ML20140F228
| ML20140F228 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 12/31/1996 |
| From: | NORTHEAST UTILITIES SERVICE CO. |
| To: | |
| Shared Package | |
| ML20140F232 | List: |
| References | |
| NUDOCS 9705020176 | |
| Download: ML20140F228 (14) | |
Text
..,
f Annual Environmental Protection Plan Operating Report January 1 - December 31,1996 Millstone Unit 3 Environmental Protection Plan prepared by Northeast Utilities Service Company P.O. Box 270 Ilartford, Connecticut 06141-0270
. April 1997 9705020176 970428 PDR ADOCK 05000423 R
ppy
f Annual Environmental Protection Plan Report - 1996 i
1.
Introduction This report covers the period January 1 - December 21,1996. Unit 3 was placed on the NRC Watch List on January 29, and has been off-line since March 30, Ibliowing the declared inoperability of the auxiliary feedwater containment isolation valves. Since then, Unit 3 has been working to verify corrective actions and to demonstrate readiness for startup. During 1996, Unit 3 operated at an annual capacity factor of 25%.
As required by the Millstone Unit 3 EPP, this Annual Environmental Protection Plan i
Operating Report (AEPPOR) includes:
1) summaries and analyses of the results of environmental protection activities, 2) a list of EPP noncompliances, 3) a list of all changes in station design or operation which involved a potentially significant unreviewed environmental question, and 4) a list of non-routine reports, describing events that could result in significant environmental impact.
2.
Environmental Protection Activities 2.1 Annual National Pollutant Discharge Elimination System (NPDES) Report of Ecological Monitoring (EPP Section 4.2)
Paragraph 5 of the referenced NPDES permit requires continuation of biological studies of MNPS supplying and receiving waters, entrainment studies, and intake impingement monitoring. These studies include analyses of intertidal and subtidal benthic communities, finfish communities, entrained plankton, lobster populations, and winter flounder popul.ition3. Paragraph 13 of the permit requires an annual report of these studies to the Commissioner of Environmental Protection. The report that fulfills these requirements for 1996, Monitoring the Marine Environment of I.ong Island Sound at Millstone Nuclear Power Station. Waterford. Connecticut - Annual Renort.
B96, presents results from studies performed during 3-unit operation, and compares them to those from 2-unit operation. Past reports have indicated that the added cooling water flow for Unit 3 affects impingement and entrainment, causes sediment scouring near the Millstone Nuclear Power Station (MNPS) discharges, and alters the characteristics of thermal effluent plume. The extended shutdown of MNPS in 1996 has also caused some changes to the physical environment in the vicinity of the station discharge. The biological effects of these changes are summarized in the Executive Summary section of the above-named report (Attachment 1) and further discussed in the report itself(Attachment 2).
1996 AEPPOR 1
t 2.2 Effluent Water Quality Monitoring 1
Paragraph 6 of the referenced NPDES permit requires monitoring and recording of many water quality parameters at MNPS intakes and at 37 monitoring points within the plant, including outfalls of each unit to the effluent quarry, and outfall of the quarry to Long Island Sound. Paragraph 11 of the permit requires a monthly report of this monitoring to the Commissioner of Environmental Protection. The report that fulfills these requirements, Monthly Discharge Monitoring Renort (DMR), includes data from all three Millstone units. Those data that pertain to Unit 3 are summarized in Table Ia.
During 1996, twenty NPDES pennit exceedances (i.e., events where the value of a parameter was beyond the permitted limit) or exceptions (i.e., events where a permit condition was not met) were reported (Table Ib). Several discharges occurred when maintenance activities necessitated alterations of certain system and piping configurations.
Specifically, seven of these events involved the discharge of a j
wastewater stream through an alternate discharge point, even though the water quality was within pennit limits. A protocol has been established with the CT Department of Environmental Protection regarding the reporting of such events, including prompt telephone notification, followed by written notification. The remaining thirteen DMR non-routine events are summarized chronologically below:
failure to analyze a surfactant sample from DSN 001C in January g blizzard e
precluded timely transport to the laboratory);
discharge in April from the Condensate Polishing Waste Neutralization Tank (DSN e
001C-6), which occurred without two operating circulating water pumps (upon further review, this event appears not to represent a reportable exception, as the NPDES permit does not require dilution flow for this discharge);
two discharges from DSN 001C-6 in May, which occurred without proper e
sampling or analysis; discovery ofion exchange resin beads in the discharge from DSN 001C in May and e
June (these were identified as having passed through an inline filter; the filter was replaced and the Condensate Polishing Facility sump was cleaned);
a release on June 2 of approximately 584 gallons of 12.5% sodium hypochlorite e
solution through DSN 001C-5 (Service Water). This release was caused by an improper valve lineup that allowed the solution to siphon from the storage tank; although the release was not analytically measured, it was calculated that this event would have caused a permit limit for free available chlorine (FAC) to be exceeded; in July, a vendor performing landscaping activities onsite spilled approximately 10 e
gallons of herbicide. Most was immediately cleaned up, but approximately 2 gallons of diluted product reached a yard drain discharging via DSN 006, before the spill was contained; in August, a fitting on the Unit 3 cmergency diesel generator cooling waterjacket e
came loose, and 30-50 gallons of cooling water was discharged to a floor drain, 1996 AEPPOR 2
t then to DSN 006. Ahhough this discharge was unplanned, diesel generator cooling water discharge is a pemaitted input to DSN 006, and sampling at the time of discharge showed water quality to be within permit limits; on September 4, FAC at DSN 001C-5 was measured at 0.30 mg/L (permit limit O.25 mg/L); this was the result of reduced water flow to the hypochlorite injection system without a reduction in injection pump stroke; on October 31, the Condensate Polishing Waste Neutralization Tank was discharged, as permitted, through DSN 001C-6. During this discharge, the N line pil monitor indicated a pil of 9.4 (permit limit 9.0); the discharge was immediately terminated, and the tank was reprocessed. The final pli of the tank was 6.6; finally, two NPDES permit incidents involved pli monitors, either beyond the e
calibration schedule (October at DSN 001C-6) or out of service, requiring manual grab samples every 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, one of which was taken 45 minutes late (December at DSN 001C).
In each case, notification was made to the appropriate agencies via telephone, letter, and DMR.
(
3.
Environmental Protection Plan Noncompliances i
During 1996, no EPP noncompliances were identified for Unit 3.
4.
Environmentally Significant Changes to Station Design or Operation During 1996, no Unit 3 Plant Design Change Records (PDCRs) met the acceptance criteria for inclusion in this report, i.e., a) were initiated during the report year, and b) included a determination that an unreviewed environmental impact could occur.
As of December 31,1996, Unit 3 has 195 System Operating Procedures; of these,66 were added or revised during 1996. In addition, many procedures were modified to reflect small changes, ofinsuflicient magnitude to require the ssuance of a new revision. Ilowever, each of these changes, as part of the review / approval pmcess, included an environmental evaluation; none was determined to have involved an unreviewed environmental impact. Additionally, a review of design and system changes that had been initiated in previous years, but had an Environmental Review performed in 1996, indicated that none constituted an unreviewed environmental issue, per the EPP criteria.
5.
Non-Routine Reports of Environmentally Significant Events During 1996, no events occurred at Unit 3 that met the acceptance criteria for inclusion in this report, i.e., required submittal of a Licensee Event Report (LER) from Unit 3, and involved a situation that could result in a significant environmental impact. Of the 51 events that constituted reportable occurrences in 1996, none were determined to cause a significant environmental impact.
1996 AEPPOR 3
Table 1. Millstone Unit 3 NPDES Data Summary, Jan.1 - Dec. 31,1996.
a). Selected water quality parameters for Unit 3* (any exceedances are in bold type).
max discharge discharge discharge discharge avg max max SWS flow range pli range temp. range temp. (avg) AT FAC TRC FAC l
3 (10 gpm)
( F)
( F)
( F)
(ppm)
(ppm)
(ppm) 1 l
Jan.
638-942 7.8-8.1 50.9-63.7 56.3 18.9 0.14
<0.02 0.17 Feb.
790-948 7.7-8.0 46.6-57.7 52.4 17.7 0.15
<0.02 0.17 Mar.
790-948 7.7-8.2 39.2-61.2 53.5 16.9 0.09 0.04 0.17 Apr.30-790 7.3-8.1 38.3-47.8 42.4 0.7 0.12 0.04 0.16 May 30-633 7.7-8.2 44.4-55.6 50.1 0.4 0.13 0.04 0.18 June 30-633 7.7-8.1 52.2-63.5 58.2 0.2 0.09 0.07 0.16
- July 30-790 7.6-8.3 61.7-67.8 65.2 0.2 0.07 0.03 0.18 Aug.30-948 7.7-8.1 63.7-79.9 68.0 0.8 0.10 0.06 0.21 Sep.15-942 7.8-8.1 64.0-71.1 68.0 1.1 0.14 0.03 0.30 Oct.15-790 7.8-8.1 57.2-67.1 61.0 0.2 0.09 0.03 0.20 Nov.30-334 7.8-8.0 48.5-58.5 53.2 0.0 nd*
<0.02 0.19 Dec.30-942 7.8-8.2 43.7-50.5 46.9 2.0 0.10
<0.02 0.18 b). Number of NPDES exceedances or exceptions during year *.
Susp.
Ikiric oil &
pH temp.
BOD COD hydrazine acid conduct. hthium grease metals other 3
0 2
0 0
0 0
0 0
0 0
0 0
15 Notos:
- Parameters are measured at Unit 3 discharge (DSN 001C), except for TRC, which is measured at MNPS discharge (quarry cuts; DSN 001) and SWS FAC (service water system; DSN 001C-5).
- Although the highest FAC measured was 0.16 ppm, a sodium hypochlorite leak is believed to have caused an exceedanec; see text for additional details.
- Circulating water was not chlorinated during this period, FAC was not measured.
- Some parameters are measured at more than one point within Unit 3 or only under certain operating conditions.
Values represen; number of NPDES exceedances or exceptions for all discharge points; see text for additional details.
1996 AEPPOR 4
1 I
ATTACilMENT 1 to the Millstone Unit 3 Environmental Protection Plan Annual Environmental Protection Plan Operating Report January 1 - December 31,1996
1 1
?
Executive Summary The bay anchovy is typically the most abundant Fish Ecology Studies ichthyoplankton species collected in estuaries within its range and was the dominant larval taxon entrained Studies of fish assemblages in the vicinity of at MNPS. Recent abundance has been relatively low MNPS were conducted to determine the effects of in comparison to the mid-1980s, but this decline station operation. These effects have been defined as occurred prior to three-unit operation and no station-related changes in the occurrence, distribution, significant trends were found for either two-or three-and abundance of fishes, which can alter community unit operation. The egg and larval densities and the structure. Potential efTects include the entrainment of entrainment estimate for 1995 were among the lowest early life history stages through the cooling-water of the past 20 years. The numbers of eggs and larvae system (probably the most important effect), impinge-entrained each year were not significantly correlated ment ofjuvenile and adult fish on the intake screens, with densities found the following year, implying no which was mitigated by the installation of fish retum direct effect of MNPS on the spawning stock of this sluiceways at Units I and 3, and changes in distribu-shon-lived species.
tion in Jordan Cove as a result of the thermal Atlantic and inland silversides are among the discharge, most common shore-zone species along the Trawl, seine, and ichthyoplankton (fish eggs and Connecticut coast. These species fluctuate m relative larvae) monitoring programs were established in 1976 abundance from year to year. Typical of short-lived to provide information for the assessment of impacts species, the abundance of silversides is highly variable i
from MNPS operation. These programs provided the and annual catches by trawl and seine have ranged l
basis fbr identifying taxa potentially affected, as well over two orders of magnitude. Recent catches of as information on long-term abundance trends used to silversides by trawl and inland silverside by seine were measure changes in the local populations. About 130 within historic ranges.
However, the Atlantic l
ditTerent fish taxa have been collected in these silverside has significantly decreased in abundance monitoring programs. Of these, six taxa, including during the three-unit operational period at the Jordan American sand lance, anchovies, silversides, grubby, Cove seine site. This decrease was probably not cunner, and tautog, were identified as having the related to thermal effects, as only a minimal (0.8"C) potential to be impacted by MNPS, either by increase in water temperature is found at the seine entrainment or exposure to elevated water tempera-station, which is less than typical summer diurnal tures from the plant discharge. Abundance data were variation on the shallow sand flats. Because catches of analyzed separately for the two-unit 0976-85) and adults by trawl during winter did not show similar three-unit (1986 through 1995 or 1996, depending changes in abundance, MNPS likely has not affected upon the sampling program) operational periods and the local Atlantic silverside population for the entire 20-year data series (both periods The grubby is unique because unlike other combined) to detennine if changes in abundance have potentially impacted species it experiences no fishing occurred.
pressure and has little forage value. Both larval and American sand lance larvae ranked third among adult grubby abundance indices have been relatively entrained fish larvae and densities in entrainment stable throughout the 20 years of monitoring, samples have decreased after per. king in the late 1970s suggesting little plant effect.
and early 1980s. Declines in sand lance abundance The most abundant of the fish eggs entrained were also apparent in other areas of the Northwest were cunner eggs, which accounted for more than 50%
Atlantic Ocean, with abundance found to be inversely of all eggs collected since 1979. During three-unit correlated with that of Atlantic herring and Atlantic operation, cunner eggs increased in abundance, with mackerel, both of which prey upon larval sand lance.
the density of cunner eggs in 1995 the third largest flowever, abundance has increased again in recent recorded, as was the annual entrainment estimate.
years, although the mean larval density during 1995 However, the densities of larvae Ibund decreased by was the lowest of the past 4 years. Given the large about 50% from 1994. Young-of-the-year cunner changes in abundance of this fish along the Atlantic accounted for a higher proportion (about 70%) of fish coast, effects of MNPS on sand lance abundance is caught by trawl since three-unit operation began.
ditTicult to ascertain, but is probably small.
Trawl catch at a station near the MNPS intakes showed
Q a significant decline during two-unit operation. This during the three-unit operational period. Therefore, decrease was most likely related to the mid-1983 changes in the relative proportion of juveniles and removal of a rock cofferdam at the Unit 3 intake adults were probably unrelated to entrainment losses.
structure that provided habitat for cunner. Afterwards, in addition, the decline in juvenile and adult tautog catches became similar to another station in nearby abundance in Long Island Sound that began in the mid-Niantic Bay. The entrainment of eggs is the mid-1980s coincided with the decreasing numbers of greatest potential impact of MNPS on the cunner eggs collected at MNPS. If the decrease in adult population.
Ilowever, if egg losses affected numbers was caused by entrainment losses, then the recruitment, then juvenile abundance should decrease reduction in egg abundance should have lagged the in relation to older fish. This decrease was not decline ofjuveniles by several years because females apparent in the length-frequency distributions, and do not mature until age-3 or 4. Therefore, the lower relative abundance of juveniles actually increased abundance of tautog eggs was probably due a decline during the three-unit operational period.
in the abundance of spawning adults from fishing The tautog was the second-most abundant egg rather than the operation of MNPS. At present, taxon entrained, accounting for over 27% of the total tautog stocks are considered overfished and because eggs collected since 1979, with mean density in 1995 of the long life and slow growth of this species, the largest seen since 1990. Tautog larvae, however, abundance should remain depressed until fishing were not as prominent, ranking eighth in abundance, modality rates are substantially reduced.
No correlation was found between eggs and larvae and no significant trends in abundance were found during Winter Flounder Studies either operational period. Catches of tautog by trawl were dominated by young-of-the-year. In contrast to The local Niantic River population of winter 1994-95, when total trawl catch was the lowest in 20 flounder (Meuronectes americamss) is potentially years, the catch during 1995-96 was the largest.
affected by t'1e operation of MNPS, particularly by Tautog, particularly fish in size-classes that correspond entrainment of larvae through the cooling-water to ages-3 through 5, were also taken in lobster pots.
systems of the three operating units. As a result, The 1996 catch at the Jordan Cove station was six extensive studies of the life history and population times the previous high. The reasons for this increase dynamics of this valuable sport and commercial are unclear, but may have been related to changes in species have been undertaken since 1976.
prey availability.
In contrast to the previous 2 years (1994-95),
Special studies on tautog eggs showed that when monthly mean seawater temperatures were large (65-80%) decreases in egg abundance occur warmer than average, temperatures recorded at the following early evening spawning through the MNPS intakes during 1996 were among the coolest following morning, most probably a result of high of the past 21 years, particularly during spring and natural mortality.
Pelagic tautog eggs disperse summer, The cold wcather produced heavy ice cover rapidly from spawnine sites by tidal transport and in the Niantic River, dlaying the start of the adult densities in nearshore areas are relatively uniform.
winter flounder survey until February 27. The D-Based on hydrodynamics, a comervative measure of mean trawl catch-per-unit-efTort (CPUE) of fish the source area for eggs entrained at MNPS includes larger than 15 cm during the spawning season was a radius of a~oout 5 nautical miles. Two daily 1.6, the lowest of the series. Larger females have estimates of the instantaneous standing stock of made up a greater proportion of the spawning stock tautog eggs within this area equaled or exceeded in recent years as abundance declined to low levels.
annual entrainment estimates at MNPS and, in fact, The Jolly stochastic model was applied to mark and would have been even larger if high egg mortality recapture data to estimate the absolute abundance of rates had been taken into account. This implies that the adult spawning population.
The abundance MNPS entrainment effects may be relatively small.
estimate for 1995 was 5,574 winter flounder, lower if egg losses due to entrainment affected than the estimates of about 10-16 thousand for 1992-recruitment of tautog, then juvenile abundance 94 and considerably less than estimated population should also decrease and the relative abundance of sizes during 1984-91 that ranged between 33 and 80 older fish would appear to increase in the short term, thousand spawners. One-third to almost two-thirds Based on length-frequency distribution from trawl of the winter flounder found in the Niantic River catches, the percentage of juvenile tautog increased during the spawning period each year were mature
i l
j females.
Female spawner abundance estimates abundance was unexpected, given the relatively high j
ranged from 2,427 (1996) to 68,899 (1982), with numbers of young produced in the 1995 year-class.
{
corresponding total egg production from about 2.1 to This abundance index was signincantly correlated j
39.9 billion each year, with that of young Osh taken in the Niantic River The low abundance of newly-hatched larvae in during 1994, and also indicated that the 1988 and Niantic Bay compared to the Niantic River suggested 1992 year-classes were relatively abundant, whereas that most local spawning occurred within the river.
the 1993 year-class was weak. Few juveniles have In addition, abundance indices of Stage I larvae in been taken within the Niantic River during the adult the river were signincantly correlated with spawning population surveys in recent years.
j independent estimates of female spawner egg Young-of-the-year abundance indices were either not production. Densities of Stage 1 and 2 !arvac in the correlated or were negatively correlated with the j
Niantic River during 1996 were about average, abundances of age-3,4, and 5 female adult spawners.
except for Stage 2 larvae at a station in the upper Thus, none of the early life stages was a reliable j
river, which was the second highest of the series.
index of year-class strength for Niantic River winter llowever, abundances of Stage 3 and 4 larvae thic Dounder stock.
{
}
year were at or below average at all statio.:. Since Egg production estimates from annual spawnmg 1976, annual larval abundances i: Niantic Bay surveys were scaled to numbers of spawning females appeared to reDect region-wide tr.mds as they were and used as recruitment indices. These indices highly correlated with abundance indices for Mount together with adult female spawning stock estimates llope Bay, MA and RI.
and mean annual February water temperatures were Smaller size-classes of larvae were dominant in used to fit a three-parameter Ricker stock-recruitment the river and larger size-classes were more prevalent relationship (SRR). Additionally, an indirect esti-in the bay. The reduced cooling-water How in 1996 mate of the winter Counder theoretical rate of resulted in larger catches of smaller larvae in MNPS increase (the SRR a parameter) was used for entrainment samples, which could have been the modeling winter Counder population dynamics for result of reduced net extrusion under low How and impact assessment. The value of a in biomass units slower water velocity conditions, was estimated as 5.87. The estimate of b (the second in Niantic Bay, growth and development were SRR parameter), which describes the annual rate of correlated with water temperature. In the river, compensatory mortality as a funct on of stock size, i
growth appeared to be related to both water has shown little annual variation since 1988. The temperature (positively) and larval density third parameter in the SRR described a negative (negatively). Growth and development were slower relationship between winter Counder recruitment and than average in 1996, likely due to cooler water w;.ter temperatures in February, the month when temperatures. Estimated mortality of larvae in the most spawning, egg incubation, and hatching occur.
Niantic River for 1984 95 ranged from about 82 to The number of larvae entrained through the 98% and was 94.8% in 1996. Density-dependence condenser cooling-water system at MNPS is the most was examined using a function comparing mortality direct measure of potential impact on winter with egg production estimates (a measure of early Dounder. Annual estimates of entrainment were stage larval abundance) and various monthly and related to both larval densities in Niantic Bay and seasonal water temperatures.
The best model plant operation. The entrainment estimate in 1996 indicated that larval mortality increased as egg was 53.9 million larvae, the second lowest since production increased and spring (Apil-June) water three-unit operation began in 1986. This was largely temperatures decreased, attributed to plant operation as cooling-water volume Densities of newly metamorphosed demersal during 1996 was the lowest in the threeanit young were relatively low in 1996. Young winter operational period, with Units 1 and 2 shut down for Hounder were perticularly scarce during late summer all and Unit 3 for most of the larval winter flounder and the median beam trawl CPUEs were among the season. The decrease in cooling water use resulted in lowest recorded since this sampling began in 1983.
a calculated reduction in entrainment of about 72%
The D-mean CPUE calculated for young winter (138 million larvae) from that expected if all three Counder taken during the late fall and early winter at units had operated fully during the season.
the trawl monitoring program stations was 4.8 in The impact of larval entrainment on the Niantic 1995-96, the lowes: value since 1976-77. This low River stock depends upon the fraction of the winter
s 5
flounder production entrained each year. Empirical years aller the scheduled termination of Unit 3 mass-balance calculationt for 1984-96 showed that a operation in 2025, and became virtually identical to large number of entrained larvae come from areas of the baseline in 2033.
Long Island Sound other than the Niantic River. In he probabilities that the Niantic River femle previous years, an estimated 14 to 38% of entrained spawning stock biomass would fall below selected larvae originated from the Niantic River, but the reference sizes (25, 30, and 40% of MSP) were estimate for 1996 was 59%. On the other hand, the determined to he!p assess the long-term effects of fraction of the annual river production entrained, MNPS operation. A stock smaller than 25% of MSP which has ranged from 5.4 to 42.3% in previous is considered overfished, whereas one that is at 40%
years, was a moderate 25.7% in 1996.
of MSP can maximize yield to the fisheries while A stochastic compuer simulation model remaining stable. For both baseline and MNPS-(SPDM) was use<l for long-term assessments of impact simulations, stocks were likely (p = 0.92)
MNPS impact over a 100-year period (1960-2060).
greater than 40% of MSP in 1970. At the lowest i
The winter flounder stock simulated was female point of both stock projections in the mid-1990s, all spawner biomass (Ibs), which is more directly related replicates of the stocl! projections were less than 25%
s to reproductive potential than fish numbers.
of MSP. Simulated reductions in fishing allowed for Conditional mortality rates corresponding to larval a rapid increase in spawner biomass in 2000. By entrainment from mass-balance calculations and 2010, spawner biomass of the impacted stock was juvenile and adult impingement at MNPS were likely (p = 0.91) greater than 30% of MSP and had a I
simulated according to historical information and probability of 0.42 of being larger than 40% of MSP.
{
projections; natural and fishing mortality rates (F)
This simulated recovery, however, assumed that I
were provided by CT DEP. For simulation purposes, changes in fishing regulations were implemented as 4
F was initially set at 0.40 in 1960 and reached a scheduled and that they achieved reductions in l
maximum of 1.33 in 1990. Based on proposed fishing mortality rates as expected.
Even with changes in fishing regulation, F was projected to substantial reductions in fishing. mortality and decrease substantially over the next decade to 0.60 by termination of MNPS operation, the probabilistic 2006 and remain unchanged thereafler, analysis indicated a one in three chance that the new in the SPDM simulation, an initial stock size of equilibrium stock biomass would still be smaller than 113,415 lbs was used to represent the theoretical (no 40% of MSP after 2040. To date, however, the fishing efTects) maximum spawning potential (MSP)
Niantic River winter flounder stock has not shown of the Niantic River female spawning stock. When evidence of a rebound in abundance as suggested by fishing was added, the annual projections of the the model. Even though fishing remains high, this initially untished stock become the baseline time-population has remained resilient and very small series of annual spawning biomass in the absence of adult spawning stocks in recent years have produced any plant impact.
Under the exploitation rates relatively large year-classes of young fish, simulated, as provided by the CT DEP, the stochastic Nevertheless, continued efforts in reducing fishing mean stock size of the baseline declined to 56,243 lbs are necessary to ensure a recovery and avoid a stock by 1970 and to its lowest point of 12,880 lbs in 1993, collapse.
The latter value was less than one-half of a critical stock size, defined as 25% of MSP. Following Lobster Studies simulated reductions in fishing, however, the stock rapidly recovered.
New series of stock size The total number of lobsters caught (all sizes) projections were then simulated by adding the effect and total CPUE in 1996 was within ranges of oflarval entrainment at MNPS. The lowest projected previous years; however, CPUE of legal lobsters 5
stock biomass under simultaneous fishing and MNPS landed in 1996 was the lowest observed in the 3-unit impact again occurred in 1993 (10,604 lbs), whereas period. This decline was expected because total the greatest absolute decline relative to the baseline CPUE in 1995 was the lowest observed in the nearly occurred in 2000 (a ditTerence of 18,682 lbs).
20 year study period, so fewer sublegal-size lobsters Generally, greater rhiucins in stock biomass were available to molt to the legal size class in 1996.
resulted from fishing than from larval entrainment.
There has been an overall decline in legal lobster The simulated spawning stock returned to within abundance since 1978, primarily due to increased about 1,700 lbs of baseline levels in 2030, only 5 fishing rates, which have more than doubled since
J w
1978, and to increases in minimum legal size factors that affect the degree of wave disturbance at i
implemented in 1989 and 1990.
each site. These factors include site orientation to Lobster catches and molting peaked earlier prevailing wind-generated waves, the ability of during the overall 3-unit period (1986-95) than exposed substratum (slope) to dissipate the horizontal during the 2-unit period (1978-85), probably owing force of those waves, and the character of that to the regionally warmer May to August water substratum (e.g., boulders, bedrock ledge).
temperatures observed in recent years. Consistent In addition to these natural factors, impacts 4
with this finding, cooler than normal water related to the MNPS thermal plume have created a temperatures in 1996 delayed lobster catch and distinctive intertidal community on the shore area 4
molting peaks. Other changes in local lobster immediately adjacent to the discharge outfall to the population characteristics during 3-unit operation east (Fox island). The unique algal flora at Fox were related to implementation of new fishery Island-Exposed -(FE), developed under elevated regulations, rather than to power plant impacts. The temperature conditions caused by the 3-unit thennal increased proportion of berried females is associated plume, continued to be evident in 1995-96 based on with the increases in minimum legal size, and should qualitative sampling. There was little change to the increase larval production as a larger proportion of FE flora resulting from the extended 3-unit outage in females are able to spawn before reaching legal size.
1996. The most notable shifts in species occurrence Similarly, implementation of the escape vent at FE during 3-unit operation, relative to unimpacted 4
regulation in 1984 has led to lower percentage of sites, were the presence of warm water-tolerant lobsters missing one or both claws (culls) during 3-species not typical of other sites (Agardhicl/a unit operation.
subulata. Gracilaria tikvahiae and Sargassum The total estimated number of lobster larvae filipendula), absence of common cold water species i
entrained through the MNPS cooling water systems (Mastocarpus 3tellatus, Dumontia contorta and during 1996 was the lowest reported since Polysiphonia lanosa) and extended or reduced 4
entrainment studies began in 1984. This reduction in periods of occurrence of seasonal species with warm 4
entrainment oflarvae was the result of the shutdown water or cold water affinities, respectively.
of MNPS during 1996.
For the most part, Dominant species abundance patterns were entrainment levels have been considerably higher altered by 2-cut water circulation pattems and by 3-during 3-unit operational years relative to 2-unit unit operations only at FE. These changes were most years, due the additional cooling water demand of notable in the low intertidal zone at FE, where Unit 3. The long-term impact of larval entrainment temperature conditions were most severe. The low at MNPS is difficult to quantify because the source of intertidal community at FE, which prior to 1983 had larvae entrained at MNPS is not known, and larval been unimpacted and characterized by perennial survival, settlement and ultimate recruitment to the populations of Fucus, Chondrus and Ascophy//um fishery are not fully understood. Since lobsters and predictable seasonal peaks in barnacle and require 4-5 years ot' growth before they become Monostroma abundance, has been replaced by a vulnerable to capture in our traps and an additional 2 persistent community dominated by Codium. U/ra.
years of growth to reach legal size, continued Enteromorpha and Polysiphonia. These populations monitoring of lobsters will demonstrate the effects, if maintained dominance within the FE intertidal 2
any, of 3-unit operations on the local lobster community during 1996, and small populations of population.
Sargassum and Gracilaria, found only in FE study transects, also persisted.
Rocky Intertidal Studies Elevated temperatures (2-4"C above ambient) at our Ascophyllum station nearest the discharge (FN),
Differences among rocky intertidal stations in coupled with higher than normal ambient community composition were attributed to site-temperatures, may have created unfavorable specific environmental conditions created by the conditions for Ascophr//um growth in 1995-96, influence of many interacting factors. At three of Ascophyllum growth was significantly reduced at FN four study stations, major difTerences among in 1995-96, relative to stations farther away. Owing communities (e.g., based on abundances of the to the high degree of variability associated with dominant taxa such as barnacles, Fucus and Ascophyllum growth, it is not certain whether this Chondrus) were attributed to natural variability in pattern of reduced growth is related to the
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temperature regime. In contrast, thermal incursion in was observed when no thermal plume was produced most previous years caused growth enhancement at at MNPS due to plant shutdown. Therefore, recent FN. Consistent with previous years, Ascophyllum indications of decline at WP were attributed to mortality, or loss of tagged plants and tips, at our natural variability rather than a power plant impact.
present sampling sites was not related to proximity to While declines are apparent for the JC eelgrass 4
the power plant but rather to degree of exposure to population, some improvement in shoot density and storm forces.
standing stock has been observed in the most recent sampling years (1995 and 1996).
The study Eelgrass population at JC is within the predicted thermal i
plume area, and because of shallow water depths Eelgrass (Zostera marina) monitoring studies there (si m), this population is also susceptible to during 1996 revealed relatively healthy study additional stress from solar warming in summer, populations at current sampling sites. The study sites sediment freezing in winter, and waterfowl grazing.
nearest to MNPS, Jordan Cove (JC) and White Point Sediment transport and sand shoaling may also (WP), have supported stable populations since the represent envirormental stress. Elevated temper-study began in 1985. The present study site in the atures relative to those at the MNPS intakes have Niantic River (NR #4) hes only been monitored since been measured directly at JC, and may have caused i
1995; general decline of the overall population in the periodic eelgrass population declines observed there.
Niantic River has necessitated relocation of the study Elevated summer temperatures (by 4-5"C) were site three times over the 12-year study period.
measured in 1996 at JC, and were attributed entirely Variability in population parameters has been to solar warming and water circulation patterns in observed to some extent at all study sites, and was Jordan Cove since MNPS was shut down. Based on j
primarily attributed to factor unrelated to MNPS 1996 findings, these natural factors were largely
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operation.
responsible for temperature Ductuations observed 1
Variability in eelgrass abundance and standing historically at JC, with the MNPS thermal plume only stock has been greatest in the Niantic River. Since a minor influence at most.
1985, this population has been characterized by isolated, often transient patches. The number and Benthie Infauna extent of these patches has declined since early study years, as celgrass at three previous study sites has Benthic infaunal studies during 1996 continued been eliminated. Ecigrass recolonization through to document ongoing community changes related to seed gennination has only been observed once, at the impacts from construction and operation of MNPS.
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original study site (NR #1); this new bed declined This was accomplished by monitoring nearby and was eliminated aller only two years. Causes for subtidal soft-bottom habitats for changes in the instability of eelgrass in the Niantic River are sedimentary characteristics and infaunal community i
unclear, but not related to power plant operation structure (total abundance, species number and because this site is well beyond the zone of inDuence species composition).
Results of these studies of MNPS. No indications of decline have been noted through the 1996 sampling year indicated that MNPS 1
at the current celgrass bed monitored in the Niantic operation-related community changes continued to be River (NR #4), sampled in 1995 and 1996. It observed at the three study sites nearest to MNPS.
remains to be seen whether factors causing declines The only study site not in0uenced by MNPS elsewhere in the river ('perhaps water quality, disease was the GN reference site, located well beyond the j
or waterfowl grazing) will eventually impact the area of possible impacts. Data collected at this site celgrass bed at this site.
continued to reflect long-term physical and biological l
Eelgrass beds at the other sites, WP and JC, stability; sediments collected at GN in 1996 were have persisted over the entire study period; however, similar to previous years, and overall community analyses of some population parameters indicated composition was consistent over the study period.
moderate decline at both sites. De WP population is Speci6cally, the same four taxa (oligochaetes, Tharyx on the fringe of the predicted areal extent of the spp.,
Aricidea catherinae and Mediomastus thermal plume, but temperature monitoring has never ambiseta) have been numerically dominant at similar indicated water temperatures above ambient at that relative abundance levels over both 2-unit and 3-unit site. Furthermore, low standing stock at WP in 1996 operational periods.
i 4
4
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l Two study sites (IN and JC) continued to reflect i
changes related to past isolated physical disturbances from MNPS that occurred over a relatively short duration. In recent years, sediment silt / clay content has declined to near pre-impact levels and indications of community recovery are evident through 1996.
Species richness and abundances of oligochaetes and Aricidea catherinae (common taxa prior to 1983) have increased, while abundances of more opportunistic species (e.g., Nucula proxima) have declined. Ilowever, continued dominance of post-1 impact species, such as Tharyx spp., indicates the recovery is still ongoing at IN.
liabitat and community changes resulting from another past disturbance event attributed to MNPS operation were still evident at JC in 1996.
Specifically, the effects of siltation at JC afler the start-up of Unit 3 in 1986, associated with increased cooling water flow and sediment scour in the j
immediate area of the discharge, continued to be observed in 1996. Abundances of the previously dominant oligochaetes, and the polychaetes l
Polycirrus eximius and Aricidca catherinae quickly decreased. The impact of this siltation event has apparently lessened since 1986, as populations of some 2-unit period dominants (e.g., A. catherinac) have recovered.110 wever, long-term persistence of some of the deposited silt clay was still evident aller i
/
1995 sampling, and community recovery is evident j
but slow at JC.
Discharge scour directly and continuously impacts the sedimentary environment and the infaunal community at EF. Sediments in 1996 were characterized by increased sediment grain size and decreased silt / clay levels relative to 2-unit operational years. The infaunal community at EF has developed under the new, relatively stable, high current conditions in the discharge area. Populations of species common during 2-unit operation (e.g., A.
catherinae and P. cximius) have returned to EF, while other species (including Tharyx spp.) have declined or do not occur even during periods of area-wide increase (e.g., M ambiseta). Little change in the impacted infaunal community at EF was observed during 1996, when MNPS was shut down. This indicates that this community will likely persist for some time after sediment scour produced by the MNPS discharge ceases.
ATTACIIMENT 2 to the Millstone Unit 3 Environmental Protection Plan Annual Environmental Protection Plan Operating Report January 1 - December 31,1996 1
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l M<mitoring the Marine I inironment i
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