ML20079N296
| ML20079N296 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 10/31/1975 |
| From: | Marcy B, Morgan P, Owen B NUS CORP. |
| To: | |
| References | |
| RTR-NUREG-1437 AR, NUDOCS 9111110147 | |
| Download: ML20079N296 (18) | |
Text
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MONTICELLO NUCLEAR GEN PLANT l'
ATTACliMENT 5
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k EFFECTS OF A HEATED DISCHARGE h
CN THE ECOLOGY OF THE
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316(a) Type I Demonstration on the Monticello Nuclear Generating Plant, d
Monticello, Minnesota I
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PREPARED FOR NORTHERN STATES POWER COMPANY
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PREPARED BY L:
M. Af::al
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B. R.
Oblad i
B. B. Owen F.
P. Richards 7
G.
C.
Slawson
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ECOLOGICAL SC3'NCES DIVISION NUS CORPORATION i
1910 COCHRAN ROAD b
PITTSBURGH, PENNSYLVANIA 15220
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CLIENT NO. 6531 1
OCTOBER 1975.
s D BY: _
d BnADFOpr ~B. OWEN JR.S Ph.D.
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PRCJEu MANAGER g[
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PAUL V. MORGAN ~
BARTON C. MARCY,'JR.
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VICE PPISIDENT AND MANAGER - AQUATIC MJ GENERAL MANAGER ECOSYSTEMS DEPARTMENT ECOLOGICAL SCIENCES
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DIVISION 1
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MONTICELLO NUCLEAR GEN PLANT ATTACilMENT 5 4
4 TABLE OF CONTENTS IAH "&
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SUMMARY
AND CONCLUSIONS - 316(a) TYPE I DEMONSTRATION FO' THE MONTICELLO NUCLEAR GENERATING 7~.Al'~
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2 316 (a) TYPE I DEMONSTRATION FOR THE MONTICELLO NUCLEAR GENERATING PLANT I
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ENGINEERING AND HYDROLOGIC DATA.
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3.1 PRIMARY PRODUCERS.
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-CONCLUSIONS 14 H
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nngoDUCTION gonowing summary and conclusions are based on the extensive s'. cal, chemical and ecological studies conducted at the Monti-n Site from 1968-1974.
Rather than cite each study in the sum-
', pages of the main text of the 316(a) Type 1 demonstration are ferenced, should more detailed information be desired.
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TGINEERING AND HYDROLOGIC DATA u
nticello Nuclear Generating Plant is a base load facility 7_
a design generating capacity of 545 MWe. The cooling system E[eMonticelloPlantisconstructedtooperateinopencycle, d,er cycle, partial recirculation and closed cycle modes.
Nor-m n[theopencyclemodeisusedduringperiodswhentheambient temperature is less than 68"F (20'C) and the helper cycle mode dsed when temperatures exceed 68'F (20*C).
The plant is operated d$sentia11y full capacity at all times.
Significant variability in
-t(rejectionratesoccuronlyduringshut-downandstart-upperiods.
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-armal plume mapping surveys have been conducted 34 times during
-- 1971-1973 period.
Of these, eight surveys have been selected
-Zdefine variations in plume configuration under various seasonal, o
j-Qdrologic and plant (cooling system) operating conditions.
Com-
'ljance with applicable regulations was evaluated using the draf t MbSpermitrestrictionsandMinnesotawaterqualitystandards.
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-yerdiacharge and cooling system mode are the major factors in-s9encing the spatial extent of the thermal plume generated by the bicelloPlant.
Under extreme summer low flow conditions, non-
% 11ance with the draft NPDES permit requirements and state water iuklity standards is indicated both with and withcut the use of ling towers.
With high f.'
is, compliance with state water
'?ality standards is achieved both with and without cooling towers, s
ever, non-compliance with the draft NPDES permit is indicated.
nder " normal" summer operations (near median river discharge
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compliance with t$ cooling towers operated in the helper mode),
tandards may be indicated.
Occasional non-compliance with 6andards.is indicated for winter and seasonal tranaition
- .In some cases, non-compliance with the restrictions of T.
ft NPDES Permit is possible without violation of the state
- lity standards.
L.
!f thermal survey results and historical discharge data 1d that during 70 percent of whe period from June through r, the immediate discharge zone (the +90*F (+5'C] isotherm) n.-
ed over less than half of the river width and 'less than t
't below the plant outf all.
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'c-s uality (other than temperature) in the Mississippi River is ih:
preciably affected by the operation of the Monticello Plant.
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3.
ECOLOGICAL DATA s
3.1 PRIMARY PRODUC2RS Periphyton, phytoplankton and macrophyton are the three potential l.
sources of primary production in the Mississippi River at the Mon-ticello Site.
Phytoplankton was not extensively investigated at I
the site but is assumed to have a minor role in river trophics as compared to periphyton.
l Phytoplankton at the Monticello Site is dominated all year by dia-toms (see p. 69), although green and blue-green algae become im-portant in summer.
Moyle (1940) indicated that blue-greens domi-l nated some of the summer communities of the upper Mississippi River during his studies (see p. 70).
I Periphyton was studied extensively at the Monticello Site.
Studies were based on the algae that colonized artificial substrates.
From 1968 through 1974, 134 taxa of algae were identified, the majority of which were diatoms.
Spring periphyton was dominated by diatoms, mainly Gomphonema olivaceum, Diatoma vulgare, Synedra ulna and Navicula gracilis.
Peak production occurred in the summer when both diatoms and d
plue greens were abundant.
Chroccoccus minimus was the major ummer alga.
Diatoms dominated in the fall when species of Soceaneis were 7ery common.
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$l Species composition of periphyton communities did not differ signi-0; ficantly between the intermediate discharge zone and the " ambient D.
zone" (see p. 73 ).
However, within the immediate discharge bk l
- one there was a shift in species dominance.
Stigeoclonium nanum, Characium pringsheimii and Achnanthes exigua were more abundant in the immediate discharge than in other zones (see p. 73).
1 Species diversity was greatest in the immediate discharge in the spring (see p. 75) but no trends were discernible during other seasons.
Similarly, chlorophyll a-and total algae densities failed to show major differences among areas.
The cumulative effects of the Monticello Plant discharges do no't affect the overall balance of the periphyton communities of this region of the Mississippi River.
Few data exist on the macrophyton of the Mississippi River in the Monticello Plant area.
Major taxa present include Fontinalis anti-Pyretica, two Potamogeton species and Cladophora glomerata.
'These
. plants are assumed to play a minor role in river trophics as com-pared to periphyton.
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$ 3.2 ' ZOOPLANKTON n
Zooplankton of the Monticello Site has not been investigated recent-ly.
Past studies show that few crustaceans inhabit the region.
However, protozoans and rotifers may be common in the area (see p.
103). The trophic importance of zooplankton is considered to be limited in this portion of the Mississippi due to the small 5
6 number of organisms that feed on zooplankton and due to the paucity of crustaceans in the zooplankton communities.
3.3 MACROIINERTEBRATES Macroinvertebrate studies were initiated on a five-mile stretch of the Mississippi River in 1968 to gather baseline information before the construction of the Monticello Plant.
Preoperational data in-clude the results of investigations from the summer of 1968 to the end of 1970.
Operational information has been collected since the plant start-up in 1971.
4 Two major types of habitat have been described from the survey area.
In one habitat type, the backwater arecs and protected shoreline areas where grasses and sedges grow, the water in usually less than two feet deep and the substrate is silt and mud.
Current velocity in this habitat may fluctuate greatly j
throughout the year.
Random qualitative collections were made 3
,along the shorelines and backwaters with invertebrate sweeping nets.
In this habitat, the diverse fauna consisted of 11 orders, 32 fam-ilies and 66 genera (sea p. 169 ).
Coleoptera, Ephemeroptera and Hemiptera were the dominant orders.
L The main channel represents the other major type of habitat.
Sub-strates are primarily gravel, rubble and boulders with some sand, gurrent velocity is substantial but fairly consistent.
Quali -
tative analysis of four artificial substrate samplers placed in the central channel during 1968 produced representives of eight 6
~ orders, 15 families, and 25 genera (see p. 167).
Caddisflies and were the major components of the benthic fauna in the mayflies main channel, although five genera of stoneflies were also repre-
- senteo, Presence of these three orders is indicative of good water quality in this part of the Mississippi River.
In an extensive quantitative program from 1969 through 1972,
' concrete blocks (artificial substrates) were placed at two control stations above the intake and at six experimental stations below the proposed discharge (see p. 136).
In operational years (1971 and 1972), 9 stations were in the outer discharge zones, I
.although 3 of these were, at times, at ambient temperatures, a
. and 4 stations wer in the intermediate discharge zone.
None of the stations were in the immediate discharge zone.
Although major taxa composition remained the same (see pp.169 to 175) in all stations, the percent contribution of dominant groups changed during operational years with a substantial percentage increase of caddisflies, particularly in 1972 (see p. 176).
A recolonization study in 1973 monitored one control station d one experimental station between July 1971 and July 1972 (see
- p. 142-158).. The experimental station was in the defined outer ischarge zone, although over 50 percent of the time it fell ithin the +3 F
(+ 2
- C ) isotherm (see p. 179).
Caddisfly larvae eached higher population levels in the experimental station, bhile mayfly and dipteran numbers were reduced (see p. 181).
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This increase of caddisflies was statistically significant in three of the eight sampling cycles (see p. 182).
While increases and decreases in major tsxa occurred in the thermal discharge zone, none of the major taxa were excluded.
In 1972, maximum standing crop was reached one month earlier in the experimental station than in the control station, probably due to the constant elevated temperatures at the experimental station.
Macroinvertebrate growth rates showed no significant differences between the heated water and control stations.
In a drift study, the experimental station was located in the intermediate discharge zone (see p. 140).
Drift compositions at the experimental and control stations were
-i not significan+.ly different at the order level nor was the relative magnitude of the major taxa within each order significantly different.
Elevated temperatures in the intermediate discharge zone (see p. 184) produced no measurable change in drift density as ccmpared to the control station.
The adult light trap study provided a species list of the major taxa near the Monticello site.
There did not appear to be a significant change in the emergence periods of the I
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ly 1 major taxa, with the possible exception of Macronemum zebratum.
Macronemum zebratum emerged two weeks earlier at 5 the light trap near the thermal plume area than it did at the control light trap above the intake.
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l 3.4 FISH Various sampling gear and analytical methods were employed to examine the impact of the Monticello Plant,on the balanced,
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- indigenous fish populations of the Mississippi River.
Sampling techniques included electrofishing, seining, trap nets, creel census and tagging (see pp. 189-192).
Catch data were i
transformed to catch-per-unit-effort (catch per alectro-fishing-hour, catch per trap net set, catch per seine haal).
Spawning sites and time of spawning were determined by examination of fish condition (state of maturity and condition f acto::s).
- i. Carp and shorthead redhorse were the most abundant species
' captured during pre-operational studies.
Game fish were
- restricted to microhabitats within each sector, which limited
.their overall anundance (see p. 214).
After the plant went into operation, fish were found in the immediate discharge area regardless of whether or not the a
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plant was generating.
Rough fish species continued to dominate the catch in all areas (see p.
197), a reflection of the relative abundance seen during pre-operational studies.
In 1973, rough fish were most abundant in the outer discharge The intermediate discharge area yielded greater area.
catches than the immediate discharge area (see pp. 237, 255, 263).
In 1974, rough fish wero still least abundant in L
the immediate discharge area but were more abundant in the intermediate discharge area as compared to the outer discharge r area, at least through June (see pp. 245, 259, 267).
Game species were caught most frequently in the Lemediate discharge area in 1973; distribution was about even in the other areas (see pp. 239, 257, 265).
In 1974, game fish were abundant in the intermediate discharge (see p. 261).
In all cases, the catch of game fish wan much lower than that of rough fish.
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.. Seining studies were conducted both before and after plant Operation.
Stations in the adjacent water body segment and
'the intermediate discharge area were compared by rank e
correlation (see p. 203).
The results indicated that species composition changes were minor.
The Lamediate and outer discharge areas were not sampled in both years, therefore, no comparison cou7d be made.
Seining studies 10 t
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'e f of young-of-the-year smallmouth bass and white sucker indicated i that differences in abundance between the intermediate h discharge area and ambient control sta' ions were not c
statistically nignificant (see p. 704).
It was speculated
$ that there may have been some inhibitory action on spawning
'[ and/or egg incubation in the intermediate discharge area
) but that heat could not be singled out as the causative 3
( agent.
Growth of young-of-the-year smallmouth bass and white suckers was significantly f aster in the heated water (see pp. 204, 216).
f Spawning studies were conducted for the dominant species in
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the area:
shorthead redhorse, silver redhorse, white sucker S
and carp (see p. 204).
Since the plant was down during most
- of the spawning periods of white sucker, shorthead redhorse and silver redhorse, anticipated impact must be inferred
?[ from the existing data.
Carp preferred flooded areas off 2
the main river, so the plant is not anticipated to have any impact on their spawning success.
Spawning beds of Y
other species were located in many areas around the plant
[
site (see p. 271).
Some of these beds are expected to be I in the hea'ted effluent.
The impact is anticipated to be
- f minimal because most spawning takes place in the spring and
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early summer when flows are high and heat should be rapidly y
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dissipated.
Also, most spawning areas likely to be in the heated effluent are in the intermediate discharge area, further reducing heat levels.
Yellow perch and walleye overwintering in the discharge canal are expected to experience reduced spawning success (see p. 219).
4 A small sport fisherv was found to exist in the immediate discharge area in the fall.
High catches of smallmouth bass and walleye were noted (see p. 210).
The occurrence of these fish in the fall is expected to establish a new i
fishery in the Monticello area for highly desired game t
l species.
A creel census of other areas near the plant indicated that a rather unsophistic' ted and under-utilized fishery existed.
l Fish were attracted to the immediate discharge area during the winter months.
The standing crop of fish in this area did not appear to be in excess of the carrying capacity as l
- condition factors of these overwintering fish are comparable to published data for the species (see p. 340).
Winter shutdowns are expected to result in fish kills due to cold l -
shock.
Winter cold shock mortality has not adversely I
affected fish populations in the river, based on catch-per-unit-effort data.
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k The major conponents of the balanced, indigenous population of fish inhabiting the area of the power plant have been fminimallyaffectedbyplantoperation.
Rough fish dominated
' the catches of large species in operational years as in pre-operational years.
Forage fish species composition was I virtually unaffected.
Fish frequenting the immediate
' discharge area included:
smallmouth bass, black crappie, walleye, northern pike, carp, shorthead redhorse, silver
, redhorse and white sucker.
Spawning of some species is expected t.o be ir.hibited by the heated discharge, but I, rapid dissipation of prohibitively high temperature water 0 is expected to minimi::e i;apact.
Fish kills are probable during the winter, however, the low standing crop in the timmediate discharge area is expected to reduce impact.
A potential sport fishery in the dischargo canal is anticipated.
In summary, the balanced, indigenous population of fish at
'he Monticello Site is expected to be maintained with a t
minimum of impact.
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cotJCLUSIONS_
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~1though there have been periods of non-compliance with thermal hgu3ations (both state and NPDES permit), there is no ir.dication f prior appreciable harm to the biota of the Mississippi River I thin the area of influence of the Monticello Nuclear Generating
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ant.
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Water (Juality parameters measured (other than temperature) were
}r.otaffectedbythssperationoftheMonticelloPlant.
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e' Primary producers displayed some shifts in periphyton species
" composition in the 3 xnediate discharge while maintaining a balanced ommunity.
Intermediat? and outer dischar:e area i kziphyt mmmunition were indistinguisable from those of the control ares..
Macroinvertebrates were dominated 5y caddisflies and the 4
benthos standing crop maximum was one month earlier in the area incnediately dow. stream from the discharge.
Corwunity stability was not measurably affected in discharge zones.
Fish populations have not been noticeably altered in composition in the affected arcas since the Monticello Plant started opera"
[ tion.
Rough fish predominate but game fish are, at times, abund-ant in the immediate discharge.
Minimal impact on spawning of I local fishes is predicted.
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evidence presented in this demonstration indicates that the The operation of the Monticello Nuclear Genereting Plant has not pro-uced appreciable harm and has not Jnterfered with the maintenance f balanced indigenous populations at all trophic levels.
Thus ny effluent limitations would be "more stringent than necessary o assure the protection ar.d propagation of a balanced indigenous pulation of shellfish, fish and wildlife" in the Mississippi niver.
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