket Nos. 50-329 THIS DOCUMENT CONTAINS and 50-330 POOR QUAUTY PAGES l

i Mr. J. W. Cook Vice President l

Consumers Power Company j

1945 West Parnall Road l

Jackson, Michigan 49201

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION REGARDING DEWATERING OF MIDLAND SITE Amendment No. 74 to your application dated February 28, 1980, provided a

infomation regarding a pamanent dewatering system proposed for the Midland site in response to Request No. 24 frem Mr. L. Rubenstein's

.j letter of November 19, 1979. The review by the hydrologic section of 4

our '..'ydrologic and Geotechnical Engineering Branch indicates the need i

for further information regarding that response as identified in This information is in addition tc related requests contained in our letter of August 4,1980.

l We would appreciate your reply to Enclosure 1 at your earliest opportunity.

Should you need clarification of these requests for additional information,

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please contact us.

Sincerely, E

9.A.c,D Robert L. Tedesco, Assistant Director for Licensing S

Division of Licensing u.. closure:

g Request for Additional c

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• Informatien cc w/ encl:

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.8009120.

I l-r August 27, 1980 i

Mr. J. W. Cook' E

Vice President o

Consumers Pcwer Company 1945 West Parnall Road j

ll Jackson, Michigan 49201 cc: Michael I. Miller, Esq.

Isham, Lincoln & Beale Suite 4200

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1 First National Plaza 4'

D Chicago, Illinois 60603

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Judd L. Bacon, Esq.

Managing Attorney Consumers Power Company 212 West Michigan Avenue Jackson, Michigan 49201 Mr. Paul A. Perry, Secretary Consumers Power Ccmpany i

212 West Michigan Avenue Jackson, Michigan 49201 Myron M. Cherry, Esq.

1 IBM Plaza i

Chicago, Illinois 60611 Ms. Mary Sinclair 5711 Sumerset Drive Midland, Michigan 48640 l

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Frank J. Xelley, Esq.

Attorney General State of Michigan Environmental p

Protection Division 720 Law Building Lansing, Michigan 48913 Mr. Wencell Marshall Route 10

[l Midland, Michigan 48640 y

o Grant J. Merritt, Esq.

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Thompson, Nielsen, Klaverkamp & James 4444 105 Center

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80 Scuth Eighth Streat

Minneapolis, Minnesota 55402 f

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i Mr. J. W. Cock 2-August 27, 1980

. cc: Mr. Steve Gadler l

2120 Carter Avenue.

l St. Paul, Minnesota-55108.

Mr. Don van Farewe, Chief Division of Radiological Health Departrent of Public Health-P. O. Box 33035 Lansing, Michigan 48909

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William J. Scanlon, Esq.

i 2034 Pauline Boulevard Ann Arbor, Michigan 48103 U. S. Nuclear Regulatory Commission

• Resident Inspectors Office Rcute 7 Midland, Michigan 48640 R

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. August 27, 1980 cc:. Cc:wendce, ?!aval Surface !! capons Center ATTN: lP. C. Huang 6-402

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!:r. L. J. Auge, f*anager Facility Design Engineering Energy Technology Engineering Center P. C. Box 1449 Canoga, Park,-California 91304 Mr. William Latthcad U. S. Corps of Engineers f;CEED - T

7th Ficor 477 Michigan Avenue Detroit, Michiga.: 48226 f's. Earbara Stamiris t.

5795 N. River-Freeland, Michigan 4S623 f:r. Michael A. Race 2015 Seventh _ Street P.ay City, Michigan 48706 Ms. Sandra 0.' Reist 1301 Fourth Street Gay City, Michigan 48706 Ms. Sharen R. Warren 036 Hillcrest l

Midland, Michigar. 48640 Patrick A. Race

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1(104 N. Sheridan Gay City, Michigan 4S706 Crerge C.1lilson, Sr.

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S.'t;inaw, Nichigan 48603 t

Ms. Carol Gilbert' 903 N. 7th Street Saginau, Michigan 48601 I

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ENCLOSURE 1 SUPPLEMENTAL RECUESTS REGARDING PLANT FILL

. 49. Your response to our Request 24 states that if the dewatering system should fail, more than 90 days would occur befc:>e groundwater levels would rise to elevation 610 feet, the groundwater elevation at which liquefaction would become a problem. We are concerned that this water level rise might occur over a period considerably less than 90 days in view of the following apparent discrepancies in equations and input parameters:

a.

The error function solution to the partial differential equation describing unsteady groundwater flow which you used to detemine permeability, appears to be incorrect; the correct form should have a 4 in the denominator, instead of a 2 as you have shown. The correct equation is:

h=H 1-erf x

d4Kht/n e where:

h = water level rise at X=0 i

H = water head at X=0 5 = average depth of water error function erf

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permeability i

X=

distance

.t = time l

ne= effective porosity l

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. b.

In the above equation since h is the average depth, its value should lie between h and H.

In. applying this equation to compute a permeability K of 11 feet per second ar.d a corresponding rebound time of 90 days, you used 0.1 foot for h,1.6 feet for H, but 20 feet for h. ' Use of a smaller value of h (somewhere between 0.1 and 1.6 feet) would result in a higher permeability and a rebound time considerably shorter than 90 days.

c.

Your value for x in the above equation is 325 feet, which you say is the shortest distance between the critical area and the recharge source, i.e., the distance between the southeast corner of.the diesel generator building and the southwest corner of the-circulating water intake structure. However, Figure 24-1 shows this distance to be about 240 feet. Use of this smaller value for x will also result in a rebound time shorter than the 90 days which you have computed.

l (1) Please justify or correct the above apparent discrepancies and, if appropriate, provide revised analyses to better define the l

rebound time to be expected following a prolonged dewatering l

system failure. A more conservative analysis might involve utilizing the recovery data from the appropriate puma tests, i.e., K = 31 fps.

(2) In determining rebound time, it is our position that you should l

also postulate failure of non-Seismic Category I piping at critical locations. This should include the circulating water l

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. (3) Demonstrate that there remains cdequate time to install and implement a back-up dewatering system to prevent groundwater from rising above elevation 610 feet.

50. Your Response to Request 24 concludes that there is groundwater recharge from the cooling pond in the araa of the intake and pump structures because pumping tests at well PD-15A resulted in very lettle drawdown at observation wells SW-1, SW-4 and RR-1.

However, for several indicated reasons, you also concluded that there is very little recharge in the area of the discharge structure and one of these reasons is that there is very little drawdown at observation wells PD-3 and PD-203 as shcwn by Figure 24-14. These appear to be contradictory conclusions (i.e., how can very little drawdown indicate recharge at one location and no recharge at another nearby location?).

Provide additional information to support and clarify ycur conclusion that there is negligible recharge in the area of the circulating water discharge structure.

(Also see related Request 17(2)).

51. Ycur response to Request 24 regarding the area weil dewatering system concludes that 22 wells pumping at an average rate of 5 gpm would be needed to remove grounewater stored within the backffil and natural sands. Two more wells are :rovided for infiltration and pipe leakace.

You have not demonstrated whether 24 wells wculd also be a sufficient numoer to maintain the area groundwater at the desired elevation felicwing removal of tne groundwater already in storage. Provide additional information to demonstrate that 24 wells will maintain groundwater levels below elevation 610 feet and provide the design basis used for this determination. Additionally, justify your use of 14 percent for an average Significant Yield Coefficient.

52. Your response to Request 24 discusses the source of groundwater which you have determined from pumping tests in the vicinity of the Service Water Pump Structure and the Circulating Water Intake and Discharge Structures. However, no tests appear to have been concucted to determine if Ocw Chemical's Tertiary Water Treatment Pond, shown on FSAR Figure 2.1-1 A and located just west of the nuclear plant, represents a potential source of groundwater. We are aware of your conclusion that inflow of groundwater from outside the plant area is precluded by the cooling por.d dike which enccmpasses the nuclear plant site; however, you have provided no information to support this conclusion with respect to the Dow pond. Also lacking is information on the details of your West Plant Dike shown on FSAR Figure 2.5 46.

Provide ir.#armation to demonstrate whether the Dcw pond it nr will be a source of groundwater at your plant site. As a minimum, include the following:

(1) provide a general description of the Ocw pena (size, depth, capacity, purpose, contents, sealing method, etc.). Specify maximum elevation of the water in the Ocw pond with relationship to the groundwater level below the plant.

Include a sketch shcwing distances and elevations of the Ocw pond relative to the West Plant Dike.

. (2) Provide details on your West Plant Dike. Ccmpare the West Plant Dike to your cooling pond dike, including any similarity in their quality of construction and their source of construction materials.

It appears that plant excavation extended to the area where the West Plant Oike is located; discuss whether and how excavation for the plant affected construction of the West Plant Dike.

(3) Provide as-built drawings of the Wes,t Plant Dike.

(4) Provide the results of any tests conducted to reach a conclusion on the effect c the Dow pond on the groundwater beneath the plant.

(5) If the Cow pond is a potential source of groundwater, provide analyses of the chemistry of this water (both present and future) and describe its effects on the dewatering system and other under-ground ccmponents (piping, tanks, etc.).

Identify any agreements or plans you have to monitor and control the contents or influence of the Dow pond during plant operation.

(5) Provide groundwater elevations in the warehouse a-ea which is located Letween the Ocw pond and the West Plant Dike.

53. Your discussion of the interceptor well system design in response to Recuest 24 assumed that seepage would flow into a 400 fco slot located 150 feet frem the cooling pond. You assumed nat part af tnis slot would be ineffective because the intake and pump structures would cut off part of the seepage from the cooling pond. To account for tnis cut off, you assumed that the slot would be located 450 feet from the cooling pond instead of 150 feet. This assumption reduced the cuantity of inflow to ne slot.

. Figures 24-9 and 24-10 indicate that 5 to 10 feet of natural sand exists below the intake and pump structures (See Request 47(3)).

Consequently, these structures may not cut off or reduce the seepage from the cooling pond. You should therefore recompute total ground-water inflow without any reduction for the structures and recompute the number of interceptor wells required. Reposition and space wells accordingly. Alternately, provide additional information to support your conclusion that the structures serve as positive cut offs.

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