ML20247J985
| ML20247J985 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 08/09/1988 |
| From: | CAROLINA POWER & LIGHT CO. |
| To: | |
| Shared Package | |
| ML20247J876 | List: |
| References | |
| NUDOCS 8907310409 | |
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Text
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Enclo2ure 3 Clogging of Fine-mesh Screens by Capre111d Amphipods Brunswick Biology Laboratory Environmental Services Section CP&L August 9, 1988 l
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List of Tables and Figures Table 1.
Sampling regime and densities of capre111d amphipods collected j
from July 12 through July 25, 1988.
Figure 1. Male, CapreIIa equilibra, indicating important di stingui shing identifying characteristics.
1 Figure 2.
Female, CapreIIa equilibra, indicating important distinguishing l
identifying characteristics.
J Figure
- 3. Male, Caprella penantic, indi cating important di sti ngui shing i denti fyi ng characteri sti cs.
i Figure 4.
Female, CapreIIa penantis, indicating important distinguishing
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identifying characteri sti cs.
Fi gure
- 5. Entrained caprellid amphipod densi ties from July 12 through July 20,1988.
Figure 6.
Sali ni ty values from the BSEP return flume for day and night from July 1987 through July 1988.
j Figure 7.
Entrained capre111d amphipod densities through Unit 1 and Unit 2 on July 20, 1988.
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. 'x.y Introduction On July 15, 1988, at approximately 0250, circulating: water (CW) -
1otake pumps IC, ID, 2A, 2B, and 2C tripped = due - to high. differential-screen pressure (A P).
Intensive testing by Plant I&C personnel - showed -
that actual high A P across the screens. and-not instrument failure or false readings caused the CW pumps to trip.
This raised the question of screen cloggi ng by marine organi sms'.-
Numerous biological samples were taken and indicated that little aquatic vegetation, very few hydromedusae, and no ab' normal amounts of detritus were present. :(These ' items have pre-l viously clogged the fine-mesh screens. ). Af ter several attempts to restart the pumps, the fine-mesh screens were removed.- Large numbers of capre111d '
amphipods were found impinged on these fine-mesh screens during their re-moval.
In addition, large number of the ' organisms were-caught downstream of the pumps upon start-up.
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Caprellid amphipods are temperate and cosmopolitan marine amphipods that are highly modified for a semi-sessile life among filamentous algae, I
hydroi ds,
- bryozoan, and other marine fouling organisms (Bynum 1978-1980).
These slender, elongate " skeleton shrimp" seldom grow larger than 15 mm (Gosner 1971).
The morphology of caprellids allows them to: cling to' the substrate despite heavy wave action or strong currents. The y>ung re--
1 semble small adults and hatch from eggs carried in the female's brood pouch from which they emerge and become free-living.
These amphipods have a two generation life cycle with overwintering adults producing a large spring peak of abundance, followed by a summer i
die of f.
Those organisms hatched during spring become young adults and those young adults that last through the summer produce a sinaller fall j
peak (Bynum 1978).
Hi gh concentrations of amphipods have recently been I
reported on the North Carolina coast (Hogarth, pers. com.) and. are not uncommon.. Substrates sometimes become heavily crowded with capre lids and many times are two to three organisms deep (Dynum, pers. com.).
These organisms have been known to exhibit massive migrations by the millions as i
1 a response to low dissolved oxygen, low salinities, or other stimuli
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(Heard pers. com. )'
The species of capre111d hmpnipod reported here cannot tolerate salinities. below 24-25 ppt and prefer salinities from 30-32 ppt.
This report ' attempts to address questions rai sed concerning the capre111d amphipod's probable role-in tripping the intake pumps on' July 15, 1988.
Methods llumerous samples were taken from July 12 through July 25 to estimate.
the densi ty of capre111d amphipods. in the intake. area.-
Thirty-ei ght plankton samples from the discharge weir,. nine plankton samples from - the return fiume, nine plankton tows ' from the intake - canal and adjacent Cape Fear River (CFR), 'and four. substrate samples from hydroid and bryozoan colonies in the intake area were collected and' processed -(Table 1).
3 Raw numbers and densi ties ' (#/m ) were calculated for all entrainment and plankton tows while densities were calculated in (#/in ) for substrate!
2 samples.
An estimate of abundance was made for the samples collected.from the return flume since heavy debris caused difficulty in processing..
Water quali ty - (sali ni ty) measured during the. ' regular. ~ monitoring program was evaluated to obtain estimates of' when -the salinity was high for extended periods'.
1 Results and Discussion 1
The capre111d amphipod was identi fled as Capretta equilibra.
Two distinct characteristics of thit, particular capre111d are:
1-the' cephalon' (head) has no anterior projection (Figure 1) 2-a ventral spine is; present between insertions of-gnathopods 2 (Figure 2).
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'l A similar species Capre11a. penantic whicn is used for ' many assumptions i
stated in this report (Figures.3 and 4).
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Entrainment sampling at. the - discharge weir on. Unit II substantiated,.
1 the high concentrations of capre111ds on the fine-mesh screening (Figure
- 5).-
Entrainment samples taken on the afternoon of.7/15/88 indicated that l
caprellids. passed. t'hrough ' the plant at ' ensi ties of 3000/m.
The densit-l d
3 1es of capre111ds-steadily dect eased 'through 7/20/88 with only 3.6/m j re-f 3
ported.
Densities between 4.and 44/m3 calculated from entrainment samples.
taken on 7/12/88 and 7/13/88 prior to :the pumps tripping on-7/15/88 were reported and may have been.a precursor to the event ore 7/15/88.
These numbers are substantial due to the fact that on these days, three of the four traveling screens were fisted with; fine-mesh, while those taken after
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the rmrning of 7/15/88 were all. 3/8-inch mesh.
j Col.ecti ons in the return fiume - i ndi cated similar results (Tabic 1).
Although actual counts of caprellid amphipods in the flume were not made, estimates of the densities from the five-minute. samples suggested -
heavy concentrations on 7/15/88, fewer numbers were found the next three i
days, with the numbers decreasing to.only a few on 7/19/88.
Plankton samples from the intake and nearby Cape Fear River on the morning of July 16 and the evening of July 18 indicated very few caprel-lids present in the water column (Tabl e ' 1).
This was expected since the caprelli ds are somewhat " arboreal" in their association with hydroids, bryozoans, algae, and seagrasses (Barnes,1968).
Estimates of the caprellid densities on the traveling screen frames taken on 7/20/88 during the maintenance work on 28 indicated between 20 and 26 capre111ds/in2 of substrate..This number is not surprisingly high (Heard pers com. ).
However, the fact that traveling screen ' 2B had been pulled out of the water three times prior to the substrate sampling may have attri buted to a lower estimate of capre111d numbers than were ori gi nally present.
Substra te samples taken or, 7/25/88, i ndi cated no caprelli ds present on the hydroi ds or bryozoans.
Thi s probably was a result of the intense thunderstorms in the area on 7/15/88 'and 7/16/88 i
which lowered the salinity to 21 ppt on Monday.
This is below the lower tolerance level for C. penantic and C. equiHbra.
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.p Water quali ty data duri ng the past twelve mnths show no unusual peaks in the salinity (Figure 6).
The typical summer increase in salinity is evident.
However, the increase began earlier in 1988 than in 1987 due to the dry spring of e'88.
This may have increased the habitat preferred by caprellids.
An intense entrainment sampling effort was conducted on 7/20/88.
It was hypothesized that perhaps the backwash from a tripped pump upsteam could cause a downstream mvement of these organisms.
Effort was cade to simulate the activities that occurred when the pumps tripped. Circulating water pump A was started, then intake CW pump C was turned off to see if the number of caprellids would increase due to pump shutdown and subse-quent back flushing through the screen.
The number of caprellids col-lected during thi s simulation was not comparable to those collected on 7/15/88.
The results only indicated a higher concentration, of caprellids passing through Unit II as compared to Uni t I (Fi gure 7).
Thi s was ex-pected since Unit I filtered the water wi th one fine-mesh screen operating and Unit II was using all 3/8-inch mesh screens.
Summary and Conclusions All indications suggest that the large number of caprellid amphipods prior to, duri ng, and immediately after the tripping of the CW pumps, actually blocked the fi ne-me sh screens creati ng the high A P.
This conclusion is supported by operations inability to start the pumps with the fine-mesh screens in place and their ability to restart the pumps once the fine-mesh screens were removed.
Caprellid amphipods exhibit a semi -sessi le life among hydrof ds and bryozoans.
Their numbers are a di rect reflection of substrate a vail-a bi li ty, subsequently when hydroi d and bryozoan growth is accelerated j
during summer months, the densities of caprellids will probably increase also.
The salini ties over the past month were frequently over 30 ppt, whi ch thi s species of amphipod prefers.
Therefore, the densities were l
probably greater than they have been in the past.
It appears that the I
,'y release from the substrate of these organisms was triggered by some change in water quali ty (i.e.
chlori ne, low D.0.,
lo( sali ni ty, etc. ).
Whatever tri ggered the capre111 d amphipods to become impinged on the fi ne-mesh screens in front of CW pump IC possibly moved down the canal with the currents (and roving large numbers of capre111ds with it) creating similar A P problems with successive fine mesh screens subsequently tripping each pump.
The problem with the capre111d amphipods seems to have ended.
The intense rainfall on 7/22-23/88 caused massive migrations and/or die-offs of the caprellids which can not tolerate salinities below 25 ppt.
Salin-ity on 7/25/88 was around 21 ppt on the surface.
Substrate and entrainment samples verified the drastic decrease in the numbers of the capreilid amphipod present in the intake canal.
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Table 1.
Sampling regime and densities: of capre111d amphipods= from July 12 through July 25, 1988.
3 Date Type-1 Ti ne Raw # Densi ty (#/m )(reps)
Tuesday July 12 Entrai nment 1000 276 4.6 1300 375 6.6 1600 250 4.0 2200
. 567 10.1!
Wednesday July 13 Entrai nment 0100 1867L 44.0 0400'
. 1867 31.2 Friday July 15 Entrainment SS*
1730 126,350 2980.0-1800 7233 170.6 Larval Imp SS 1730 Heavy 1800 Heavy Saturday July 16 Larval Imp SS 0650 Abundant Entrainment SS 0900 1517-26.0 Plankton SST (I) 0954 11 (0) 1029 0
(SH) 1038 2
Entrainment SS 1129 1200 21.6 Larval Imp SS 2111 Abundant Entrainment SS 2125 1080 19.5 Sunday July 17 Entrainment SS 0750-500 9.0 Larval Imp SS 0810 Present 2132 Present Entrainment SS 2147 500 9.0 Monday July 18 Entrainment SS 0800 600 10.8 3
Plankton SS (25-S&B) 2100-0 (19-S&B) '2130 0
(15-SaB) 2145 0
Entrai nment SS-2130 233 4.0 Larval Imp SS 2145 Scarce-Tuesday July 19 Larval Imp SS 1100 Scarce 2300 Scarce Hednesday July 20 Entrainment SS 0100 183 3.6 Substrate SS
-1030 471/1244 19.6/25.9' Entrainment SS (U1) 1559 67/120
'2.0/3.6 1606 61/93 1.7/2.7 1615 51/63 1.6/1.9 1624 31/51 0.9/1.6 1630 46/55 1.5/1.8 1639 32/17 1.0/0.6 i
(U2) 1600 1022/1170 17.3/20.4 l
1607 1360/1850 24.9/33.9 1
1614 1100/1334 19.4/23.5 1623 1500/1250 26.9/22.4 1633 2100/2183 52.8/41.3 Monday July 25 Substrate SS 1130 0
- SS =speci al study.
9 I' =inside intake canal, 0=outside intake canal, SM= snow's marsh.
$ buoys 25,19,15 (surface and bottom).
- U1 = uni t 1 U2 = uni t 2.
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Fi gure 1.
Male, CaprcIla equilibra, i ndi ca ti ng i mportant di s ti ngui shi ng iden ti fyi ng characteri sti cs.
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Female, CaprcIla equilibra, i ndi cati ng i nportant di s ti ngui shing i denti fyi ng characteri $ ti cs.
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- 3. Male, CapreIIa penantis, indi ca ti ng i mportant di s ti ngui shing identi fyi ng characteri sti cs.
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Figure 4 Femal e, Caprella penancic, indi cating important di stinguishing iden ti fyi ng characteri sti cs.
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ENTRAINED CAPRELLID DENSITIES JULY 12 - J%Y 20.1966 a.._
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Entrained caprellid amphipod densities through Unit 1 and I
Unit 2 on July 20, 1988.
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List of References Barnes, R.D.
1968.
Invertebrate Zoology.
' Press. of W.B. Saunders Co.
Philadelphia, PA.
- Bynum, K.H.
1978.
Reproducti ve biology of CapreIIa penantis, 1814 (Amphi poda: Caprellidae) in North Carolina, USA.
Esturine and Coastal lbr. Sci. 7:473-485.
Bynum, K.H.
1980.
Multivariate assessment of morphological variation in CapreIIa penantis
- Leach, 1814 (Amphi poda:
Capelli dae).
l Estuari ne and Coastal Mar. Sci. 10:225-237.
- Bynum, K. H.
1988.
Personal Communication.
Dept. of Zoology, University of North Carolina, Chapel Hill, NC.
- Gosner, K.L.
1971.
Gui de to identi fication of mari ne and esuari ne i vertebrates. John ', liley and Sons.
- Heard, R.W.
1988.
Personal Communi ca ti on.
Gul f Coast Lab, Ocean Spri ngs, MS.
- Hogarth, ll. T.
1988.
Personal Communi ca ti on.
- Di vi sion of Marine Fi sheries, Morehead Ci ty, NC.
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State of North Carolina Department of Natural Resources and Community Development Division of Environmental Management 512 North Salisburygtg* Pfeighgh Carolina 27611 James C. Martin, Governor CERTIFIED MAIL R. Paul Wilms S. Thomas Rhodes, Sectrtary RETURN RECEIPT REQUESTED Director Mr.
G.
H.
Warriner Carolina Power & Light Company Route 1,
Box 327 New Hill, NC 27562
Subject:
Permit No. NC0007064 Brunswick. Power Plant Brunswick County
Dear Mr. Warriner:
In accordance with your application for discharge permit received on July 1, 1985, we are forwarding herewith the subject State - NPDES permit.
This permit is issued pursuant to the requirements of North Carolina General Statute 143-215.1 and the Memorandum of Agreement between North Carolina and the US Environmental Protection Agency dated December 6, 1983.
l If any parts, measurement frequencies or sampling requirements
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contained in this permit are unacceptohle to you, you may request a waiver or modification pursuant to Regulation 15 NCAC 2B.0508(b) by written request to the Director identifying the specific issues to be contended.
Unless such request is made within 30 days following receipt of this permit, this permit shall be final and binding.
Should your request be denied, you l
will have the right to request an adjudicatory hearing.
l l
Please take notice that this permit is not transferable.
Part II, B.2.
addresses the requirements to be followed in case of change in ownership or control of this discharge.
This permit does not affect the legal requirement to obtain other permits which may be required by the Division of Environments.1 Management or permits required by the Division of Land Resources, Coastal Area Management Act or any other Federal or Local governmental permit that may be required.
If you have any questions concerning this permit, please contact Mr.
Dale Overcash, at telephone number 919/733-5083.
Sincerely, R.
Paul Wilms cc:
Mr. Jim Patrick, EPA Wilmington Regional Supervisor lkilutwn Presentwa Pays P.O. B x 27687, Raleigh, Nonh Camhna 2760-7687 Telephone 914733-7015 An Equal Opportunrry Afhrmanve Acnon Employer
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