ML19323E256

Forwards Flood Insurance Study & Seven Oversize Drawings in Response to 800505 Ltr to Hydrologic Engineering Questions Re Executive Order 11988

ML19323E256
Person / Time
Site:	Sequoyah
Issue date:	05/20/1980
From:	Mills L TENNESSEE VALLEY AUTHORITY
To:	Schwencer A Office of Nuclear Reactor Regulation
Shared Package
ML19323E257	List: ML19323E256 ML19323E259
References
NUDOCS 8005230276
Download: ML19323E256 (10)

Text

, _ __ _ _ _ - _ _ - _ _ _ _ _ - _ - - _ _ _ _ _ _ - - _ _ _ _ _ _ _ _ _ _ _ -

e g. s TENNESSEE VALLEY AUTHORITY CH ATTA NCOG A. TENN ESS EC 37 *.01 400 Chestnut Street Tower II M.y 20, 1980 Director of Nuclear Reactor Regulation Attention: Mr. A. Schwencer, Chief Light Water Reactors Branch No. 2 Division of Licensing U.S. Nuclear Regulatory Commission Washington, DC 20555

Dear Mr. Schwencer:

In the lhtter of the ) Docket No. 327 Tennessee Valley Authortiy )

.

Enclosed are 10 copies of the additional information that you requested in Enclosure 2 of your letter to H. G. Parris dated May 5, 1980, entitled, " Hydrologic Engineering Questions Relating to Executive Order 11988 Floodplain Management."

If you have any questions, please get in touch with C. L. Mills of the Environmental Planning Section of my staff at FTS 854-3331.

Very truly yours,

'

TENNESSEE VALLEY AUTHORITY

/

L. M. Mills, Manager

• Nuclear Regulation and Safety '

,

N Enclosures (10)

(\0[b

• p

._

- - - . .

POOR QUALITY PAGES r

An E::ual O::criamty Eme. M' 8005230 2 7g

- - - - .- . _ . - - . _ . - .-_

- .. ,

• Enclosure i

i l '

Hydrologic Engineering Questions

. Nos. 1, 2, and 3 Relating to

.

Executive Order 11988, Floodplain Management

) _

I- Definition (from Executive Order 11988 Floodplain Management)

Floodplain: The lowland and relatively flat areas adjoining inland and coastal waters including floodprone areas of offshore islands, 1 including at a minimum that area subject to a one percent or greater chance of flooding in any given year.

Question 1:

Provide descriptions of the floodplains of all water bbdies, within or

'

adjacent to the site. On a suitable scale map provide delineations of l those areas that will be flooded during the one-percent chance flood.

Provide details of the methods used to determine the floodplains. Include l your assumptions of and bases for the pertinent parameters used in the computation of the one-percent flood flow and water elevation. If studies l approved by Flood Insurance Administration (FIA), Housing and Urban Develop-

! ment (HUD) or the Corps of Engineers are available for the site or adjoining I area, the details of analyses need not be supplied. You can instead provide the reports from which you obtained the floodplain information.

!

i l Response:

The only stream adjacent to the Sequoyah site is the Tennessee River.

l There are no streams within the site. The one-percent chance floodplain I of the Tennessee River at the site is delineated on figure 1. Details

! of the analyses used in the computation of the one-percent chance flood flow and water elevation are described in the study " Flood Insurance Study, J

Hamilton County, Tennessee, (Unincorporated Areas)" made by TVA for FIA and published in February 1979. A copy of this report and the floodway, flood boundary, and floodway maps are being provided. The section that describes the hydrologic and hydraulic analyses is on pages 6-9, page 22 lists references, and figure 02P shows the Tennessee River profiles.

Question 2:

Identify, locate on a map, and describe all structures in the floodplain.

Response

i i The only structures located in the one-percent chance floodplain are j transmission towers, the intake pumping station skimmer wall, and the ERCW pump station deck. The ERCW pumps are located on the pump station

,

deck at elevation 705.5, well above the one-percent chance flood level.

l These structures are shown on figure 1.

I v-- , -, . + , - _ , , . _ , , _ _ . . , _ _ _ _ . . .... - . _ - , , , , , - - . - , , .

-

. . _ . - __

~ _ .

i

.. -. . .. . )

4

)

Question 3:

I Discuss the hydrologic effects of all items identified in 2. above.

Discuss the potential for altered flood flows and levels, both upstream and downstream. Include the potential effect of debris accumulating on the plant structures. Additionally, discuss the effects of debris generated from the site on downstream facilities.

.

Provide the details of your analysis. The level of detail is i

similar to that identified in item 1. above.

1 i

,

Response

The structures that are located in the floodplain will not alter 1 flood flows or elevations. The 20,650-square-mile dra'inage area is not altered and the reduction in flow area at the site is infinitesimal and at the fringe of the flooded area. The site will be well maintained and any debris generated from it will be minimal and will present no problem to downstream facilities.

• Attachments

!

l

<

s

(

.

._ . . ._ -.

.

~ m.

l DOCJ -

~

_.

pumus

,

-

A G. ~  :

annus m ammum l

\

'

l A O.8-2-c NO. OF PAGES l REASON:

O PAGE ILLEGIBLE:

CF O HARD COPY FILED AT:

OTHER i

/ 1  !

O BETTER COPY REQUESTED ON GE TOO LARGE TO FILM.

PDR CF O HARD COPY FILED AT:

l OTHER ED ON APERTURE CARD NO. 3005230 r1L M be$ k,-o6

__

--- --- - _ _ _ -____ - _ _ _ _ _ _ ___