ML19350B460

Forwards Plan for Implementing Mussel Monitoring Program Requirements in Cp.Excavation for Discharge Diffuser Tentatively Scheduled for Oct 1981.Prediffuser Const Monitoring Will Be Initiated in Near Future

ML19350B460
Person / Time
Site:	Hartsville
Issue date:	03/13/1981
From:	Mills L TENNESSEE VALLEY AUTHORITY
To:	Eisenhut D Office of Nuclear Reactor Regulation
References
NUDOCS 8103200577
Download: ML19350B460 (7)

Text

.i 400 Chestnut Street Tower II March 13,1981 g,g 0

C MAR 191991 >- j lu mesma assuren Mr. Darrell G. Eisenhut, Director -

Division of Licensing T /.[

U.S. Nuclear Regulatory Comission y , . j. t '"'

Washington, DC 20555

Dear Mr. Eisenhut:

In the Matter of the Application of the ) STN 50-518 Tonnessee Valley Authority ) STN 50-519 STN 50-520 STN 50-521 Enclosed is TVA's plan for implementing each monitoring requirement of the mussel monitoring program described in Attachment C of the Hartsville Nuclear Plant Construction Permit (CP) dated May 9,1977.

This plan is intended to clarify several points in Attachment C of the CP. Excavation for the discharge diffuser is tentatively scheduled to comence in October 1981. TVA has obtained an Endangered Species Permit from the U.S. Fish and Wildlife Service enabling TVA to conduct the required monitoring effort. Pre-diffuser construction monitoring will be initiated by TVA in the near future. This monitoring should provide valuable information in determining existing mussel numbers and environmental conditions in the river to evaluate if the requirements established in the CP are applicable under present river conditions.

.In accordance with the CP, TVA will give a three-week notice to the NRC staff, the Intervenors, the U.S. Fish and Wildlife Service, the EPA, and the State of Tennessee before the initiation of dredging ac tivity.

Very truly yours, TDINESSEE VALLEY AUTHORITY h DA \

L. M. Mills, Manager Nuclear Regulation and Safety Enclosure cc: See page 2 Coc) 8103200577 A

-- _ = _ - - . - _ _ - _ _ _ - _ . - .

Mr. Darrell G. Eisenhut, Director March 13,1981 cc (Enclosure):

Mr. Kenneth E. Black

. Regional Director

, U.S. Fish and Wildlife Service P.O. Box 95067 ,

Atlanta, Georgia 30347 '

Mr. Leroy J. Ellis III, Esq.

Chancery Building 421 Charlotte Avenue Nasnville, Tennessee 37219 Mr. Gary Meyers Executive Director TWRA P.O. Box 40747 Ellington Agricultural Center Nashville, Tennessee 37204 Dr. Robert J. Neff Associate Professor Department of Molecular Biology Vanderbilt University Nashville, Tennessee 37203 Mr. Robert B. Pyle, Esq.

Suite 204 1700 Hayes Street Nashville, Tennessee 37203

, Mr. Howard Zeller, Acting Director Enforcement Division U.S Environmental Protection Agency Region IV 345 Courtland Street, NE Atlanta, Georgia 30308

Enclosure PRE-DIFFUSER CONSTRUCTION

1. " Square meter grid sa=ples will be collected along approx 1=ately 30 transects at 50-foot intervals approximating those established during the Dece=ber 1976 mussel survey. The number of quadrats established on each transect will depend on the width of the mussel bed at that particular transect. The square meter grid will be placed on the bottom at approxi=ately 20-foot intervals and all mussels will be care-fully removed and examined and immediately returned to the river.

This reassessnent of the =ussel bed prior to the initiation of dif fuser construction is necessary because a visit to the Cumberland River and Hartsville site in July 1977 revealed that mussels were being removed ,

from the Dixon Island mussel bed by co==ercial mussel fishermen."

TVA ce= ment: This work will be conducted during mid-su==cr 1981 by scuba divers exactly as specified above. Results of the survey will be used as follows: (1) to quantitatively and qualitatively describe the mussel f auna on the Dixon Island bed in order to determine if mussel fishermen have significantly affected these populations since the comprehensive survey of 1976 and (2) to map concentrations of mussels on the bed for use in place =ent of sediment traps.

2. " Prior to the initiation of instream construction activities, sediments in the area of diffuser construction and downstream will be sampled and characterized as to particle size and total volatile solids.

This will provide a baseline of data for evaluating the depostirn 3f sediments resulting from the excavation activities. The follouing procedures will be followed for this activity:

A. Core sampler will be utilized.

B. Ivo transects will be established at the site of dredging--10 sa=ples will be taken.

C. Three transects will be established'on the Dixon Island mussel bed--

15 samples will be taken."

TVA comments: This work will be conducted during late winter or early spring 1981 following above procedures. In addition to the purpose stated in item I under Post-Dif fuser Excavation Period, these data will be used to determine if river flow can be regu-laced to control sedimentation by controlling water velocities in the vicinity of Dixon Island mussel bed and to determine flow rates which best flush sediment from the Dixon Island mussel bed.

3. " Chemical constituents of the sediments will be determined prior to the diffuser construction. An elutriate test will be perfor ed to detect any significant release of contaminants in the material to be dredged.

Six samples will be collected in the area to be dredged and 3 samples will be collected on the Dixon Island mussel bed. Sa=ples will be analyzed for Hg, Pb, As, Cd, Cu, Zn."

TVA co==ent: Samples for these analyses will be collected at the same locations as those in Ite= 2 above, and analyses will be performed following standard procedures. Results of thess tests will be used to deter =ine if changes in construction procedures should be considered.

4 " Sedimentation trapa will be placed by Scuba divers at specified intervals along the length of the Dixon Island =ussel bed downstream of the proposed dredging operation to esti= ate the loss of and acce=ulation of =aterials in the sediments (to be continued throughout the instrea= dredging ac tivJ. ties) . A control station (1 transect) upstres= of the dredging operation will be monitored to detect natursi sedi=entation rates for co=parative. ourposes." ,

TVA co==ent: Sediment =easuring devices are currently being designed by TVA engineers. Once designed, tested, and constructed in sufficient nu=bers, devices to measure sedinent depth will be placed by scuba divers upstrea= of the dredge site and on the Dixon Island =ussel bed. This will probably occur during =tuau==er 1981. The nu=ber

of traps to be used and exact place =ent locations will be deter-

=ined af ter cespletion of sedi=ent characterization and pre-dif fuser excavation mussel survey. These results will provide information on natural sedi=entation at upstrea= and downstrea:

locations as well as infor:ation on botto= lead sediment transport.

5. " Scuba divers will search the area from Dixon Islanc downstrea= to the upper edge of the Dixon Island =ttssel bed and re=ove any isolated nussel speci= ens. Any speci= ens found will be placed on or in the substrate of an established =ussel bed."

TVA co==ent: During =idsu==er 1981 scuba divers will wearch the area fro = CuRM 284.1 to Dixon Island for isolated mussel specimens, re=o-a these specimens, and place the= on the Dixon Island =ussel bed (i.e., the nearest =ussel bed).

DIFFUSER EXCAVATION PERIOD

1. " Prior to initiation of the dredging activity, the Per=ittee shall give three weeks written notice of the planned construction schedule to the NRC Staff, the Intervenor, the U.S. Fish and Wildlife Service, the U.S.

Environ = ental Protection Agency and the State of Tennessee."

TVA co= cent: Notifications will bc =ade as specified.

2. " Sedimentation traps will continue to be placed at the sa:e stations used in the pre-diffuser excavation period. The traps will be returned twice per 3-hour dredging crew working shif t (once after 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and once after S hours) during excavation of approxi=ately the first 1,000 cubic yards of =aterial. Additional sedi=entation traps will be placed at the same stations to provide a =easure of the aggregate (total) deposi-tion of silt which results from the construction activity during the excavation period. Applicant will deter =ine the depth of sediment deposited in the traps. If one-quarter inch or = ore aggregate sedi=ent

3 l .

is found to have been deposited in at least two sa=ple traps, dredging

vill be stopped. Dredging may be resumed if later observation of sedi-ment traps shows that the aggregate sediment deposition has been reduced i

. to less than one-quarter inch. Before using any artificial means to re=ove the sediment, Applicant will obtain the concurrence of the Department of Interior."

k TVA co==ent: Various sediment trap designs are currently being

); evaluated. The design which appears most promising is best described as a tray rather than a trap and uses ultrasonic freq-uencies to measure depth of sediment accumulated on the tray. If this design is selected, scuba divers will place trays at the same locations used in Item 4 under Pre-Diffuser Construction.

The trays will then be checked every four hours as specified--it ,

will not be necessary for scuba divers to return the trays to surface since this design will provide a surface " read out" from a deck or shore unit. All trays will be monitored throughout  !

t instream dredging, l,

! Sediment tray results during the Diffuser Excavation Period will ,

be compared to results from the Pre-Diffuser Construction Perfod i to document differences in sediment deposition between the two

periods. If sedi=ent accu =ulation en at least two trays on the Dixon Island mussel bed is 1/4 inch or = ore, dredging vill be '

stopped. Dredging will be resumed when sediment depth decreases below 1/4-inch.

I 3. " Turbidity levels of the river above and below the dredging activities l

will be measured at 1-meter depth intervals from surface to the bottom and averaged over the water colu=n to document changes in i natural turbidity levels resulting from these activities. Samples will be taken hourly during excavation.' Natural turbidity levels of record 4

as defined in the Hartsville Nuclear Plant's ER will be the feedback criteria for regulating the rate of instreas dredging. Maximum docu-

- mented levels of turbidity are 85 ppm (JTU)." l L

LTVA comment: Turbidity measurements at 1-eeter depth intervals

, upstream of the diffuser dredge site will document natural or base-l .line- turbidity levels during the period of instream dredging.

Turbidity measurements downstream of the diffuser construction site will provide information on.the increase in turbidity result-

ing f rom construction activity. Turbidity will be measured at- a j midpoint on .the Dixon Island mussel bed approxi=ately 600 feet ,

downstream of the dredge site. If turbidity increases cause the

downstream reading to exceed 85-JIU, then the rate of dredging i may be slowed, although the controlling criterion will be a 50 percent reduction in the depth of 0.1 percent of the light trans-mission with reference to an upstream control as specified in. item 4 below.

I

- 4. . " Measurement of light intensity in the vater colu=n will be perfor=ed ,

!- with a submarine. photometer both above and below the dredging activi- I k

. ties. Measurements will be made hourly during excavation. A 50

- percent reduction in the depth of 0.1 percent of the light trans-

~ mission at some selected point'at the mussel bed' relative to an i 4

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_4 upstream location (above the dredging activities) will be the feed-back criteria for instituting corrective mitigative acuisns."

TVA comment: Light transmissibility measure =ents will be made hourly at a control point upstream of Dixon Island and at a mid-point on the Dixon Island mussel bed approximately 600 feet down-stream of the construction site. If a 50 percent reduction in the depth of 0.1 percent of light transmission relative to the upstream control occurs, corrective action will be initiated to comply with the above criterion.

5. "Should the aggregate silt deposition or turbidity levels or light pene-tration data indicate a need for mitigative action, the inspector will report his findings and make his reco==endation to the praject environ-mental engineer, who will present these findings and rectne.endations to the project =anager. The project manager will make the caeision on the citigative actions to be taken, i.e. , to slow down or halt construction."

TVA co==ent: These directives will be followed.

6. " Dissolved oxygen, pH, conductivity, and te=perature profiles will be made at upstream and downstream locations to document any perturbations of these parameters."

TVA ce==ent: These parameters will be monitored every four hours at the same locations as light intensity measure =ents (see Item 4 in this section). These results will be evaluated and reported as specified in item 8 below.

7. "During blasting activities, mussels will be placed by scuba divers at established intervals from the area of the blasting to deter =ine if mussels on the Dixon Island bed are harmed by shock waves from these activities. No threatened or endangered species vill be used."

TVA comment: If blasting is required, ten specimens of a non-endangered mussel species will be placed at 10-foot intervals, starting at a point 10 feet from the blast out for 100 feet.

Holes will be drilled for blasting charges to reduce blasting effects.

8. "Within 30 days after completion of the dredging activity, the Permittee shall submit to the NRC Staff a su==ary report of the results of the monitoring plan with copies to the Intervenors, the U.S. Fish and Wild-life Service, the U.S. Environmental Protection Agency and the State of Tennessee."

TVA comment: As directed, the su==ary report will be sub=itted -

'vithin 30 workint days after co:pletion of dredging activity.

POST-DIFFUSER CONSTRUCIION

1. "A post-diffuser construction survey of sediments in the area of the ditruser and mussel bed will be conducted to document any perturbation of river sediments as a result of these construction activities. A total of 5 samples will be collected from each of three transects approxi-mating those established in Pre-diffuser construction (2)."

TVA co==ent: A core sampler will be used to collect samples for particle size and total volatile solids from the same locations on the Dixon Island mussel bed that were sampled in the Pre-Diffuser ,

Construction period (see Item 2 of that section). The two transects within the excavation corridor sampled during Pre-Dif fuser Construc-tion will not be sampled during Post-Dif fuser Construction. This is the area that has been dredged and backfilled with rock. This work will be performed as soon af ter completion of instream construc-tion at conditions and scheduling permit.

2. " Transects approxima ting those established during the pre-dif fuser con-struction survey will be established at 50-foot intervals beginning at the upper end of the mussel bed (CRM 284.1). Square acter sangjas will be taken along the transect. Mussels recovered from the square meter grids will be carefully removed and examined and i==ediately returned to the river. This qualitative and quantitative data will serve as.a reevaluation of the mussels found on the Dixon Island mussel bed following completion of the diffuser construction activities."

TVA comment: This survey will be conducted by scuba divers as specified above after completion of discharge diffuser construction.

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