ML19338B992

Forwards Review of Geologic & Hydrologic Aspects of Proposed Facility Per AEC Request

ML19338B992
Person / Time
Site:	Midland
Issue date:	05/07/1970
From:	Radlinski W INTERIOR, DEPT. OF, GEOLOGICAL SURVEY
To:	Price H US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 8007291141
Download: ML19338B992 (5)

Text

. __

m t

3 e,

A 't 7

~;

UNITED STATES lI DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY

~

' ' ' ~

WASH I N GTON. D.C.

20242 gy 7 1970 Mr. Harold Price Director of Regulation U.S. Atomic Energy Commission 7920 Norfolk Avenue Bethesda, Maryland 20545

Dear Mr. Price:

Transmitted herewith in response to a request by Mr. Roger S. Boyd, is a review of the geologic and hydrologic aspects of the Midland Plant Unit Nos. 1 and 2 - AEC Docket Nos. 50-329 and 50-330 - proposed by the Consumers Power Company.

This review was prepared by H. H. Waldron and P. J. Carpenter and has been discussed with members of your staff. We have no objections to your making this review a part of the public record.

Sincerely yours, y

g?,j.uw1LJ-((,.d(. ( C i. ActingDirector Enclosure ec: Walter G. Belter, AEC + 80072syy Y/ TmS' DOCUMENT CONTAINS 1414 . POOR QUAUTY PAGES

_s e. 3 Midland Plant Units Nos. 1 & 2 ~ Consumers Power Company AEC Docket Nos. 50-329 and 50-330 The planned location for the Midland Plant Units Nos. 1 & 2 is on the south shore of the Tittabawassee River at the southern city limits of Midland, Midland County, Michigan.. The plant is bounded on the west by Bullock Creek-drainage area, approximately 40 square miles..The plant will use two pressurized water nuclear reactors each rated at an ultimate output of 2,552 megawatts tnermal, ano a combined oucput of approximately 1,300 megawasta electrical. An artificial cooling pond will be used as a storage reservoir and as a heat sink for the condenser cooling water. The following ccaments concerning the geology and hydrology of the site are based on an independent analysis of the data presented by the applicant in the " Preliminary Safety Analysis Report" and " Amendments" as well as an -independent check of other available data and literature. The site was vicited on Auguct 14, 1969, and February 11, 1970. The analyses as pre-sented by the applicant appent to adequately appraise those geologic and hydrologic conditions pertinent to the safety evaluation of the site. Gee'ocv The site is located in the Caginaw Lowland portion of the Great Lakes section of the Central Lowland physiographic province. At the. site a crystalline basement complex is overlain by more than 12,000 feet of nearly flat-lying Paleozoic sedimentary rocks, and by about 360 feet of glacial sediments. chiefly fine grained glacial lake deposits. Bedrock at the sitc consists of shale and interbcdded sandstone and siltstone of the Saginaw Formation of Pennsylvanian age. The applicant proposes to excavate the upper layer of loose cand, whd.ch ranges in thickncss from a few inches to as much as 35 feet, and to found the containment structure on the underlying very stiff to hard, preconsolidated, lacustrine clay unit, which ranges in thickness from .130 to 190 feet. All other major plant etructures will ba founded either on ~ this hard clay unit or on compacted fill, or partly on both. Tectonically the site is situated near the center of the Michigan Dasin, a major regional structural basin that underlies the southern peninsula of Michigan and parts of adjoining ctatec. Although there are no active faults or other recent geological structures known in the area that could be ex-

.cted to localize seismicity in the i==ediate vicinity of the site, struc-tural details in the underlying Paleozoic sedimentary rocks or in the crystalline basement complex are only very poorly known. Several structural featuras of a lesser magnitude have been mapped or.have been postulated to exist within the Michigsu Basin. Most of these features are ancient, north-west-trending enticlinal, synclinal, or monoclinal structures that have been g e qo ogppg 14 o

M oMuJulbh

's r delineated as a result of extensive oil and gas investigations. The site arca appears to be located on one of these minor features locally known as the 'hidland Trough"; the axial trace of the closest anticlinal structure 33 approaches to within about 10 to 15 miles southwest of the site. Although ~ normal faulting is reported to be associated with some of these structures, especially-those in the southern part of the basin, none has been reported in the vicinity of the plant site. Most of the deformation apparently took place in early Paleozoic time. Deformation is greatly diminished to absent in the younger Paleozoic -rocks, and none of these secondary features is known to extend to the surface or to have disrupted any of the glacial deposits in !!ichigan. Natural brines and salt have been and st!.11 are.being removed from a brine aquifer and from beds of salt that occur in the Detroit River Group (Devonian) at depths ranging from about 4,100 to 5,100 feet in the vicinity of the proposed nuclear power plant. The plant site overlies the projected eastern extremity of this brine and salt producing area. Although curface subsidence due to the extraction of natural brines appears to be precluded by the methods used in the extraction process, detailed studies and analyses by the applicant indicate that some very minor, broad, trough-type surface sub-sidence may occur in the site area due to solution mining of the salt bcds; the effects at the actual plant site, however, will be very small, and surface rupture due to subsidence will not occur. In order to still further assure the safety of the plant, however, it is recommended that a precise monitoring system be installed for the purpose of detecting the occurrence of and determir.ing the amounts of any possible future surface displacements that might occur.due to subsidence in the plant area. i Hydrolonv ^ The plant grade will be established at elevation 634 feet above mean sea level. The stage for the Tittabawassee River probable maximum flood, as - computed in 1956 for Dow Chemical Company, is given as 632 feet above mean sea. level. The discharge of the computed probable maximum flood-270,000 cubic feet per second-included a flow of 20,000 cubic feet per se:end re-sulting from the breaching of four upstream low-head dams. Tais discharge r + is approximately 7.8 times greater than the maximum flood of record (34,800 cubic feet per second; March 28,1916; stage, 610 feet above cean sea level) and is appro3 mately 2.2 times greater than the maximum discharges observed i for nearby, like-si=ed, drainage basins which appear to exhibit-a similar extreme-flood potential. The applicant has independently reevaluated the probable maximum flood, dam breaching and the resultant stage at the plant site. _The results of these reevaluations, as given by the applicant in discussions, are near Sut slightly below those originally presented. In addition, the applicant has evaluated the probable maximum' flood and corre-sponding stage for' Bullock-Creek occurring simultaneously with a 100 year flood-flow on the Tittabawassee River. The results of the reevaluation: 2-

= e A ? ,,3 w for Tittabawassee River and the Bullock. Creek study were not made available in final form for our technical evaluation prior to this review. However... from discu'ssions with the. applicant it can be stated that the computational-procedures'used. appear to be appropriate and the applicable hydrologic-parameters appear.to have been evaluated and applied correctly; if so, the ~ final results should be-reasonable. In any event, the applicant has stated ~ that he " agrees.tc provida whatever additional flood protection, if any, is required in_accordance with the revised probable maximum flood computations." It should be noted that the estimate of the probable maximum' flood is the ^ result of a theoretical calculation dependent on available meteorologic and hydrologie data. As more such data becomes available this estimate could be -revised upward. An emergency cooling pond will be constructed in an exacavation in the cottom of the operating cooling pond. The applicant states that if, the operating cooling pond dikes were to fail the emergency pond could provide the amount of ecoling water needed for 30 days of plant shutdown without make up water from the Tittabawassee River. It is our understanding that after 30 days the re-quired amount of make-up water would be less than 2 cubic feet pr second. The minimum instantaneous flow observed on the Tittabawassee River (period of-recerd, 1936 to 1966) was 39 cubie feet per second and the minimum daily flow t*rr 111 cubic feet per second. Assuming that the integrity of the emergency coolins pond can be maintained in case of failure of the dikes of the operat-o ing cooling pend, an adequate supply of make-up water for safe shutdoun of the pla.nt cppears to be assured. The applicant has stated that operationally produced radiocctive liquids will be released at maximum permissible ~ concentrations specified in 10 CFR 20 to the Tittabawassee River and only under extreme or emergency conditions will radioactive liquids be discharged to the cooling pond. Further, such dis-charger to the pond'will be at a level to insure that 10 CFR 20 concentration j limite in the pend are not exceeded and prior to such dischar8es, detailed j analyses of the potential radionuclide concentration and possible aquifer cen-tamination will be made available for' review and acceptance ' by the ' Division of Regulation, Atomic' Energy. Commission. The applicant hac stated that the radioactive waste system is contained with-in Cle:s 1 structurcs,.and accidental liquid relce:cs due to cempere : or piping failuree would be contained within these structures. No estimates of the ceount'and composition of potential ~ accidental radioactive liquid die-charges have been made.. The Tittabawassee River'immediately downstream from Midland apparently is~not'used for. domestic or municipal water supplies but is used mainly as an industrial water supply. The nearest downstream

municipal water supply appears :to be located in Saginaw Bay, some 40 to 50 miles downstream.

9 3 ~ => T

^ ....t, 4 It should be mentioned that the Water Resources Commission, State of Michigan (1960) has stated that the water requirements in the Midland ZI area for' cooling, processing, and waste assimilation have already ex-ceeded the supply. Consequently, all liquid waste discharges from the plant should be restricted to as low a level as is practically possible. ~ Assuming that future ground-water developments do not alter significantly the hydraulic gradients or head relationships in the aquifers under the site, ground-water supplies of the area should not be affected by accidental sellia of radicacti.c liquidu for the folt'uf s rennene: (1) the hydraulic gradients in the shallow water-table aquifer, as de-termined by borchole observations, are toward the Tittabawassee River, (2) all dome: tic wcils dug or drilled into the wacer-tcbie aquifer in the area apparently are located upgradient of the site, (3) a relatively impermrable clay layer, some 130 to 190 feet thick, separates the water,- table aquifer and the underlying artesian aquifer which furnishes petable water supplies, (4) data from a pump test show that the piezometric sur-face of the artesian aquifer is above the water table, and (5) all wells in the cooling pond area will be effectively filled end scaled by the applicant to prevent fluids from entering the aquifers directly. Re ferene_e_: Water Resources. Commission, State of Michigan, 1960; Water Resources Conditions and Uses in the Tittabawassee River Basin. W G e b 4 0}}