ML20209C932
| ML20209C932 | |
| Person / Time | |
|---|---|
| Site: | Satsop |
| Issue date: | 05/08/1984 |
| From: | Johnston W Office of Nuclear Reactor Regulation |
| To: | Novak T Office of Nuclear Reactor Regulation |
| References | |
| CON-WNP-1452 NUDOCS 8405180386 | |
| Download: ML20209C932 (17) | |
Text
't
.;!E G E84 Docket No. 50-508 l
MEMORANDUM FOR:
Thomas M. Novak, Assistant Director for Licensing, DL FROM:
William V. Johnston, Assistant Director Materials, Chemical & Environmental Technology, DE
SUBJECT:
HYDROLOGIC ENGINEERING INPUT TO THE WNP-3 FES Plant Name:
WPPSS Nuclear Project No. 3 Licensing Stage: OL Responsible Branch:
Licensing Branch No. 3; V. Nerses, PM Requested Completion Date:
April 23, 1984 Attached are our responses to comments received on the WNP-3 DES for your use in preparing the FES.
In addition, we've made several revisions to the text of the DES.
Our input is provided in two enclosures as follows: )
Input to Section 9 of the FES which is titled " Staff Responses to Comments on the Draft Environmental Statement."
l ) Revisions to DES text.
In addition to the comments assigned to EHEB for response, we are also responding to comments WNP 3-22, WNP 3-24, WNP 3-25 and WNP 3-26, which were incorrectly assigned to AEB, and to comments WNP 3-33 and WNP 3-36, which were assigned to LB #3.
The last sentence in comment 3-25 concerns a l
paragraph in the DES that seems to be misplaced.
Since we did not provide input to this portion of the DES, we are not responding to this portion of the comment.
The due date of April 23 was missed because of our belated receipt of certain comments identified above.
i i
8405180386 840508
}
SP ADOCK 05000508 t
W
.L 7 ovo.
s y
[
~,
.)
Thomas M. Novak. l's.1
<?
This input was prepared by R. Gonzales who can be reached on extension 28117.
/
William V. Johnston, Assistant Director Materials, Chemical & Environmental Technology Division of Engineering
Enclosures:
~
As stated I
cc: w/o encl R. Vollmer w/ encl R. Ballard G. Knighton J. Hulman V. Nerses M. Fliegel R. Samworth R. Gonzales DISTRIBUTI0ti:
Mitfckets EHEB Rdg EHEB File IH B
'DE B
E:E.
DE!hb RGonzales:ws MHFliegel RLBa lard WVJohnston 5/f/84 5/p84 5/3 /84 5/ 4/84
1 e,
.-.s e
P e
ENCLOSURE 1 HYDROLOGIC ENGINEERING INPUT TO SECTION 9 0F THE WNP-3 FES
+
O G
O N
J FES - SECTION 8 STAFF RESPONSES TO COMMENTS ON THE DRAFT ENVIRONMENTAL STATEMENT Comment D.I.1 As noted on page 5-51, the accident analysis shows that the plant's passive underdrain system could deliver radioactive sump water to Workman Creek in the event of a core melt accident.
The effects on Workman Creek, Chehalis River, and Grays Harbor, only briefly suggested, could be severe.
The. statement mentions a possible mitigation measure--the sealing of the underdrain, apparently after an accident on page 5-52.
However, it is not clear that the sealing of the drain after the accident can be assured before a major radioactive release has occurred.
The question arises why the underdrain system does not include provisions to shut off or divert to safe storage any contaminated flow from the reactor.
It would 'b'e simpler to provide for tilese measures before an accident has occurred than afterward.
Staff Response to Comment D.I.1 I
The staff believes that there are measures that could be taken to mitigate the liquid release of a core-melt accident to the Chehalis River.
The more feasible measures appear to be sealing of the three 10-inch underdrain outflow.
pipes with concrete or damming of Workman Creek.
However, since we cannot prove conclusively that these mitigative measures would be und.ertaken after I
a core melt accident,"we performed a conservative analysis to determine the effects of the liquid pathway of a core-melt accident.
Conservative assumptions made by the staff in this analysis were as follows:
I j
1)
It was assumed that no effort would be made to interdict the contaminated groundwater.
l 2)
'Ihe underdrain system was assumed to remain intact and fully operational.
In reality, it is likely that at least part of the system would be destroyed in the melt-through of the 15 foot reinforced concrete l
containment basemat.
1
m J
3)
It was assumed that there would be no holdup or dilution in Workman Creek.
4)
It was assumed that 100% of the core inventory of Cs-137, the main.
contributor to risk, would reach the Chehalis River immediately.
1 The staff's conservative analysis showed that although releases via the groundwater pathway would be much larger for WNP-3 than for ' typical U.S. power reactors, the total risk from this pathway would be small when compared to the atmospheric pathway.
The staff does not require that the underdrain system include provisions to shut off or divert to safe storage any contaminated flow from the reactor, because the postulated occurrence of a core-melt accident that would result in a liquid release would involve a sequence of successive failures more severe than those required to be considered in the design bases for protection systems and engineered safety features.
The staff agrees that the effects of such an accident could be severe; however, the probability of its occurrence is_.so.small that its environmental risk is extremely low.
Comment D.I.2 The proposed sealing of the underdrain outflow would retain the highly radioactive water.
The statement should discuss the long-term adequacy of the storage capacity of the underdrain system and should evaluate the system's long-term integrity, if it is used to retain the contaminated sump water.
This evaluation should consider the potential for ground-water impacts if a loss of the underdrain system's integrity should release the contaminated water to the ground-water environment.
Thestatementshouldalsoexplainhowthe passive underdrain system below and in the vicinity of the reactor 'would be protected against damage if the basemat failed.
q Staff Response to Comment D.I.2 The staff stated that the underdrain system could be sealed following a core-melt accident.
However, in analyzing the impact of a basemat melt-through
. the staff assumed a worse case scenario whereby the underdrain system would not be sealed and the contaminated groundwater would reach the Chehalis River immediately.
If the underdrain system were sealed, the contaminated ground-water would move much slower in a northward direction toward the Chehalis River.
In this case, the groundwater pathway would have travel times much greater than those which characterize the small river site in the LPGS.
This would allow time for engineering measures such as slurry walls or wellpoint dewatering to isolate the radioactive contamination near the surface.
Comment 0.I-3 m
The Reactor Safety Study (WASH-1400) includes an analysis of possible depth of penetration of a core-soil mass; heat transfer calculations indicated that this mass would be about 50 feet high.
Thus, the Class-9 accident analysis for
'WPPSS No. 3 should assess the integrity of the underdrain system if 50 feet of penetration should occur.
A sketch of the underdrain system should be provided in the final statement.
l Staff Response to Comment D.I-3 As described above, it was assumed that a melt-through would not affect the function or operability of the underdrain system.
This is a conservative assumption that results in a worse case situation for assessing the impacts on the Chehalis River.
In reality, however, it is likely that the core-soil mass would damage or destroy the underdrain system.
If this were to accu',
t the travel time for contaminated groundwater to reach the river woule be much
g greater.
Likewise, the population dose would be less than for the scenario assumed.
Drawings of the underdrain system are presented in Figures 3.4.1-1 to 3.4.1-5 in Chapter 3.4 of the FSAR.
Comment WNP 3-8 Historical flow data for the Chehalis River are summarized in the fourth paragraph of Section 4.3.1.1.1.
The average Chehalis River flow at the site 3
.is given (without reference) as 6824 ft /sec while the ER-OL and FSAR suggest 3
about 6630 ft /sec.
The average monthly flows cited for August and January 3
should be given as 806 and 14,668 ft /sec, respectively (see FSAR p. 2.4-g; ER-OL p. 2.4-1 and T. 2.4-1 to be amended, accordingly).
The rainimum 3
historical flow is now estimated to be 454 ft /sec (FSAR p. 2.4-51) rather 3
than 397 ft /sec as cited in the DES.
In the third sentence of Section 4.3.1.1.3 it should be noted that the 3
550-ft /sec river flow limitation could be waived by the State based on regional power needs.
Staff Response to Comment WNP 3-8 3
The average river flow given in the FSAR (6630 ft /sec) was estimated by using stream flow data available through 1981.
The staff used data available through 1983. Using the U.S. Geological Survey WATSTORE computer system, average flows were obtained by the staff for the Chehalis River at Porter and for the Satsop River near Satsop.
The Chehalis River at Porter average flow value was then adjusted to a flow value for the Chehalis River just upstream of thd*
confluence of the Satsop River.
This was done by using drainage area ratios.
The next step consisted of adding the average flow value from the Satsop River
-,.,n_
-e..-.
m
/
- to the adjusted average flow value for the Chehalis River to obtain a flow value for the Chehalis River just downstream of the confluence of the Satsop River.
This flow value was then adjusted to the site by again.using drainage area ratios.
This procedure resulted in an estimated average flow in the Chehalis 3
' River at the site of 6824 ft /sec.
3 Average monthly flows cited in Section 4.3.1.1.1 of the DES as 730 ft /sec 3
3 and 14,900 ft /sec, respectively, have been revised to 806 ft /sec and 3
14,668 ft /sec in this FES as suggested in Comment WNP 3-8.
Also, the 3
minimum historical low flow has been revised from 397 ft /sec given in Section 3
4.3.1.1.1 of the DES to 454 ft /sec as suggested in the comment.
3 The portion of the comment referring to the 550 ft /sec river flow limitat. ion has been incorporated into Section 4.3.1.1.3 of this FES.
Comment WNP 3-22 The DES finds that the WNP-3 liquid pathway (p. 5-50 to 5-53) yields doses substanttally greater than the LPGS doses and still poses much less risk than the gaseous pathway. We note that the DES estimates are also much greater than Supply System estimates (RQ240.14).
Both the DES analysis and that of the Supply System begin with the very conservative assumption that 100 percent of the core inventory of cesium, the major contributor to dose, reaches the river immediately, whereas 10 percent would be more realistic.
Given the conservative source term, the large population dose for WNP-3, relative to the LPGS, is derived from conservative assumptions regarding shoreline usage, fish catch / consumption, and river dilution.
Staff Response to Comment WNP 3-22 S
The staff agrees that not all of the cesium in the core-inventory would be released to the Chehalis River.
However, attempting to accurately quantify the amount of cesium that would be released to the surface by the sump water via the underdrain system, is subject to large uncertainties.
In the LPGS, small river site, which was used for comparison with the WNP-3 site, it was assumed that 100 percent of the cesium in the core-inventory would be in the sump water, but because of radioactive decay, only 31 percent would eventually' reach surface waters.
This radioactive decay would occur
~
during the estimated 51 year interval that it would take cesium, which is retarded by its interaction with the soil, to travel through the ground.
For WNP-3 the same assumption that 100 percent of the core-inventory of cesium would be in the sump water was made.
We agree that it is a conservative assump-tion but do not necessarily agree that 10 percent is a more realistic estimate.
The applicant states that, "given the conservative source term, the large population dose for WNP-3, relativa to the LPGS, is derived from conservative assumptions regarding shoreline usage, fish catch / consumption, and river dilution." The staff does not believe that these assumptions for WNP-3 are any more conservative than those used in the LPGS.
Therefore, the main reason that the WNP-3 liquid pathway consequences are more severe than those for the LPGS site is because of the passive underdrain system which would release contaminants to the surface much more rapidly than in the LPGS.
Comment WNP 3-24 The DES analysis (p. 5-52) uses the harmonic mean flow which.is about one-fourth of the annual mean flow of the Chehalis River.
We assume it conservatively neglects the contribution of tributaries downstream.
Because a large fraction of the one million pounds of fish are caught in Grays Harbor, with its associated flushing and dilution, yet another conservatism is inherent in the analysis.
The analysis also neglects any sediment partitioning which would reduce concentrations.
S
J Staff Response to Comment WNP 3-24 Harmonic mean flow (HMF) was used not to neglect the contribution of tributaries downstream as assumed by the applicant but to calculate a conservative dilution
~
value.
The annual mean flow (AMF) was not used to calculate dilution because it is disproportionately weighted by high flows.
Consequently, using the AMF to calculate dilution may indicate higher dilutions than could be expected.
For example, suppose there is an annual stream flow record consisting of 10 months when the flow was 100 cfs and 2 months when it was 10,000 cfs.
The AMF would thus be ((100)(10) + (10,000)(2) + 12) = 1750 cfs.
Using this flow value would result in.a dilution value that is too large because for 10 of 12 months the average flow was only 100 cfs.
Using a HMF to compute dilution minimizes the disproportionate effect of high flows.
The HMF is determinpd by computing the reciprocal average flow for each month.
These are then summed up and divided into the number of months in the period of record.
In the above example where the period of record consists of 10 months of 100 cfs flows and 2 months of 10 000 cfs flows, the sum of the reciprocal average flows is ( h 0 +
) = 0.1002.
Dividing this value into 12 months 10,000 results in a HMF of 120 cfs = (12 +.1002).
Using 120 cfs to compute dilution is thus more reasonable since it is much closer to the 100 cfs 10 month average.
For the Chehalis River at the site, the AMF computed by the staff is 6824 cfs.
The HMF is 1871 cfs.
Using the HMF to compute dilution results in higher population doses and is thus more conservative.
Comment WNP 3-25 In the second and fourth paragraphs on p. 5-51 (the third seems out of place),
it should be noted that the plant underdrains discharge to a Workman Credk tributary which is referred to as Stein Creek (see Figure 5.1).
Workman Creek is not an ephemeral stream.
Also, we acte that the third paragraph on p. 5-56 seems misplaced and perhaps belongs to the discussion of uncertainties on p. 5-63.
1 t
i
}
f j
- r I
e Staff Response to Comment 3-25 The paragraphs in question have been revised to reflect the information
, provided in the comment.
i Comment WNP 3-26 1
In summary of our comments on accidents, we suggest that neither the Staff nor the Supply System has "shown" WNP-3 to have " considerably worse" consequences than the LPGS.
Given the conservatisms of the analysis, a more qualified judge-ment seems appropriate for the last paragraph of Section 5.9.4.5(5).
Staff Response to Comment WNP 3-26 se Because of the many uncertainties concerning core melt accidents; the staff, throughout its analysis, used conservative values and assumptions.
Thus the staff's analysis is conservative and the results can be considered to be upper bounds of the actual values that could be expected.
The objective of the staff's analysis was not to quantify the population dose that would result from a core melt accident and subsequent melt-through of the concrete containment floor.
Rather it was to determine whether the consequences, at WNP-3, could be substantially different, qualitatively, than those associated with a typical land based nuclear power. plant.
Our analysis did show that at WNP-3 there is a potential for a significant amount of radio-activity to enter the surface rather rapidly, a situation that is not typical of the large majority of land based nuclear plants.
We recognize that our analysis depicts an upper bound condition.
Further, we state that althou,gh the liquid pathway consequences would be worse for WNP-3 than for the typical LPGS small river site, they still pose much less of a risk than the airborne pathway.
4
.,,,n-.. -...,_. _ _ _..... - - -
~. _... - -,. - _ - -.,
\\
.g.
Comment WNP 3 33 3
2 On p. 4-13 units of flow are m /sec, not m /sec.
Staff Response to Comment WNP 3-33 The units of flow have been changed to agree with the proposed corrections.
Comment WNP 36 3
On p. 5-3 units of flow are m /sec, not ug/sec.
Staff Response to Comment WNP 3-36 The units of flow have been changed to agree with the proposed corrections.
{
a ENCLOSURE 2 b
REVISIONS TO DES TEXT O
N w.
f I
.:a
l
]
4.3.1.1.1 Surface Water The surface ~ water descriptions in Section 2.5 of the FES-CP are still valid with the inclusion of the new information and discussions below.
In addition,'
Section 5.3.3 of this report addresses the hydrologic effects of alterations in the floodplain in response to Executive Order 11988, Floodplain Management, cnd Section 5.9 contains the analysis of severe liquid pathway accidents.
The WNP-3 site is located in the hills just south of the Chehalis River, the major drainage system in Grays Harbor County and one of the major drainage basins in West Central Washington.
The total drainage area of the Chehalis River basin is approximately 5440 km2 (2100 mi2).
The stretch of the river from its mouth at Grays Harbor to the vicinity of the site (about 32 km (20 miles)) is tidal.
Figure 4.6 is a map of the Chehalis River basin.
The Chehalis River flows generally eastward to the city of Chehalis where it changes course abruptly to the north.
From near Grand Mound, about 16 km (10 miles) north of Chehalis, the river flows northwesterly to Elma then west to Grays Harbor at Aberdeen.
The major tributaries of the Chehalis in the vicinity of the site are the Satsop and Wynoochee Rivers.
The Satsop River has a drainage a 2
of about 57.5 mW, ea of 777 km,(300 mi2) and an estimate average annual flow sec (2030 ft% sec).
The Wynocchee River has a dr inage area 7
of 259 km,2 (100 mi2) and an estimated average flow of about 34.0. /sec 4
(1200 ftVsec).
Figure 4.7 shows the surface hydrologic features in the vicinity of the plant site.
The long-term average flow of the Chehalis River at the site just downstream 3
3 of the Satsop confluence is estimated to be 193 m /sec (6824 ft /sec); the average flows in the Chehalis and Satsop Rivers above their confluence are 3
3 3
3 cbout 133 m /sec (4680 ft /sec) and 57.5 m /sec (2030 ft /sec), respectively.
The estimated average monthly flows in the Cheha_lis River at the site vary m
3
[{ January (ER-OL, JS$ ft /sec) in August to 42Cm /sec (i',^^t.f td/sec) in from~3G 3 m /sec 3
3 SEction 2.4.1); this variability reflects the s~easonal rainf alll distribution within the basin.
The once-in-10 year, 7-day-duration low flow g9 Y k is estimated to be about 15.0 m /sec (530 ft /sec).
The minimum and maximum w
3 3
W D
% historical flows at the site have been estimated by the applicant to be v
3 3
3 3
22:e m /sec ('80iL ft /sec) and 2750 m /sec (97,100 ft /sec), respectively.
LL9 454 The'Chehalis River channel in the vicinity of the site is about 76.2 m (250 feet) wide and varies in depth from approximately 0.3 m (1 foot) during low flow to greater than 10 m (30 feet) during flooding conditions.
The cverage river bed elevation ranges from about 16.8 m (55 feet) below mean sea level (msl) near the mouth to 5.8 m (19 feet) above msl about 16 km (10 miles) upstream of the site.
The velocity characteristics of the Chehalis River are quite variable.
Ou~ king low flow conditions (11.3 a/sec (400 ft /sec)), velocities of about 0.1 m/sec 3
(0.4 fps) are experienced, whereas during flood flow conditions (850 m /sec 3
(30,000 fts/sec)) channel velocities reach 1.8 to 2.1 m/sec (6 to 7 fps).
In addition to fresh water flow conditions, the site hydrology is influenced to some extent by ocean tides.
Flow reversals of the Chehalis River are known to cccur several miles upstream from Montesano over most of the range of discharge; cn the other hand, salt water intrusion is known to extend only a short distance upstream from the Montesano highway bridge and only during low flow conditions.
WNP-3 DES 4-13 C
')
)
Plant grade elevation is about 119 m (390 feet) msl, which is about 113 m Five streams, (370 feet) above the normal water level of the Chehalis River.
all relatively short and intermittent, drain at least some portion of the site. These include Workman, Purgatory, Fuller, Hyatt, and Elizabeth Creeks.
Purgatory and Fuller Creeks were significantly altered by site-erosion-control-runoff-treatment-measures during site construction.
Hyatt Creek and Elizabeth All of these creeks Cr:ck were directly influenced by plant construction.
h va also been altered by lumbering activities which have altered their w tsrsheds.
Table 4.1 shows the characteristics of streams within the influence of the site.
Table 4.1 Characteristics of streams at WNP-3 site i
Watershed area Watershed area Total within plant clearcut from watershed construction 1965 - 1977 Length area Stream (feet)
(acres)
(acres)
(%)
(acres)
(%)
Workman 48,000 7,090 60 1.1 2,690 37.9 Stein 6,700 360 40 11.7 40 11.1 Purgatory 7,000 320 120 37.5 130 40.6 Fuller 12,300 720 230 33.3 220 30.6 Hyatt 10,000 540 60 11.1 260 48.1 Elizabeth 21,000 2,730 10 0.4 520 19.0 Source:
ER-OL Table 2.4-3.
4.3.1.1.2 Groundwater The only satisfactory source of groundwater in the vicinity of the site is in These coarse the sand and gravel aquifers in the Chehalis River valley.
alluvial deposits are up to 61 m (200 feet) thick, and their yields range from Lower yield sources of groundwater 0 )(.8 to 11.4 m / min (200 to 3000 gpm).
3 The groundwater occur in the. Pleistocene terrace deposits north of the site.
d
.in these unconsolidated terrace deposits occurs in pockets of permeable san s and silty sands having low yield; it is adequate only for domestic uses.
l A compilation of data for w' ells within 3 and 32 km (2 and 20 miles) of the,M I
site is in ER-OL Tables 2.1.12 anc' 2.1.13.
The the site because the population density is very low in other directions.
wells are relatively shallow 30 m (100 feet), yielding a few hundred gpm; they The only major consumer of are used for irrigation and/or domestic purposes.
i groundwater in the area is the town of E1ma 6 km (4 miles) northeast of the The nearest well to plant, which can withdraw up to 7.6 m / min (2000 gpm).
3 the plant is about 8045 km (5000 feet) to the north-northwest.
4-16 WNP-3 OES
-)
Watsr for plant op rations is produced from two Ranney well collectors located at about river mile 18.
About 88% of the water collected by the Ranney wells comes from the Chehalis River via infiltration; the rest comes from groundwater
[g in the alluvial valley fill.
A single well is capable of supplying the total
/
3 plant needs of about 68.1 m / min (18,000 gpm).
1 4.3.1.1.3 Supplemental Water Supply 1
The plant is permitted by the State of Washington to withdraw from its_Ranney
?
3 3
wells up to 196,800 m / day (52,000,000 gpd) on a daily basis, ano 183,600 m / day 3
(48,500,000 gpd) on a 30-day average basis.
Withdrawal may not exceed 2.2 m /sec (80 ft /sec) instantaneously; in addition, it may not exceed the difference 3
between the river flow and 15.6 m /sec (550 ft /sec).
When Chehalis River flows 3
3 3
3 are less than 15.6 m /sec (550 ft /sec), normal withdrawals must cease, except that up to 0.1 m /sec (2 ft /sec) may be withdrawn to maintain the plant in a 3
3 i
( not standby condition A The applicant has also made provision to purchase up to 1.8 m /sec (62 fts/sec) of water from the City of Aberdeen's Wynocchee Reservoir 3
to supplement flow in the Chehalis River below the plant during low flow periods.
q This water is to be used to mitigate adverse impacts associated with the. con-Qumptive use of the river water.
Regional Water Use be. tM.IVt) /sec, (550 ftS/sec) fiver -Gour.hdfaHon m 1te15,C,m3 b Oc 5tafe bMed on regional power V18ddS.
4.3.1.2 f
The water resources of the Chehalis River Valley include both ground and su r 7
face supplies.
More than half of the water used in Grays Harbor County is for irrigation.
Water use is controlled by certificate or permit issued by the Washington State ~ Department of Ecology.
Within 8 km (5 miles) of the site, surface water permits have been granted to about 78 users for a combined water l
use of up to 0.7 m /sec (23 ft /sec), mostly for irrigation, with the remainder 3
3 for domestic, livestock watering, fish propagation, fire protection, and industrial uses.
There are no known drinkiiig water users drawing from Chehalis River surface supplies downstream from the plant.
Groundwater wells in the Chehalis River Valley are relatively shallow, usually less than 3 m (10 feet) in depth.
Most of the wells are located on.the flood-plain deposits north of the river.
There are 45 known wells within 3.2 km (2 miles) of the plant, used mostly for. drinking and irrigation.
Five major cunicipal water systems within 32 km (20 miles) of the site are served partially or totally by groundwater.
Some of these systems, notably Montesano and Central Park, may draw on groundwater in contact with the Chehalis River downstream from the plant.
These systems serve populations of 3200 and 2000, respectively.
The staff could not estimate the fraction, if any, of river water that con-stitutes these supplies.
4.3.2 Water Quality The water in the Chehalis and Satsop Rivers has remained at a high level ofe quality (ER-OL, page 24-4, and Washington,1979, page 13).
The applicant conducted extensive sampling for water quality in both rivers and in onsite streams from 1978 through 1981 to document effects of construction on water quality as well as to strengthen the basel.ine data for later evaluation of potential impact of station operation (Envirosphere, 1978, 1980, and 1982).
WNP-3 DES 4-17 h
m
1J e
\\
October the limit is 30 pg/1, if the startup period should include these (Strte Order Number 568, October 8,1979).
months NPDES Discharge Permit (see Appendix G).
These are the limits in the current Tha basis for the State determination that a 65 pg/l limit would provide 20 to 1 would occur before the effluent encountered ar h
ade-col significance.
h At a background concentration of 4 pg/1, a 20-to-1 dilution g-1 woul.d provide a copper concentration of 7 pg/1, which is believed to be a le thot has no effect on the salmonid species.
1 vel Td:quicy of the requirements for copper.Th2 State required that the a J
i(
The applicant has com.pleted the j
e studics.
However, the results have not yet been made available.
5.3.2 Water Use f
e n FES-CP Section 5.2 states that WNP-3 and WNP-5 would have some impac g
1ccal and regional surface water and groundwater.
e p:cted to the tidal portion of the Chehalis River No adverse -impacts were ex-3 of approximately 1.7 -)%/sec (60 ft3/sec) was expec. The consumptive withdrawal l-nacr the plant during low flow conditions and cause some elimination of riffle ted to lower the river level flow in a shallow area known as " Green Banks. '
marsh, causing it to become dry during low flow periods.1cct":
5
'34 ent
- With the cancellation of WNP-5, water use has been approximately cut in half Tha above-stated impacts of water use will be appreciably smaller because of th2 diminished water use.
5.3.3 Other Hydrologic Impacts Flc:dplain Management, was signed in May 1977.Ccnstruction of th c nclusion that consideration of alternative locations for any of the struc-It is, ther i
tur;s identified as being in the floodplain is neither required or practi Tha 100 year flood discharge on the Chehalis River adjacent to the site cable.
d;tcrmined by a study performed by the U.S. Army Corps of Engineers (COE)
, as S sttle District, is 2209 m3/sec (78,000 ft2/sec).
+i struction river geometry.100 y:ar flood varied from 5.8 to 6.1 m (19 to 19.9 fee 3
Cbla ficod on the Chehalis River.The plant itself is located well above any conceiv-
{
b2 Offccted by the 100 year flood would be the discharge structureThe only p
-D well intake structures and associated bank protection, and a barge slip
, the Ranney
%tructures are considered by the staff to be a relatively minor intrusion on These p'
th] flo:dplain of the Chehalis River for which no alternatives are readil por:nt.
p s all loss in habitat.The only likely consequences of these plant related features would y ap' Enstruction 100 year flood levels because of these structures to be (0.2 fcst).
The staff concurs in this evaluation.
~
,1 m
s
'f rigura 5.1 shows the preconstruction floodplain including th
>%i alat:d features that would be within its limits.
e various plant-y
{;
\\
NP-3 OES 5-3
'-