Text

Offsite Chlorine Minimization Study 1987
	ML20246B834
Person / Time
Site:	Seabrook
Issue date:	12/31/1987
From:	; NORMANDEAU ASSOCIATES, INC.
To:	;
Shared Package
ML20246B660	List: ML20246B657; ML20246B697; ML20246B717; ML20246B743; ML20246B834;
References
	NUDOCS 8905090185
	Download: ML20246B834 (69)
	v • d • e

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

' ATTACHMENT 4 SEABROOK STATION OFFSITE CHLORINE MINIMIZATION STUDY 1987 Prepared for NEW HAMPSHIRE YANKEE DIVISION .

Public Service Company of New Hampshire Seabrook Station P.O. Box 700 Seabrook, New Hampshire 03'874' Prepared by NORMANDEAU ASSOCIATES'INC.

25 Nashua Road Bedford, New Hampshire 03102

.i i

R-583 '

JULY 1988 8905090185 890428 I PDR ADOCK 05000443 R PDC 1

]

C___________.___.__.._______._________-._ _

,)

i 1

1

, . J TABLE OF CONTENTS j PAGE l

1.0 INTRODUCTION

. . . . . . . . . . . . . . . . 1 i 2.0 METHODS . . . . . . . - . . . . . . . . ' . . . . 4 2.1 GENERAL APPROACH . . . . . . . . .. . . 4 2.2 SYSTEM DESIGN. . . . . . . . . . . . . . 4 2.2.1 Chlorine Demand Study . . . . . . 4 j 2.2.2 Chlorine Flow Study . . . . . . . 7 l

2.3 CHEMICAL / PHYSICAL DATA . . . . . . . . . 9 2.3.1 Instrumentation . . . . . . . . . 9 2.3.2 Sampling for Experimental Data. . . . . . . . . . . . . . . 10 !

2.3.3 Pilot Study NPDES Required l Sampling. . . . . . . . . . . . . 10 2.4 BIOLOGICAL DATA. . . . . . . . . . . . . 11 2.4.1 Sampling. . . . . . . . . . . . . 11 2.5 DATA ANALYSIS. . . . . . . . . . . . . . 11 2.5.1 Data Reduction. . . . . . . . . . 11 3.0 RESULTS . . . . . . . . . . . . . . . . . . . 13 f I

3.1 CHLORINE DEMAND STUDY #1: {

(April 10 - May 26). . . . . . .. . . . - 13 '

3.2 CHLORINE DEMAND STUDY #2: J (June 27 - August 7) . . . . . . . . . . 18 l f

3.3 FLOW RATE STUDY. . . . . . . . . . . . . 21 J 3.4 CHLORINE DEMAND STUDY #3:

(August 14 - September 25) . . . . . . . 25 1

I 3.5 CHLORINE DEMAND STUDY #4:

(September 28 - November 9). . . . . . . . 28 l

t

1

. )

g 1

IABLE OF CONTENTS PAGE 4.0 DISCUSSION. . . . . . . . . . . . . . . . . 35 4.1 CHLORINE DEMAND. . . . . . . . . . . . 35 4.2 BIOFOULING . . . . . . . . . . . . .. 35 4.3 OTHER DATA . . . . . . . . . . . . . . 44 5.0 LITERATURE CITED. . . . . . . .. . . . . . . 50 6.0 APPENDIX TABLES . . . . . . . . . . . . . . 51 l

l

i *

1.0 INTRODUCTION

i The United States Environmental Protection Agency (U.S.

EPA) has issued an NPDES Permit (No. NH0023308) to license Seabrook Station's environmental discharges. The permit requires, among other things, that the permittee conduct a chlorine minimization study to determine the least amount of chlorine that will be required to provide satisfactory macroinvertebrate control within the Circulating Water and Service Water Systems. To accomplish this, an off-site pilot study was undertaken to answer initial chlorine minimization questions and provide guidance for the Station's operational program.

With this in mind, the off-site pilot plant was designed to simulate the intake tunnel system to answer two questions:

1. What injection levels of chlorine are effective in controlling biofouling up to a point 90 minutes downstream of the injection point?

2. What is the seasonal variability in instantaneous and 90-minute chlorine demand of nearshore seawater, and what is the variability in the resulting total residual oxidant levels?

Because of the unavailability of a local open-ocean site, the pilot plant was set up in Hampton Harbor. As a result, some unique approaches had to be undertaken in order to carry out this study, The results must be interpreted in light of study restrictions caused by the site location and design parameters sought by U.S. EPA.

This report provides data obtained at the off-site test facility and will be evaluated against similar data collected during the same period at Seabrook Station. Actual operational data will also be evaluated to verify the program necessary to control biofouling at Seabrook Station.

Biofoulina Summary The off-site chlorine minimization study conducted during the active biological settling periods for the year (April-November) demonstrated that biocide control varied with the species. Four macroinvertebrate taxa were the dominant settling organisms in this study: Balanus sp.

(barnacles), Mytilidae (mussel spat), Anomia sp. (j ingle shell) and hydroids.

1

I 1

{

1 I

During the spring study (April 10 - May 26), more ;

barnacles were found in the 1.0 ppm treatment level than at {

either the control (no chlorine added), or at the lower ;

treatments. Settlement control was ' observed at I concentrations greater than the- 1.0 ppm treatment i concentration. Other studies have shown that barnacles can cover up to 100% of a surface upon' settlement, however {

natural mortality from crowding usually decreases its ,

numbers after a few months. Either way, this species may '

roughen the substrate, thereby enhancing later fouling by I other species. l

,l During the early summer study (June 27 - Aug 9), mussel j spat (primarily Mytilus edulis) were abundant both on test j panels with no chlorine treatment (control) and on offshore l (discharge site) panels. No mussels were found on any of i the chlorine treatment panels (0.75 1.50 ppm dosage), j indicating adequate biocide control of this species at these l levels. j l

During the late summer study (Aug 14 -

Sept 26),

settlement was very sparse on test panels. This was also observed on panels in the natural environment. Ac a result, ;

a number of panels'from the third study were maintained and exposed to chlorine treatments for 90 days, extending '

i through the fourth demand study -(Nov 11). Biofouling results from this extended exposure were similar to the 45 day exposure results from the fourth (fall) study, as discussed below.

During the fall study (Sept 28 - Nov 11), hydroids were common on panels at the test facility and those located offshore. Settlement patterns in the test facility were observed to be very patchy (variable), connistent with that seen offshore which could explain differences within the test system. Dosages of up to 0.75 ppm did not noticeably discourage hydroid settlement in these = tests. A minimal number of mussels were also observed as settled during this study period. These results were reinforced by data collected from tubes connecting the tanks in each treatment line. After over 90 days of exposure, some mussels'were found at chlorine levels up.to the 0.75' ppm treatment (dosage) level. The mean final TRO values at a treatment level of 0.75 ppm, ranged from 0.19 ppm to 0.26 ppm.

2

6 t

l 1

Chlorine Demand Summary Chlorine demand varied throughout this study.as.a result' of the treatment level- (dosage) , and through time 1as '

a . - result of seasonal ' variations in water . quality. The' greatest differences were' .a . result of ' chlorine treatment level. Demand increased'with-increasing dosage.for1the levels; tested in this study.- However, the percent of. dosage demand decreased with increasing input, reflecting increased

' saturation' by chlorine.- Demand was fairly' constant? and highest during the spring and early; summer, .with lowest demand during the fall, as; evidenced by the demand at the 1.0 ppm' dosage level.

Identifying - dosage levels that resulted in total residual oxidant '(TRO) levels below the 0.2 ppm threshold set by the. Station's NPDES permit was a goal.of,this: study.

Final (90 minute) TRO readings at the lower (0.25 and--0.50 ppm) dosages wsre'all below'the 0.2 ' ppm level with two exceptions, one each in the third and fourth studies. These two dates marked unusuallyL low demand at all treatment levels. At the intermediate-test dosages (0.75 and 1.0 ppm), the number of 0.2 ppm'exce.edances-' increased over the year. At 0.75 ppm, the parcent of-TRO values' exceeding'O.2 ppm were 0%, 37% and 67% during tests two, three and four respectively, while'at 1.00 ppm dosage,-the percentages greater than 0.2 ppm were 32%, 25%, 84% and 100% across the four tests.

These results indicate that the. maximum dosage necessary in. order to maintain TRO values less than.or. equal to 0.2 ppm, 90 minutes later, would be lower than 0.75 ppm and could occasionally be as low as 0.5 ppm (as . observed during the third and fourth test periods)._ This does not '

consider the affects of the additional transit time' at an elevated temperature until . discharge to the- environment..

With the exception of the final demand study, the of fsite test facility was cleaned following each study period. The operation of the Circulating Water System at Seabrook Station will result in some degree of fo.uling which may increase the demand within the system. .In these studies,.

the demand (and therefore the' maximum dosage allowable to remain under the 0. 2 . ppm threshold) varied. seasonally and was found to be highest in the spring.

3 s

_____________.______.____________m___ . _ _ _ _ _. _ _ _ _ . __ _ _ . . . _ _ _ .

, a 2.0 METHODS 2.1 GENERAL APPROACH This pilot study was designed to simulate the conditions in the intake tunnel system within practicable limitations. Although it would have been preferable to simulate both retention time and velocity in one experiment, site restrictions dictated - otherwise'. Hampton Harbor, the- .j site chosen for this study, was 'seen to have similar water i quality to offshore (intake) water during the four-hour.

period around high tide.. Therefore, water had.to be L collected within this four-hour period and stored for use 1 during the remainder of the tidal cycle. .An attempt to l simulate the velocity within the intake tunnel (3.8 ft/sec -

4.0 ft/sec) would have required a 300,000-gallon storage tank,.and the physical size of the pilot equipment would have been excessive. Therefore, after careful 1 I

consideration, a velocity of 0.25 ft/sec was selected to test different chlorine demand levels over a 90-minute retention period, (the approximate travel time through the intake tunnel). This velocity allowed a pilot system of 3 reasonable size for the quantity of water to be handled to j obtain a 90-minute retention time.' t j

A goal'of this study was'to determine.the minimum amount of chlorine required to control biofouling yet remain within the Station's. discharge limits for total residual oxidant (TRO). For this reason the tests were carried out during the major periods of biological activity (April-November).

A separate experiment was undertaken to correlate biofouling with water velocity. A relatively simple system was set up using velocities of 0.25 ft/sec, 1.0 ft/sec, and 4.0 ft/sec to study the ef fect of velocity on biofouling rates. A target chlorine level' of 0.75 ppm was chosen for this experiment. Results from this study were compared to i results of the chlorine dosage study, run at 0.25 ft/sec, '

l thus placing into perspective biofouling differences attributable to water velocity differences.

2.2 SYSTEM DESIGN 2.2.1 Chlorine Demand Study The chlorine demand study system is shown schematically in Figure 2.2 l. It consisted of the following elements:

o Seawater irtake pump ,

o Seawater collection tank '

o Seawater supply system i

'4 j

)

, _ _ _ _ _ _ . _ . . l

-. j l

I seawater storage tank,. sump tank,. sodium thiosulphate tank, and sodium hypochlorite ' _ tank. ..Also provided were annunciator lights to . indicate. alarm. conditions due to system abnormalities (reduced or zero flow-in any line, pump failure, or . a low ' supply of Lseawater or. process chemicals)'.

The process' control panel also housed controlling relay _

logic:to safeguard against, or. alarm of, a test. parameter l

' going askew.- Also, . subsystems would be automatically. shut

~down if a' key function failed.

1 Test periods covered the spring, early summer, late. !

summer and fall (Table . 2. 2-1) . During the first study,-a' wide range of treatments . ware : used sinceLit was L not :known how much the 90-minute. demand would vary. Based on-the results of the first study, it was clear that the ! highest - '

input level, 2.0 ppm, resulted in a'high. total residual oxidant (TRO) . concentration' This input concentration was j{

therefore eliminated.from further. tests and a.mid-range -

concentration.of 1.25. ppm added. The lowest treatment.

level in the second : study was:' increased from 0 ; 50 ppm .to -

0.75 ppm, anticipating that there would be higher demand during the early summer (second) test. Since the final (90--

min.). demand did not increase during the second test,. lower.

treatment levels . were initiated - (0.25 and 0.50 . ppm) . in the -

third test and. carried through the fourth. ..The two highest levels from the second study were also . subsequently dropped as final TRO was still too high for NPDES permit levels at Seabrook Station.

Quality control elements were included in the operation 1 of the chlorine study pilot plant to insure quality data j collection. Checks involved periodic calibration checks of l flow meters, chemical feed pumps, and the actual' flow rate in each experimental line. The concentration .of chemical stocks was checked weekly or more frequently if warranted.-

2.2.2 Flow Rate Study The flow rate study system is shown schematically in Figure 2.2-1. It consisted of.the following elements:

o seawater intake pump and strainer !

o ' chlorination equipment ,

o Three flow-through test cells o Dechlorination equipment- 'l The seawater intake consisted'of a coarse strainer on a submerged pump that was capable of delivering 230 gpm to the i flow study. The actual amount of water delivered to the test apparatus was controlled .to 210 gpm by a compensating. j pressure valve that diverted any excess water to the 7 !

.)

n

, . INTAKE _-

COLLECTION 18.000 GPO ~ TANK j f 12.5 GPM f% /% Y%

j p j p 2.5 GPM Jf j [ 2.5 GPM J f j [ 2.5 GPM j [j f 2.5 GPM J f 2.5 GPM EST CONC EST CONC. 4 CONTROL fEST CONC.EST CONC.

1f U ! t U CHLORINE u DEMAND STUDY CHLORINATION l I

+ (Sodium Hypo-chlorite) 10 GPM COLLECTION _

TANK 12.5 GPM I

DECHLoRINAlloN .

(Sodium Thio- -

sulfate) 1I 1

1I

= MIXER Z j l i l I l (TEST CELLTEST 1 CELL 2) (TEST CELL 3 FLOW d ' l d RATE 10 GPM 40 GPM 160 GPM STUDY ll

- 1 II MIXER DISCHARGE 222.5 GPM i l INTAKE 210 GPM Figure 2.2-1. Schematic of pilot plant design for the Seabrook Chlorine Demand Study and the Flow Rate Study. Seabrook Chlorine Minimization Study,1987.

5

, i 4

1 o Five flow-through test systems with 90-minute retention o Chlorination / Dechlorination equipment o TRO analytical equipment o Support facilities.

The seawater intake pump was capable of-pumping.120 gpm l into a 13,000 gallon. storage tank. This pump was controlled 'J by a programmable timer and operated during the forty minute l' period before, and fifty minute period after high tide, to accumulate suf ficient ' seawater . to supply the needs-of the system for 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The storage tank had_a built-in i circulation system to maintain organisms in suspension.

Seawater was. pumped into the. test system through a. pressure control valve; excess water was returned to the storage tank. i The test system consisted of five test lines; four treatment lines and one ' control' line. Each test line consisted of five sequential tanks (barrels) with stirrers.

The first and last tanks within each line contained six 4" x l 4" roughened plexiglass test panels. The mixing velocity.in !

each tank was such that . the water velocity over the test panels was approximately 0.25 ft/sec. The_ stirred tanks ]

were arranged with gravity flow from one to another which allowed for an approximate 90-minute retention time from input into the first test tank to exit from the fifth tank.

The flow of seawater into'each test line was maintained at approximately 2.5 gallons per minute (gpm) by a needle valve and flow sensor. Feedback from this device in turn ,

i controlled the pumping rate of a sodium hypochlorite pump to insure constant concentrations of hypochlorite during the ;

tests. The hypochlorite solution was injected into the '

seawater and mixed in a static mixer just prior to entering i the first tank. During each study period, four test lines were run at four different treatment levels of chlorine. A fifth test line was utilized as the control and was not chlorinated.

The seawater exiting from all test lines, was collected ;

in a sump tank, and pumped through a flow sensor and a static mixer. The flow sensor output drove a chemical feed i pump which injected a sodium thiosulfate ' solution into the static mixer to dechlorinate the discharge from the test >

system.

To ensure good control of the pilot plant, a process control panel was utilized. This provided readouts on supply flow rates, discharge flow rates, total. accumulated flow and sump tank level. It included level alarms'for the t

6

TABLE 2.2-1. DEMAND AND FLOW'S'TUDY DATES AND CONCENTRATIONS.

SEABROOK CHLORINE MINIMIZATION STUDY, 1987.

TARGET STUDY TYPE DATE CHLORINE CONCENTRATION Demand Study 1 4/10 - 5/26 Row 1 0.00 ppm Row 2 0.50 ppm Row 3 1.00 ppm Row 4 1.50 ppm ,

Row 5 2.00 ppm i Demand Study 2 6/27 - 8/9 Row 1 0.00 ppm Row 2 0.75 ppm I Row 3 1.00 ppm Row 4 1.25 ppm I Row 5 1.50 ppm ;

Flow Study 1 6/26 - 8/9 All Lines 0.75 ppm i Flow rates of- l 0.25,1.0,4.0 fps l i

Demand Study 3 8/14 - 9/26 Row 1 0.00 ppm-Row 2 'O.25 ppm !

Row 3 0.50 ppm Row 4 0.75 ppm Row 5 1.00 ppm Demand Study 4 9/28 - 11/11 Row 1 0.00 ppm l

Row 2 0.25 ppm Row 3 0.50 ppm ,

Row,4 0.75 ppm Row 5 1.00 ppm I

8

0 1

/

4

( c)

ES Y RE 4 D OK 4 2 4 4 U HA . . . .

T ST 8 A A 0 0 0 S FN 2 N N 3 3 3 FI D O(

N A

M )

E o D c b

/ N E o OR 5 0 2 2 2 1 N ( TO . . . . . .

I PB 7 8 7 8 0 0 R Y MR 2 2 2 2 3 3 D T AA I I HH H N C . I 7 L T8 A ) ) ) ) ) )

S9 S 5 0 2 3 4 5 R1 ) . . . . . .

I " . 0 1 1 0 0 0 F , D D ( ( ( ( ( (

Y NY .

GD ADS 3 1 0 9 8 6 NU MU( . . . . . .

IT ET 7 8 9 8 9 9 RS DSx 2 2 2 2 2 2 U

DN O

DI ET DA c)

RZ ES OI RE CM OK EI HA 2 9 5 0 RN ST . . . .

I FN 5 A A 5 6 8 AM FI N N T O(

AE )

DN C I O YR ( D TO N IL E OR NH R TO 3 9 9 6 3 6 IC U PB . . . . . .

L T MR 6 8 4 8 9 1 AK A AA 1 SO R HH O E DR P NB M AA E E T ) )

ES ) ) ) ) ) 8 4 k R 8 . 6 7 0 4 . . e U D D . . . n 0 e T .

NY . 0 0 1 1 ( ( w AK ADS ( ( ( (

RE MU( 3 7 r EE ET 0 0 2 8 . . e PW DSx . . . . 0 0 sp M 7 8 7 8 1 1 y EY ae TB dc e nkl 7oeb 5

. ) ) )

f ,wl ea 8 ) ) 9 6 1

- ) 2 5 2 1 2 oe i 1 / / 1 / / dra

. 2 4 5 / 5 5 eiev 3 / 5 gt p a K 4 - - - - a E E - -

- rhet L E 10 22 39 4 53 60 egco B W 1 2 2 6 - 1 2 vinN A / / / / / / AHo:

T 4 4 4 5 5 5 a"cA

( ( ( ( ( ( N ll

I discharge.

Each of the'three test cells consisted of a PVC tuba 4-feet long by 4 inches in diameter into ' which :were placed four 4" x 4" roughened plexiglass test panels. The piping.

of each of the test cells was of a different size to deliver-water from a common manifold at different rates to each test' cell. The flow to. cell #1 was controlled through valving to L 10 gallons per minute -(gym) , yielding a theoretical _ flow over the test panels inside the cell of 0.25 feet per second (fps). . Test cell #2 received 40 gym, producing a calculated flow of 1 fps over the test panels, while test cell #3 received 160 gym, resulted in a velocity _of 4 fps over the test panels.

3 Since flow'to all three test cells was supplied through a manifold f rom ' a - common chlorinated supply, chlorine concentrations in each, test cell .were the same. This'was accomplished by'a chemical feed pump inj ecting a' 12. 5%

solution (by weight) ,- 'of ~ sodium hypochlorite into a ' static mixer just upstream of the manifold. Input target-The chlorination discharge fromwasthe0.75 testppm

-over the apparatus was study period. -'with dechlorinated sodium thiosulphate, then combined within'a common discharge l with flow from the demand study.

2.3 CHEMICAL / PHYSICAL DAT&

2.3.1 Instrumentation Samples were analyzed for total residual oxidant (TRO) using an ORION ion Analyzer EA 920, with the ' EPA-approved ORION chlorine electrode (Model 97-70). Electrode slope was verified monthly and the electrode and meter were calibrated before each use using a 1 part per million (ppm) standard.

After analyzing each batch of samples, any meter drift was documented by reanalyzing the 1 ppa standard. Procedures were in accordance with the " Instruction Manual for Residual Chlorine Electrode, Model 97-70".

The Orion ion Analyzer was used with an' Orion Model 81-02 Ross combination pH electrode to measure pH. The meter and electrode were standardized before each'use with pH buffers 4, 7, and 10. Any meter drift was documented after each use by rereading the values for the standardizing buffers. -

Temperatures were measured with a thermometer accurate to 0.1 0 centigrade and calibrated against a National Bureau of Standards traceable thermometer.

9

i

}

1 i

Salinities were checked using an American Optical 1 Corporation refractometer calibrated with Standard Seawater j obtained.from IAPSO in Surrey, England. ]

i l

2.3.2 S.,ymnlina for Experimental Data )

l In both the demand and flow studies, water samples were taken at the. intake to the test apparatus to determine instantaneous chlorine demand,-and at the discharge from the test apparatus to determine chlorine demand through the test-system. Samples were collected in glass flasks and fixed and analyzed immediately. ;

I In addition, in the demand study, temperature and- j salinity. readings were taken at the intake to the system and temperature was taken at the discharge to determine if there was a temperature change during the 90-minute time of travel through the experimental system.

2.3.3 Pilot Study NPDES Reauired Samolina I

'l The NPDES permit obtained by NAI to discharge from the ]

Chlorine Minimization Pilot Plant into Hampton Harbor d required monitoring of three effluent parameters: flow, pH, and total residual oxidant (TRO). Flow. totals were recorded daily from a calibrated Signet. ACCUM-U-FLO Totalizer (Model MK575). The pH was measured weekly both.in the discharge and the ambient water source. Samples for chlorine- (TRO) '

analysis were taken daily from the discharge. Results of this sampling were summarized and submitted to the EPA monthly on Discharge Monitoring Report forms. Permit limits were not exceeded during the study. j As a check on precision, one TRO-sample per batch, assigned at random, was duplicated and analyzed. In order ;

to validate the TRO analysis, each technician prepared and j analyzed a Performance Evaluation Sample purchased from j Environmental Resources Associates, a firm which supplies and certifies Performance Evaluation / Quality Control samples.

I i

10

i 2.4 BIOLOGICAL DATA l 2.4.1 Samelina After 45 days of exposure, the plexiglass test panels j were removed and placed rough side up into labeled plastic ]

sample containers..For analysis, each panel was placed.on a 4" x 4" grid divided with 100 squares to facilitate.

abundance, percent frequency and percent cover estimates.

Using a microscope with an ocular micrometer, a biologist 1 recorded.the taxa present, and counted and measured the major fouling organisms.

Because of their. small size and occurrence as juveniles, species level ' identification of most panel taxa in this study was difficult or not reasonably possible; therefore family or genus level. classifications were used. ]

The major fouling taxa - included the species' listed below.

Those rarer taxa are listed in Table 4.1-1.

Taxon _Used Soecies Potentially Involved Anomia sp. Anomia simolex'and Heteranomia sauamula jiglanus sp. Balanus balanus,'B.crenatus, B.imorovisus, Semibalanus balanoides Hydroids Tubularia sp., Camoanularia sp.,

Obelia sp.

Mytilidae Mytilus edulis and Modiolus modiolus spat 2.5 DATA ANALYSIS 2.5.1 Data Reduction In general, the biological and physical data were tabulated, means and standard deviations computed, and graphic displays produced.- The chemical data.however, required a more complex treatment. Utilizing the raw TRO .

data and calibration factors, correction factors were applied to the input concentration. The actual input 11

I i

1 1

l concentration was equal to the calculated chlorine input concentration (ppm), which was adjusted for measured (actual) chlorine pump input rate, .and the measured (actual) chlorine stock solution.

Once the input concentration'was adjusted, the instantaneous and final chlorine demands were computed using l the actual input value. All. summary statistics were I computed utilizing programs provided by SAS Institute, Inc. J (SLS, 1985). _

Selected computer-generated values for standard deviation, mean, and correction factors to chlorine input concentrations were computed manually to verify accuracy of the computer program.

]

l l

1 I

1 l

l 4

12 l

l l

,- t 3.0 RESULTS

'3.1 CNTARINE DEMAND STUDY'#1: APRIL 10 - MAY 26. i Chlorine Demand q During the' first study, the actual average' sodium I hypchlorite concentrations input into the test lines . were O.0, 0.50, 0.94, .1.46 and..l.99 ppa .(Table 3.1-1). These concentrations did not exactly match the ' treatment target concentrations 1 due to variability in both ? the pump input rate and the' concentration of sodium hypochlorite stock solution. Variability in these parameters was not regularly monitored in. the start-up ' phase of this test, so. data are presented for. the April May 26' period only, when corrections for' these variables could be regularly applied to target values.

The final '(90-minute) ' demand of the test-seawater increased with increasing. input concentration, reaching 1.14 ppm at 1.99 ppm average input (Table 3.1-1)'. . This demand as a percent of input concentration however, was seen to decrease with increasing input concentration as follows:

AVERAGE AVERAGE. DEMAND AS A PERCENT INPUT CONCENTRATION FINAL DEMAND OF INPUT CONCENTRATION 0.0 --- --

1 0.50 0.48 96% 1 0.94 0.77 82% i l

1.46 1.02- 70%

1.99 1.14 57%

Very little oxidant therefore, remained-at-an input concentration of 0.50 ppm, while 43 % remained at an average dosage-of 1. 9 9 . ppm . The demand was also found to be more variable with increasing input concentration. At the highest input-level, demand varied from 0.52 ppm (29% of an actual input of 1.82 ppm) to 1.98 (88% of an actual input of 2.26 ppm) ; results by date are listed 'in Table 6.1-1 (Appendix).

The demand values from this first study left a total residual oxidant (TRO), ranging from an average of 0.02 to 0.85 ppm for average input' levels of 0.50 to 1.99 ppm, respectively (Table 3.1-2). -Of interest in this case, 13

______ _ - - - - - _ - - - a

TA8LE 3.1-1

. FINAL CHLORINE DEMAND AS A FUNCTION OF INPUT CONCENTRA?!ON.

DEMAND STUDY #1. APRIL 10 - MAY 26. DATA REPORTED FOR APRIL 23 - MAY 26 ONLY.

SEA 8R00K CHLORINE MINIMIZATION STUDY, 1967 ACTUAL .

TREATMENT INPUT CONC FINAL DEMAND I TARGET CONC. CL PPM PPM CL PPM N MEAM S.D. NEAN- S.0. 'j 1

1

'l 0.00 34 0.00 0.00 0.00 0.00 ;

0.50 34 0.50 0.12 0.48 0.12 -J 1.00 34 0.94 0.20 0.77 0.17 1.50 34 1.46 0.10 1.02 0.22 2.00 34 1.99 0.17 1.14 0.32 i

TABLE 3.1-2 .]

FINAL TRO FOR EACH TREATHENT AS A FUNCT!0N OF INPUT CHLORINE CONCENTRATION. ]

DEMAND STUDY #1. APRIL to - MAY 26. DATA REPORTED FOR APRIL 23 - MAY 26 ONLY. l SfA8R00K CHLORINE MINIMIZATION STUDY, 1987.

l 3

ACTUAL TREATMENT INPUT CONC FINAL TR0 TARGET CONC CL PPM PPM CL PPM N MEAM 5.0. MEAN 5.0.

0.00 34 0.00 0.00 0.00 0.00 0.50 34 0.50 0.12 0.02 0.01 1.00 34 0.94 0.20 0.17 0.12 1.50 34 1.46 0.10 0.45 0.20 2.00 34 1.99' O.17 0.85 0.26 i

)

TABLE 3.1-3 ' l PERCENT FINAL TRO VALUES GREATER THAN 0.20 PPM FOR EACH CHLORINE TREATMENT.

OEMAND STUDY #1. APRIL 10 - MAY 26. DATA REPORTED FOR APRIL 23 - MAY 26 ONLY.

SEABROOK CHLORINE MINIMIZATION STUDY, 1987.

TRfATHENT TARGET CONC FINAL 06 SERVAT!0NS >0.20 PPM J CL (PPM) N TRO (PPM) THRESH 0LO NUM8ER PERCENT j l

l 0.00 34 TR0 3 0.20 0 0 0.50 34 TRO > 0.20 0 0 1.00 34 TRO > 0.20 11 32 1.50 34 TRO > 0.20 29 85 2.00 34 TRO > 0.20 34 100 l

a i

14

l are any TRO values >0.2 ppa, since this is.the discharge .I limit set by EPA on Seabrook Station's NPDES Permit. The l final TRO standard deviation indicates the variability around the average TRO (Table 3.1-2). Table-3.1-3 gives the-total number of. observations during the study, and the percent greater than 0.2 ppa. At an. input of 0.5 ppa, no final TRO values greater ' than 0.2. ppa were observed. The percent greater than 0.2 ppa increased from 32% to 100% with increasing average input concentrations of 0.94 to 1.99 ppm.

Biofouling Barnacles, Balanus sp., were the only organisms other than microfouling taxa (bacteria and diatoms) ,. found on' the test. panels during, this first study period (Table ' . 3.1-4 ) .

Settlement occurred. on control and 0.5 ppm and 1.0 ppm treatment level panels. Settlement was effectively.

controlled . at concentrations above the 1. 0 ppm treatment level.~ Table 3.1-4 provides data which indicates that settlement occurred to a greater degree within the initial test barrel than within the final test. barrel for each chlorine treatment level. This is probably due to settlement on the first available surfaces in this location.

Results from these and all subsequent demand studies must be compared through a review of treatments within the initial or final test barrels, and not through a comparison of results between the initial and the final barrels.

Numbers of barnacles on fouling panels (same type) at other sites in the area are listed for a comparison of other fouling data obtained during the same time period.

l Environmental Conditions ,

l Temperature data collected daily in the system showed )

that weekly average temperatures ranged from 7.00 C in the ;

first week to 10.7 C in the last week, indicating the normal !

seasonal warming trend (Table 3.1-5). Salinity taken at ,

high tide (the source of water for these: tests) reflected l the typical spring values. depressed by' spring run-off. l Offshore salinity values (weekly measurements) were-similar- .l to the study's values. Offshore temperatures were somewhat i lower in every case, likely reflecting the fact that the l covered storage pool offered some ' opportunity for warming over the 12-hour residency time. !

i 15 i

d i

TABLE 3.1-4. COUNT OF MAJOR FOULING TAXA IN THE FIRST DEMAND STUDY. SEABROOK CHLORINE MINIMIZATION, 1987.

i FIRST STUDY PERIOD: APRIL 10 - MAY 26 1 MEAN NUMBER / PANEL" TREATMENT INITIAL TEST TANK- FINAL TEST TANK (nom OCl D Balanus so. Balanus so.

1 D 0.0 4 57 (52)a 3 (2) 0.5 4 171 (136) 5 (3) 1.0 4 218 (125) 80 (62) 1.5 4 2 (1) 4 (3) 2.0 4 0 1 (1)

OTHER DATA MEAN NUMBER /PANELa LENGTH OF SITE D Balanus so. MYTILIDAE EXPOSURE Offshore (discharge)c 2 19 1 30 day (May)

Hampton Harbor d 2 732 4 45 day (4/15-5/26)

Storage Poo1 8 2 1 0 45 day (4/15-5/26) a b mean (standard deviation) number of samples c Exposed (-3 m deep); nearshore currents d In tube (low light); tidal currents e In tube (no light); no current 16

q

,. - j I

- l 3.2 CHIoRINE DEMAND STUDY #2: JUNE 27 - AUGUST 7 Chlorine Demand During the second demand study, 'some adjustments ' were made to the target sodium hypochlorite input concentrations.

Actual input concentrations averaged 0.0, O . 7 0 ,'. 0 . 9 3 , 1.19, and 1.41 ppa, which were within 93 to,95 percent of target' values (Table 3'2-1).

. . Variability in' actual input concentrations (as measured by standard deviation)'was quite ,

low, ranging from four to seven percent'over.the six week period. Actual concentrations were . generally' lower than target . values due to reductions in chlorine concentration. <

within the stock solution-(Table 6.2-1, Appendix), as higher air temperatures resulted in greater loss -' due to l volitalization during the second study period. J As in the first demand study,. final. (90 minute) chlorine demand of the test seawater increased with.

increasing input concentration (Table 3.2-1) . Demand as'a percent of input concentration decreased with increased input concentration, ranging from- 93% at 0.70 ppm of input, to 73% at 1.41 ppm input of concentration. These percentage values were quite similar, at the same concentrations, to the percent demand in the first study.- The variability )

(standard deviation) in demand increased'with' increased )

input concentration, as in the first study. ]

)

Final TRO values ranged from 0.05 ppm, at 0.70 ppm input to 0.39 ppm, at 1.41 ppm' input (Table 3.2-2). .The number of final TRO measurements greater- than 0.2 - ppm are listed in Table 312-3. Input concentrations of 0.75 gave no i final TRO excursions above 0.2, while the 1.0 ppm input l level started to show some final values greater than the 0.2 ppm level (25%). Ninety percent.of the readings.were i greater than 0.2 ppm at the 1.50 ppm input concentration. i Biofoulina Other than microfouling on the test panels, mussels l (primarily Mytilus edulis) were the only noticeable .

macrofouling taxon. An average of 629 and 61 individuals !

were found on test panels within. the control line -in the first and last test tanks, respectively (Table 3.2-4). . No

. mussels settled on any of the treatment panels during the 45-day period. On other panels in the study area, more mussels were found of fshore at the discharge panel station and on Hampton' Harbor panels. .While the storage ' pool was continually mixed to discourage settlement 'to the bottom, j i

18 )

i I

1 TA8LE 3.2-1 FINAL CHLORINE DEMAND AS A FUNCTION OF INPUT CONCENTRATION. j l

DEMAND STUDY #2. JUNE 27 - AUGU$T 7.

$EA8R00K CHLORINE MINIMIZATION $TUDY, 1987.

ACTUAL TREATHENT INPUT CONC FINAL DEMAND TARGET CONC CL PPM -PPM CL PPM N MEAN 3.0. HEAN S.0.

l 0.00 20 0.00 0.00 0.00 0.00 '

O.75 20 0.70 0.05 0.65 0.06 1.00 20 0.93 0.06 0.78 0.14 1.25 20 1.19 0.05- 0.91 0.18 i 1.50 20 1.41 0.08 1.03 0.18-

.J l

TABLE 3.2-2 FINAL TRO FOR EACH TREATMENT AS A FUNCTION OF INPUT CHLORINE CONCENTRATION..

DEMAND STUDY #2. JUNE 27 - AUGUST 7.

$EA8R00K CHLOR!NE MINIM!ZAT!ON STUDY,1987.

1 ACTUAL TREATMENT INPUT CONC FINAL TRO TARGET CONC CL PPM - PPM CL PPM N MEAN $.D. HEAN S.D.

l 0.00 20 0.00 0.00 0.00 0.00 .-

4 0.75 20 0.70 0.05 0.05 0.03 1.00 20 0.93 0.06 0.15 0.11 1.25 20 1.19 0.05 0.28 0.15 1.50 20 1.41 0.08 0.39 0.16

)

TA8tt 3.2-3 i

PERCENT FINAL TRO VALUES CREATER THAN 0.20 PPM FOR EACH CHLORINE TREATMENT.

DEMAND STUDY #2. JUNE 27 - AUGUST 7.

SEA 8 ROOK CHLORINE MINIMIZATION STUDY, 1987 TREATMENT TARGET CONC FINAL OBSERVATIONS >0.20 PPM l PERCENT I CL (PPM) N TRO (PPM) THRESHOLO NUMBER 0.00 20 TRO > 0.20 0 0 0.75 20 iRO > 0.20 0 0 1.00 20 TRO > 0.20 5 25 1.25 20 ' TRO > 0.20 12 60 1.50 20 TRO > 0.20 18 90 ;

1 I

l 19 1

1

TABLE 3.2-4. COUNT OF MAJOR FOULING SPECIES-THE SECOND DEMAND STUDY.

SEABROOK CHLORINE MINIMIZATION STUDY, 1987.

SECOND STUDY PERIOD: JUNE 27 - AUGUST 9, 1987 DEMAND STUDY MEAN NUMBER /PANELa MUSSELS (MYTILIDAE)

INITIAL FINAL TREATMENT TEST TANK TEST TANK (com 0C1-) x (S.D.) x (S.D.)

0.00 Count: 629 (338)a 61 (21)

Size: 0.9 mm 0.8 mm 0.75 0 0 1.00 0 0 1.25 0 0 1.50 0 0 OTHER DATA Site nD # Mussels / Panel Excosure Offshore (Discharge)c 2 2734 30 days - (July)

Hampton Harbord 1 2100 45 days; 6/27-8/9 Storage Poole 1 1300 45 days; 6/27-8/9 a Mean (standard deviation) b Number of samples c Exposed (-3 m deep) ; nearshore currents d In tube (low light) ; tidal currents e In tube (no light) ; no current 20

i mussels were still found to set upon panels placed within the pool. Clearly, this test period was significant for j mussel spat settlement. l Environmental Conditions Average ' water temperatures in the system during the second demand study were quite consistent, with weekly averages (of daily measurements) ranging from 16.1 to 17.6 0 C (Table 3.2-5). Single weekly readings in Hampton Harbor and at the offshore intakes were more variable, with the former .

site ranging from 13.4 to 18.00 C and the latter site ranging !

from 15.1 to 18.1 0C. System temperatures were similar to j offshore temperatures.

Salinity values were also consistent, with weekly averages ranging from 29.6 ppt to 30.3 ppt. These values !

Were also similar to Hampton Harbor and offshore salinities I during this period. Overall, temperature and salinity i values were quite similar between the intake waters and the seawater used in the test system.

3.3 FLOW RATE STUDY Chlorine Demand Since the demand tests could only be run at 0.25 fps, a study coincident with the second demand study, was undertaken to test the effects of 0.25, 1.0 and 4.0 fps flow rates. The lowest target chlorine concentration of 0.75 ppm being applied within the demand study, was Shosen for this study. Actual input averaged 0.77 ppm ov6p the six week period (Table 3.3-1). Final demand avert..ged 0.41 ppm, resulting in an average final TRO of 0.36 ppm. This demand was different from the final ( 9 0 -minute.) demand in the second demand study at the 0.75 ppm input, due to the much shorter residency time within the flow ~ study. All raw data from this study are listed in the Table 6.3-1 (Appendix).

Biofoulina Data As with the demand study run concurrently with the flow rate study, mussel spat were the primary settling organisms, other than diatoms and other microorganisms. Mussel spat were recorded only on panels in the lowest flow rate (0.25 fps), averaging 150 per panel (Table 3.3-2); none were recorded at the higher flow rates.

21

- p MR . . . . . .

AA 8 8 8 8 8 8 6 HH 2

/

6

(

c)

Y ES D RE U OK 2 0 0 1 3 3 T HA . . . . . .

- S ST 0 0 0 1 0 1

. FN 3 3 3 3 3 3 D FI N ) O(

A o

- M c E /

O D o D

( N E OR N Y TO 9 5 8 1 8 5

- I T PB . . . . . .

R I MR 9 0 0 1 0 1 O N AA 2 3 3 3 3 3 L I HH H L C A S

D7 N8 ) ) ) ) ) ) )

O9 a . 8 0 4 4 2 5

_ C1 D D . . . . . .

E NY . 0 0 0 0 0 0 S ,

ADS ( ( ( ( ( (

Y MU(

GD ET 6 0 8 1 1 3 NU DSx . . . . . .

- x IT RS U

9 2

0 3

9 2

0 3

DN O

DI ET DA 2 RZ c) 2 OI ES CM RE EI OK 9 1 7 8 6 1 RN HA . . . . . .

I ST 5 8 7 7 7 5 AM FN 1 1 1 1 1 1 T ) FI AE C O(

DN O I (

YR TO E b IL R N NH U OR 4 0 9 0 0 4

% IC T TO . . . . . .

L A PB 5 6 3 7 8 3 AK R

- MR 1 1 1 1 1 1 SO E AA O P HH DR M NB E AA T E ) ) ) ) ) ) )

ES a .

7 3 2 2 2 0 k R D D . . . . . . e U NY . 0 1 2 1 2 2 e T .

ADS ( ( ( ( ( ( w AK MU(

RE ET 2 3 7 5 6 1 r EE DSx . . . . . . e PW 6 7 6 7 7 6 sp M 1 1 1 1 1 1 y EY ae TB dc md nk 7oe

) ) ) e 5 ) 7 4 1 f ,w 2

- 0 1 2 3 ) oe

) 1 / / / 9 dr

. 3 / 7 7 7 / eie 3 / 7 8 gt p K 7 - - - a E E r - - - rhe L E 16 2 31 48 55 '6 egc B W 2 4 1 1 2 1 vin A / / / / / / Aio l

_ T 6 7 7 7 7 8 abc

( ( ( ( ( (

(1, l i :' ,

4-I TABLE.3.3-1 CHIARINE DEMAND AND FINAL TRO (PPM) IN FLOW STUDY SEABROOK OFFSITE CHLORINE MINIMIZATION STUDY JUNE 27, 1987 - AUGUST 7, 1987 N Obs Variable N' Mean Std Dev q i

60 . Actual Input Conc.a. 60 0.77 0.05 j d

Initial Demand 60 0.32 0.14 Final Demand 60 0.41 0.13 Final TRO 60 0.36 0.14 4

a target concentration 0.'75 (ppm) l 1

b l

-i 1

i l

23

3

)

i TABLE 3.3-2. COUNT OF MAJOR FOULING SPECIES IN THE CHLORINE FI4W STUDY. SEABROOK CHI 4RINE MINIMIZATION STUDY, 1987.

I l

FLOW RATE STUDY DATA: JUNE 27 - AUGUST 9, 1987 TREATMENT ;

(0.75 com 0C1-) MYTILIDAE l Flow Rate Count Size (acm) (fos) x (S.D J.A 2 (mm) .

10 0.25 150 (199) 0.5 mm 3 40 1.0 0 0 1 160 4.0 0 0 f:

I aMean (standard deviation) .

)

i 1

24 l i

'l 3.4 CHLORINE DEMAND STUDY #3 ' AUGUST 14 - SEPTEMBER 25 Chlorine Demand The actual ~ average chlorine input concentrations in the third demand study were within 2% of the planned targets; in fact, the two lowest treatments averaged the same as planned (Table 3.4-1).

The final chlorine demand of seawater in this test -

series (Table 3.4-1), ranged from 0.23 ppm (92% of input'at f 0.25 ppm) to 0.70 ppm-(69% of input at-1.02 ppm). Demand ]

levels were lower than those observed for similar input I levels during the two earlier demand' studies. Variability- l (standard deviation) in demand, increased somewhat with I increased input concentration as during earlier' studies.

With the above demand, the final TRO values ranged from

1 0.02 ppm (0.25 ppa input) to 0.32 ppa (1.02 ppm input) (Table 3.4-2). With one exception, the demand was greater than the 0.2 ppm threshold only at concentrations of 0.75 and greater-(Table 3 '. 4 -3 ) . Thirty-seven percent of the final.TRO measurements were greater than 0.2 at 0.75 ppm input; no final TRO values were.above this threshold for 0.75 ppm input in the second test, reflecting less demand during the l August -

September period of the third test. There were'a 1' few dates when demand was quite low during this study. This was the case on August.14 when.the single occurrence of final TRO greater than 0.2 ppm (0.28) occurred at~the 0.50 ppm level.

1 Dipfoulina l During this third test period, only a few ' mussels and Anomia sp., (j ingle shells) , settled on the' test panels (Table 3.4-4). Settlement of mussels was also reduced in.the 1 natural environment during this period when compared with the second study period. Offshore panel counts were'found to be lower by 95% (Table 3.4-4). An2MiA were also observed.on offshore and Hampton Harbor panels, as this marks the period of'their normal occurrence (NAI 1987). Anomia sp. were found >

on panels in the 0.25 ppm and 0.50 ppm treatments; none were found in the control or in treatments greater'than or equal to 0.75 ppm.

Environmental Conditions !

Average weekly water temperatures in the third study were more variable than the second study, ranging from a high of 17.3 C in the first week to a low of 13.9 C in the q l

25 i

7A8LE 3.4-1 FINAL CHLORINE DEMAND AS A FUNCTION OF $NPUT CONCENTRATION.

'OEMAND STUDY #3. AUGUST 14 - SEPTEMBER 25.

SEA 8R00K CHLORINE MINIMIZATION STUDY, 1987.

ACTUAL TREATMENT INPUT CONC FINAL DEMAND TARCET CONC CL PPM PPM CL PPM N MEAN 5.0. MEAN 3.0.

0.00- 19 0.00 0.00 0.00 0.00 0.25 19 0.25 0.02 0.23 0.02 0.50 19 0.50 0.05 0.43 0.06 0.75 19 0.76 0.05 0.57 0.10 1.00 19 1.02 0.07 0.70 0.14 TABLE 3.4-2 FINAL TRO FOR EACH TREATMENT AS A FUNCTION OF INPUT CHLORINE CONCENTRATION. j DEMAND STuoy #3. AUGL'$f 14 - SEPTEMBER 25.

SEA 8 ROOK CHLORINE M!N!MIZATION STUDY, 1987.

ACTUAL I TREATMENT INPUT CONC FINAL TRO TARGET CONC CL PPM PPM J CL PPM N MEM $,0. MEAN S.O.

a j

0.00 19 - 0.00 0.00 0.00 0.00 0.25 19 0.25 0.02 0.02 0.01 )

0.50 19 0.50 0.03 0.07 0.05 )

0.75 19 0.76 0.05 0.19 0.09 i 1.00 19 ,1,02 0.07 0.32 0.13

]

l i

TA8t0 3.4-3 j PERCENT FINAL TRO VALUES GREATER TMN 0.20 PPM FOR EACH CHLORINE TREATMENT.

OENANO STUDY #3. AUGUST 14 - SEPTEMBER 25.

SEA 8R00K CHLORINE MINIMIZATION STUDY, 1987.

TREATHENT TARGET CONC FINAL OBSERVATIONS >0.20 PPM CL (PPM) N TR0 (PPM) THRESHOLD . NUMBER PERCENT 0.00 19 TRO > 0.20 0 0 0.25 19 TR0 > 0.20 0 0 0.50 19 TR0 > 0.20 1 5 0.75 19 TR0 > 0.20 7 37 l

l 1.00 19 TR0 > 0.20 16 84 !

26-

, +

TABLE 3.4-4. COUNT ' O F- MAJOR FOULING ' SPECIES IN THIRD DEMAND STUDY. SEABROOK CHI 4RINE MINIMIZATION STUDY, 1987. .

i THIRD. STUDY PERIOD:'- AUGUST 14 - SEPTEMBER 28 DEMAND STUDY MEAN NUMBER / PANEL" TREATMENT INITIAL TEST! TANK. FINAL TEST. TANK (com ocl~1 b MYTILIDAE ANOMIA MYTILIDAE ANOMIA D

0.0 6 <1 0 0 0 0.25 6 <1 0 0- 3(3)a 0.50' 6 0 0 0 <1 0.75 6 0 0 0 0 1.00 6 0 0 0 0 OTHER DATA MEAN NUMBER / PANEL .,

SilA D Mytilidae Anomin Excosure Offshore (Discharge)c 2 149 49 30 days q (Sept) ._

Hampton Harbord 2 15 66 45" days (8/14- 9/28)

Storage Pool" 2 0 3 45 days )

(8/14-9/28) j 8

b mean (standard deviation)

Number of samples I c

d Exposed (-3 m deep); nearshore currents In tube (low light); tidal currents'-

In tube (no light) ; no current -

l 1

i 27 -

1

1 v

l third week (Table - 3.4-5) ; average temperature in the' system actual increased from the third - to the 'fifth week. These ;

temperature' fluctuations were reflectedLin similar changes )

in Hampton Harbor and offshore-(intake site). . Temperatures i were somewhat higher in the system, as a . result of solar )

heating'of the storago pool. 1 Average salinity values in the test system were very consistent, with a maximum ^ range of 0.9. ppt (Table 3.4-5).

Salinity measurements offshore were also quite similar, although they averaged 0.7 ppt higher overall. )

l l

1 3.5 CHIDRINE DEMAND STUDY #4; SEPTEMBER 28 - NOVEMBER 9 i t Chlorine Demand The target chlorine concentrations for this demand study were maintained from"the third demand study. The actual average chlorine' input concentrations in the fourth demand study were within 0.02 ppm (most within 0.01 ppm) . of -,

the targeted treatments (Table 3.5-1). The greatest !

relative variability in input level. occurred at the 0.51'pp.u. H treatment with a standard deviation of 0.04 ppm; less than an 8% variability in input concentration.

The demand of seawater in the system ranged from 0.24 .i ppm (92% of input at 0.26 ppm) to 0.58 ppm (57% of input at i 1.02 ppm) (Table 3. 5-1) .. The latter demand ' was ~ about 12% '

lower than that observed in the third study for the same input. Variability (standard deviation) -in demand was .j similar to the third study.

Final TRO values ranged from .02 ppm to 0.44 ppm (Table 3.5-2). As in the third study, with one exception only treatments above 0.50 ppm input yielded final TRO values greater than the 0.2 ppm threshold; the number of. readings

>0.2 ppm at 0.75 and 1.0 ppm input were-higher in the fourth ]

I study than in the third (Table 3.5-3). As in the third l l

study,' there were also a few dates with'relatively low l demand. Such was the case'on November 9 when TRO at the 0.50 '

ppm input level was above 0.20 ppm threshold (.21 ppm).

However, the actual input level on that dat's was 0.54 ppm; .-

if a 0.50 ppa actual input level had been maintained,.the final TRO would theoretically.have been below'O.20 ppm. ,

o 1

28

HH 8 8 8 8 8 8 4

1

/

8

(

c)

Y ES D RE 3 6 5 9 3 4 U OK . . . . . .

T HA 1 1 1 0 1 1 S ST 3 3 3 3 3 3 FN D FI N ) O(

A o M o E f D o b

( N E OR 2 5 4 3 4 5 N Y TO . . . . . .

I T PB 1 1 1 1 0 0 R I MR 3 3 3 3 3 3 D N AA I HH I

H L C .

A 7 S D8 ) ) ) ) ) )

R9 ) 4 4 4 5 9 5 I1 a . . . . . . .

H D D 1 0 0 0 0 0 T , NY . ( ( ( ( ( (

Y ADS GD MU( 1 4 9 5 1 0 NU ET . . . . . .

IT DSx 0 0 0 0 0 0

- RS 3 3 3 3 3 3 U

DN O

DI ET DA c) 9 RZ ES 2 OI RE CM OK EI HA 0 0 4 2 7 8 RN ST . . . . . .

I FN 6 1 1 2 5 3 AM FI 1 1 1 1 1 1 T ) O(

AE C DN O I (

YR TO E D IL R N NH U OR 3 6 6 0 8 5 IC T TO . . . . . .

L A PB 6 2 1 4 4 5 AK R MR 1 1 1 1 1 1 SO E AA O P HH DR M NB E AA T E ) ) ) ) ) )

ES ) 6 7 5 3 7 6 k R a . . . . . . . e U D D 0 1 1 1 0 0 e T .

NY . ( ( ( ( ( ( w AK ADS RE MU( 3 3 9 5 1 7 r EE ET . . . . . . e PW DSx 7 4 3 4 6 4 sp M 1 1 1 1 1 1 y EY ae TB dc nk 7oe 5

. ) ) ) e e

9 ) ) 9 7 f ,w 6

4

- )

1 2 5 2 1 2 oe

/ / 1 / / dr 2 8 9 / 9 9 eie 3 / 9 gt p K 8 - - - - a E E - - rhe L E 14 22 30 4 53 60 egc B W 1 2 3 6 1 2 vin A / / / / / / Alio T 8 8 8 9 9 9 abc

( ( ( ( ( (

4 .

TASLE 3.5-1 FINAL CHLORINE DEMNO AS A FUNCT50N OF INPUT CONCENTRAff 0N.

. 00%NO STUDY #4 SEPTDGER 28 - NOVEMBER 11.

SEA 8R00K CHLORINE MIN!Mt!ATION STUDY, 1987.

ACTUAL J

TREATMENT INPUT CONC FINAL DEMAND

PPM !

TARGET CONC CL PPM CL PPM N MEAN 3.0. MEAN 5.0.

0.00 18 0.00 0.00 0.00 0.00 0.25 18 0.26 0.01 0.24 0.01 0.50 18 0.51 0.04 0.43 0.03 0.75 18 0.76 0.03 0.50 0.11 1.00 to 1.02 0.04 0.58 0.17 i

TABLE 3.5-2 q

FINAL TRO FOR EACH TREATMENT AS A FUNCTION OF INPUT CHLORINE CONCENTRATION.

I DEMNO STUDY #4. SEPTEMBER 28 - NOVEleER 11.

SEABROOK CHLOR!hE MINIM!ZATION STUDY, 198T.

ACTUAL TREATMENT INPUT CONC FINAL TRO TARGET CONC CL'FPM PPM j CL PPM N MEAN 3.0. MEAN 5.0.

I 0.00 18 0.00 0.00 0.00 0.00 0.25 18 0.26 0.01 0.02 0.01.

0.50 18 0.51 0.04 0.09 0.05 i 0.75 18 0.76 0.03 0.26 0.11' l 1.00 18 1.02 0.04 0.44 0.16 i

TABLE L5-3 PERCENT FINAL TRO VALUES GREATER THAN 0.20 PPM FOR EACH CHLORINE TREATMENT.

DEMAND STUDY #4. SEPTEMBER 28 - NOVDeER 11.

SEA 8R00K CHLOR!NE MINIMIZATION STUDY, 1987 TRfATMENT TARGET CONC FINAL OBSERVATIONS >0.20 PPM CL (PPM) N TRO (PPM) THRESH 0LO NUMBER PERCENT 0.00 18' TRO > 0.20 0 0 0.25 18 TRO > 0.20 0 0 0.50 18 TRO > 0.20 1 6 0.75 18 TRO > 0.20 12 67 1.00 18 TR0 > 0.20 15 100 30

w Biofouling During the fourth study ' period, 50% of. the roughened plexiglass panels were maintained from the previous study to determine the effects of.a 90-day exposure period. During.

this period, there were-three main fouling.macroinvertebrate taxa: mussels, jingle shells (Anomia sp.) and hydroids (Table 3.5-4, 3.5-5). The degree of settlements was generally similar between the 45-day'and 90-day. periods !

(encompassing both the third and. fourth tests) ,- although I there were a few more Mytilidae . . spat L and greater hydroid-cover'in some of the test.levelsLafter 90 days of exposure.

The most notable fouling. taxon during these two tests were hydroids', a" stalked cnidarianLwhich, within.the natural environment, has been ' known - to cover up - to 100% of.

visible surfaces during;the late summer and fall -

(see offshore panel data ' in ' Table - 3.5-4) . :This taxon was-more-abundant on panels in the final test tank than in.the first, and noticeably abundant on the : .0. :2 5 ppa and 0.75 ppm treatments. Hydroids were almost totally lacking from settlement.at the 0.50 ppa treatment.. level. All three taxa were ' also -found to occur: in low numbers when compared to data obtained from test' panels deployed offshore .

Environmental Conditions Average water temperatures in the ~ test' system declined from a maximum of 14.2 C'during the first' week to a minimum 0

of 8.6 C for tho'last week-(Table 3.5-6). .This natural seasonal cooling was reflected in data collected in'Hampton Harbor and at the offshore site as well. Salinities were- '

very constant ' over this study period, the weekly averages not differing by more than 0. 5 ' ppt - (Tabl~e 3.5-6).

Salinities in the system were somewhat (1.2 to.'1.9 ppt) lower than' salinities measured offshore at the intakes.

31' ,

i

l .

I TABLE 3.5-4. COUNT OR PERCENT COVER OF MAJOR FOULING TAXA IN FOURTH DEMAND STUDY FOR 45 DAY EXPOSURE PERIOD.

SEABROOK CHLORINE MINIMIZATION STUDY, 1987.

Fourth Study Period Sept 28 - November 11 INITIAL TEST TANK MEAN NUMBER /PANELa TREATMENT l b MYTILIDAE ANOMIA HYDROIDS (com OCl~1 D a <1 2% c 0.0 3 9 (6) 0.25 3 <1 0 <1%

0.50 3 2 (2) 1 (1) 0 0.75 3 1 (2) 0 25%

1.00 3 0 0 0 FINAL TEST TANK l MEAN NUMBER / PANEL {

TREATMENT (com OCl 1 D MYTILIDAE ANOMIA HYDROIDS j l

0.0 3 0 <1 1% )

0.25 3 0 0 59% !

0.50 3 <1 0 0 0.75 3 <1 0 33%

1.00 3 0 0 0 l OTHER DATA NUMBER / PANEL j

Site D MYTILIDAE ANOMIA HYDROID EXPOSURE Offshore (Discharge)d 2 91 4 100% 30 days Hampton Harbor e 1 30 55 0% 45 days Storage Pool f 1 30 42 17% 45 days a

b mean (standard deviation)

Number of samples c Percent of visible surface covered d Exposed (-3 m deep); nearshore currents e In tube (low light); tidal currents f

In tube (no light); no current 32 I

-l 1

l TABLE 3.5-5. COUNT OR PERCENT COVER OF-MAJOR FOULING TAXA IN j FOURTH DEMAND STUDY FOR 90 DAY EXPOSURE PERIOD.

d SEABROOK CHLORINE MINIMIZATION STUDY, 1987.

Study Period August 14 - November 11 INITIAL TEST TANK L a- 1 MEAN NUMBER / PANEL TREATMENT ]

-(oom OCl~1 nD MYTILIDAE ANOMIA HYDROIDS >

0.0 3 22 (3)a <1 1% C 0.25 3 <1 0 34%

0.50 3 3 (4) '1

< 0 '

0.75 3 3 (3) 1 (1) 25%'

1.00 3 <1 0 17%

~

ETNAL TEST TANK MEAN NUMBER / PANEL TREATMENT ,

(com OCl 1 D MYTILIDAE ANOMIA' HYDROIDS 0.0 3 <1 -< 1 0 0.25 3 0 0 73%

0.50 3 3 (2) 0 6%' )

0.75 3 <1 0 25%

1.00 3 0 0 0 ] 4 a

b mean (standard deviation) l '

Number of samples c Percent of visible surface cov' ered j

I 33 I

lljj{' ;

1l ,

) c 1 N

~1 OR x

/ TO 0 0 0 5 5 .'0 1 H PB 0 0 2 0 0 9 1 p MR AA 8 8 8 8 8 7

- HH 8 _

2

/

9

(

c)

Y ES D RE 4 5 3 0 8 J

1 OK . .

T HA 1 A 1 1 2 1 S ST 3 N 3 3 3 3 FN D FI N O(

A M

E )

D o o D E / N - 3 9 4 4 2 8 N o OR . . .

I ( TO 1 0 1 1 0 1 R PB 3 3 3 3 3 3 O Y MR L T AA H I HH C N

. I H7 L ) ) ) ) ) )

T8 A 7 6 6 2 5 9 R9 S ) . . . .

U1 a . 0 0 0 0 0 0 O D ( ( ( ( ( (

F GD NU IT Y

, NY ADS MU(

ET DSx D.

1 0

3 9

9 2

1 0

3 1

0 3

1 0

3 4

3 0

RS U

DN O

DI ET 4 DA c) 3 RZ ES OI RE CM OK 2 9 1 3 7 EI HA . . .

RN ST 3 A 0 2 0 9 I FN 1 N 1 1 1 AM ) FI T' C O(

AE O DN (

I YR E D TO R N -

IL U OR 8 9 4 1 0 3 NH T TO . . . .

IC A PB 4 2 1 2 1 0 L R MR 1 1 1 1 1 1 AK E AA SO P HH O M DR E NB T -

AA ) ) ) ) )

E 3 3 9 0 9 ) k ES ) . . . . 0 e _

R a . 1 1 0 1 0 . e U D ( ( ( ( ( 1 w _

T .

NY D. (

AK ADS 2 3 0 9 1 .r _

RE MU( . . . . . 6. e EE ET 4 2 1 1 0 . sp PW DSx 1 1 1 1 1 8 y M ae EY .

dc e TB ) ) .nkl

) 8 5 ) ) 7oeb _

) 1 1 2 1 1 ea

. 4 1 / / / 1 f ,wl 5 / / 0 0 1 / oe i 5

3

. K E

0 1

1 1

1 dra eiev gt p a a

=

E 2 - 9 6 r h e t.

E W 18 25 31 41 52 62 a g c o.

L 2 / / / / / vinN B / 0 0 0 0 1 2 Ho:

A 9 1 1 1 1 1 abcA T ( ( ( ( ( ( N i '

1 4.O DISCUSSION 4.J CHLORINE DEMAND A review of the chlorine demand J at the 1.0' ppm: input.

level over the four.' study. periods (April 23'through November i 11) reveals that the seawater's ' average demand was 'similar L during the first two studies, dropped a little in. the third l study, and dropped again in the final test (Figure 4.1-1)'.

The average final TRO'in.the' test seawater varied as a...

function of input concentration and the season (Figura 4.1 -

2). 'For example, at 1.0 ppa input, the average final; TRO' l 'was less'than 0.2 ppa in the spring study,-but was twice as high (0.4 ppm) in _ the fall- ' study due ^ to decreased demand."

This seasonally decreasing demand and increasing TRO-is more-evident when all . data. are plotted together --(Figure 4.1-3) .~

During the first two study periods, seasonal changes'in f- final TRO were not a factor _with respect to tho'O.2 ppm threshold at 0.5-ppa input, but;were-at the 0.75 ppm level.

During the second study-(and probably'the first-as-inferred by -interpolation) the final TRO 'was- well below 0.2 ppm at 0.75 ppm input. By the late summer and fall studies, the average TRO'was near or above.0.2 ppm; in fact, 37 and'67 percent of the final TRO readings during these two studies, respectively, were above this level (Figure 4.1-4).

l 4.2 BIOFOULING Controlled Tests While a number of taxa were recorded on the roughened '

plexiglass panels in the test system (Table 4.1-1), 'only four taxa occurred with any abundance. The degree'of fouling depended on the season, the level of treatment, and the test tank. Panels in the first test tank in each'line had more fouling than those in the final tank (Tables'4.1-2 and 4.1-3).

Barnacles (Balanus/Samibalanus sp.)' occurred during the first study only, coincident with the natural spring recruitment of these species. Settlement occurred from the control (no treatment) up to'the 1.0 ppm input level;-

settlement dropped sharply after that concentration. At the 1.0 ppm level, panels' in _ the final tank' (after. 90-minute demand) were exposed'to an average of at least 0.17 ppm (final) TRO over this first study period. The increased ')

concentrations of chlorine was observed to reduce the j

" micro" fouling (diatoms, etc.) on the test panels.

35

0.7 -

i 0.6 -

n 0.5 - r A g Q

3 r e As s 2

& 0.4 - h;y ~ 7 g~ Z 3 FE +i4

r. m .

h - ~.

x,~.a

. 7 .. g

. 0.3- bs5 m ' -; : ?l , '1 0.2 -

0.1 -

Matidd l g$$ D b 5Si !

O.0-

$29BttF i

.Eh h l b '

1 2 3 4 TEST 0.8 -

0.7 , l , \

0.6- -

r a E

0.5- er Di f _

0.4 -

. 1 0.3 O.75 ppm g ,

I 0.2- W

=- ,

f +F:.. . .

g pg g .; ,c -

0.1 - a w_ -

m 4$; l EPM

" ' ' ~ # "MM* ~ W"'y*G;W

0.0 .

1 2 3 4 TEST 1.0 -

4 0.8- r a/ .

J

' ' ^

5$ANk ggnb *

[ ;snB

@e$pf*' e 0.e - :*

3 a

5

$$@6 sR$N

[e E i-

]$$ff$

g 04-

g$ j%EMM d$p 1.0 ppm o -

i 1h P@?m$

M g

M@f@$

ea 3pM E4fd ra w 0.2 - y .

g.a gwmii

% ~ an 19s5%

0.0

ik t . fyw Sn hf Ib 1 2 3 4 TEST Figure 4.1-1 Averhge (and standard deviation) chlorine demand for selected treatment levels across each demand study.

Seabrook Chlorine Minimization Study, 1987.

36 I- - '

J

i l}

Tcst #2 (6/26 8/9)

Test #1 (4/10 - 5/26) 1.3-1.3-1.2 2 1.2 .

" 1.1 -

1.1 -

1.0 - '

1.0 -

0.g2 E 0.9{

O.8{

g 0.8 -

0.7-0.7- "

0.6 2 ;

0.6- . "

8 0.5 -

d 0.5 2 l 0.4 - ji 0.4 -

0.3 ..

0.3 - ,, j( "

0.2 0.2' .

0.1 0.1k 0.0 , , , , , !

0.0 . . . , , ,

0.5 1.0 1.5 2.0 2.5 0.0 ~

0.0 0.5 1.0 1.5 2.0 2.5 INPUT CONCENTRATION (ppm)

INPUT CONCENTRATION (ppm) i 1

1 Test #3 (8/14 - 9/27) 1.3 - Test #4 (9/28 - 11/11) 1.3- '

'S 1.2-1.1-

~

I'l 1 1.0 -

1.0 - '

09:

f

- 0.9 -

0.8-f 0.8 ;

o 07-o ' O.7 - ~

$ 0.6 - .

@ 0.0- '

N 0.5-

$ 0.5- '

[

k 0.4 - ,.

0.4{ 1 0.3 - ..

O.3-0.2 ..

0.2 .

0.1 - 0.1-0.0 , , , , , , 0.0 . . . , , , ,

0.0 0.5 1.0 1.5 2.0 2.5 0.0 0.5 1.0 1.5 2.0 2.5 :

INPUT CONCENTRATION (ppm) INPUT CONCENTRATION (ppm)

Figure 4.1-2. Final TRO as a function of Chlorine input concentration for each demand test. Seabrook Chlorine Minimization Study, 1984.

37 ,

i

, FinalTRO AllTests' 1.3 -

1.2 -

1.1-1,0 - + TEST 1

+ TEST 2

+ TEST 3 0.9 - + TEST 4

. I ;

i 0.8 -

l 0.7 -

O '

N 0.6 - "

i E 0.5 - .

1 I . /

0.4 - ,

l i

0.3 - .

0.2 j/[) i .

.. l 7

0.1- /

O.0 .

0.00 0.25 0.50 0.75 1.00 1.25 1,50 1.75 2.00 2.25 2.50 I

INPUT CONCENTRATION (ppm) 8 l

1 Figure 4.1-3. Final TRO (mean and standard deviation) as a function j of Chlorine input concentration across all tests. i S.eabrook Chlorine Minimi,zation Study, 1987. j

- 38 4

1

'1 i

Percent Final TFIO > 0.2 ppm j

100 -

90 -

80 -

70 -

60 -

s E TEST 1 (n=35) 50 E TEGY 2 (n=20)

O E TEST S(n=16) l -

E3 TEST 4 (n=16) 40 -

30 -

20 -

10 -

0 . . .

0.0 0.25 0.50 0.75 1.00 1.25 1.50 2.00 TREATMENT (Cl ppm) h old to s dy roo h r ne ni ation Study, 1987.

39

jl ,

l' i1I1i>

~

S T

N E X X X X X X X_

T T

A 4E 8R y T eLO X X X X X X X X X nR ST

_ N s

_ O

_ C S

r f

B 1 X X X T

A 3E 8R

. Y T

Y 2 e.

1 L X TO X X 1

T SRT S f I

s l C O

A ._

M _

E _

D .

E I

R S A T _

I N -

M X C E .

T M A C E A

E 2R 8T L N Y I 2LO X X X X X X 1

S78 I

TR Sr f 9

E1 A

O C

B P .

Y TD N

EnS D

LN s S e TO T TI N i r

ET E SA M X X o Z T g NI A e OM I

"!sRE t a

DN T c EI Y ._

DM c R mL i i _

OE TO X X X X m o

CN SRr ._

EI s n _

RR f e t o _

D n x AID e at .

C .

XN m ._

AC t -

T a f e o .

FN On t r

n a o TB d n

i SA t IE a a LS n s s a d e l

. o t p 1 p a x -

- e d e 1 p s o r r 4 e . eh c o o a . p . a f f -

E . d p . s t p d t L . a p i s p n s l c s s B A . p . r s r s . a i o n d d A X e p s p e a s p r m si a c i a

o oh T A a s s A s f a l u m s oh l d i v h

'pi a N T s d s d X i l u l u e b o t i t t O m i la u i A s n l n l i a p h r c an v e e X t o i m o T lu a et a y d l o y o l MM A

0 0 t i m a r m p r i u i t r h p u a T 9 ia 1

4 o l d E o r a m t l g l a i p r c v e e G D M y

A n a B

y H

R s A P F o i H

a C B o

gM o i C

l P

p S m a a A M t i

B e e s s C R *

&O

TABLE 4.1-2. -BIOFOULING ON TEST PANELS (INITIAL) ACROSS ALL STUDIES IN 1987. SEABROOK CHLORINE MINIMIZATION STUDY, 1987. ,

INITIAL TEST TANK PANELS MEAN NUMBER OF INDIVIDUALS PER PANEL OCl" CONC. (ppm)

TAXA / DEMAND STUDY -0.0 0.25 0.5 0.75 1.' O 1.25 1.50 2.0 Balanus sp.

171 218

1 Apr-May 57 - - -

2 0

2 Jun-Aug 0 - -

0 0 0 0 -

3 Aug-Sep 0 0 0- 0 0 - - -

4 Sep-Nov (45 d) 0 0 0 0 0 - - -

4 Aug-Nov (90 d) 0 0 0 0 0 - - -

i Mytilidae !

i

1 Apr-May 0 -

0 -

0 0

2 Jun-Aug 629 - - 0 0 0 0 -

3 Aug-Sep <1 <1 0 0 0 - - -

4 Sep-Nov (45 d) 9 <1 2 l' O - - -

4 Aug-Nov .(90 d) 22 <1 3 3 <1 - - -

Anomia sp. l i

1 Apr-May 0 -

0 - 0 -

0 0

2 Jun-Aug O.

- - 0 0 0 0 -

3 Aug-Sep 0 0 0 0 0 - - -

4 Sep-Nov (45 d) <1 0 1 0 0 - - -

4 Aug-Nov (90 d) <1 0 <1 1 0 - - -

Hydroids (% Cover) ;

1 Apr-May 0 -

0 -

0 0

2 Jun-Aug 0 - -

0 0 0 0 -

3 Aug-Sep 0 0 0 0 0 - - -

4 Sep-Nov (45 d)- 2 <1 0 25 0 - - -

4 Aug-Nov (90 d) 1 34 0 25 17 - - -

l i

I I

41

TABLE 4.1-3. BIOFOULING ON TEST PANELS (FINAL) ACROSS ALL I STUDIES IN 1987. SEABROOK CHLORINE MINIMIZATION STUDY, 1987.

1 FINAL TEST TANK PANELS MEAN NUMBER OF INDIVIDUALS PER PANEL OC1~ CONC. (ppm)

TAXA / DEMAND STUDY 0.0 0.25 0.5 0.75 1.0 1.25 1.50 2.0 I

Balanus sp.

1 Apr-May 3 -

5 -

80 -

4 1 l

2 Jun-Aug

0 - -

0 0 0 0 -

I

3 Aug-Sep O O O O O - - - l l # 4 Sep-Nov (45 d) 0 0 0 0 0 - - -

4 Sep-Nov (90 d) 0 0 0 0 0 - - -

l Mytilidae l l

1 Apr-May 0 -

0 -

0 0

2 Jun-Aug 61 - -

0 0 0 0 -

- *. # 3 Aug-Sep 0 0 0 0 0 - - -

4 Sep-Nov (45 d) 0 1 <1 <1 0 - - -

4 Sep-Nov (90 d) <1 <1 3 0 0 - - -

Anomia sp.

1 Apr-May 0 -

0 -

0- 0

2 Jun-Aug 0 - -

0 0 0 0 -

3 Aug-Sep 0 3 <1 0 0 - - -

4 Sep-Nov (45 d) <1 0 0 0 0 - - -

4 Sep-Nov (90 d) <1 0 0 0 0 - - -

Hydroids (% Cover)

1 Apr-May 0 -

0 -

0 0

2 Jun-Aug 0 - -

0 0 0 0 - !

3 Aug-Sep 0 0 0 0 0 - - -

4 Sep-Nov (45 d) 1 59 0 33 0 - - -

4 Sep-Nov (90 d) 0 73 6 25 0 - - -

i 42 -

t Mussel spat ( Mytilidae, since. Modiolus'mediolus may-be present along with Mytilus adulis)'were most abundant on.

test. panels during the second study' period (June 26 - Augustl

9) 'at i the same time their settlement: peak.was reache_d- on offshore surfaceLpanels.- Although;much lower, the next most abundant. period for settlement :was during the ' fourth study;.

secondary E recruitment -- periods have also been observed in baseline studies in the area (NAI,1987). ~When mussel spat were most' abundant, the lowest chlorine treatment: level tested was . 0.75 ppa and .no spat settled on. tank panels at that concentration, or above; final:TRO at the panels in the.

last tank' were in the - 0.05 range:at 0.75. ppm input. The flow rate study, however, did show'some mussel. settlement at the 0.75 ppm dosage level at the same' flow' rate (0.25 fps),

as the demand study. However, no mussel settlement' occurred at the higher flow rates that simulated the ' Station's Circulating Water System ' flows. It may be ' that the plug flow of the flow rate study' provided . a better environment-

'for settlement than the turbulent gravity flow of the demand-study, but it is unclear as to why'this would be so. . During the fourth study, some did settle at the 0.75 ppm level; however, most were restricted.to lower or no treatment levels. The panels were exposed to an average . final _ . TRO level of at least 0.23 ppm at 0.75 ppm input, and less.than 0.10 ppm at 0.50 input ppm-level. q The jingle shell (Anomia sp.) occurred during the third ,I and fourth study periods, but were not abundant at any -l treatment level. Their settlement on natural fouling 'l surfaces during the late summer / fall period however, still 1 I

leaves a strong possib.ility of the species ' " conditioning"'

surfaces for further settlement. This species was not observed in treatment input levels above 0.5 ppm.

The other taxa that were abundant fouling organisms ~

during this study were hydroids (Tables 4.1-2, 4.1-3).

Tubularia sp. was .the dominant species and only occurred during the fall study period. This species was observed on I test panels within the control, 0.25 ppm, and 0.75 ppm H treatment levels. Very little was . found on control panels; it wasinot found on Hampton Harbor panels but was abundant l on offshore panels. While this species ' is abundant only j temporarily (the majority is crowded.out, eaten, or sloughed l off over time), it forms a " furry" mat which traps other fouling species, particularly mussels which may then become established.

s 43 +

s Mussel spat ( Mytilidae, since Modiolus mediolus may be present alongLwith Hytilus edulis) were most abundant-on test -panels during the second study period (June 26 - August

9) at the same time their settlement. peak was reached on offshore surface panels. .Although much lower,.the next most

-abundant period ~.for. settlement was during the fourth study; secondary recruitment ' periods have also been observed 'in baseline studies in the; area (NAI,1987). When mussel spat .I were most abundant, the-' lowest; chlorine treatment level tested was 0.75 ppa and no spat settled.on tank panels at:

1 that concentration,.or above;-final TRO at the panels in the -]

last tank were in the 0. 05 - range at 0.75-ppm input. The' ]

flow rate study, however, did show some mussel settlement at the 0.75 ppa dosage level at the same.' flow. rate (0.25 fps) as the demand study. However, no mussel settlement. occurred at the higher flow' rates 'that simulated the ' Station.'s circulating Water System flows. It may be that the plug

']a flow of the . flow rate study provided a better environment l for settlement than the turbulent gravity flow of.the demand !

i study, but it is unclear'as.:to'why.this would be so. During the fourth study, some did settle at the 0.75sppm-' level; however, most were restricted to ' lower';or.no treatment levels. The panels were exposed to an . average . final TRO-j level of at least 0.23' ppm at 0.75 ppm input,'and.less tha'n 0.10 ppm at 0.50 input ppm level. 1 1

The jingle shell (Anomia sp.) occurred during the' third )

and fourth study periods, but were not abundant at any-treatment level. Their settlement -on- natural fouling surfaces during the. late summer / fall : period however,. still j leaves a strong possib.ility of the species " conditioning" surfaces for further settlement. This species was not observed in treatment input levels above 0.5 ppm.- ,

The other taxa that were abundant fouling organisms during this study were hydroids (Tables 4.1-2, 4.1-3).

Tubularia sp. was the dominant : species and only ' occurred during the fall study period. This species.was observed ~on test panels within the control, 0.25 ppm, and 0.75' ppm treatment levels. Very little was found on control panels;-

it wasinot found on Hampton Harbor panels but was abundant ;

on offshore panels. While ' this species is abundant only '

temporarily-(the majority is crowded out,. eaten, or sloughed off over time), it forms a " furry" mat which ' traps 1 other fouling species, particularly mussels which may then become established, i

i 43 -

Additional Foulina Data At the end of the fourth study it was observed that.the-short, clear plastic-pipes that connect the test tanks were fouled with mussels. Counts of. mussels per unit length lof

. pipe were made, to identify treatment. differences. The period of exposure was at'leastL90-days, the period of the- ;

last-two' tests; however, this was an uncontrolled test, '

since the settlement period was not. fixed.

From ' the -results of these tuba counts, it.was cl'ea r ' 1 '

that mussels were very abundant and substantially: larger in the untreated line (Figure 4.1-5). There were'some mussels i I

in the lines up to the 0.75 pga input level, but they.-were extremely small (0.3-0.5 mm) compared' with ' the untreated line (averaging almost.7.0 mm). Anomia-sp. were alsoffound 1 in these' lines and were noticeably more abundant'in the 0.25- '

ppa input level. Thus it appears that these-. major: fouling.

taxa could . survive for at least 90 days at these chlorine input levels, but would attain no appreciable size.-

l Offshore Fouline Data I Densities of fouling species on- offshore subsurface-panels (30 day settlement) were tabulated to show species settlement periods with respect to chlorine demandftest periods (Table : 4.1-4) . These results show.the seasonality of the dominant fouling, species and the. success in. timing.of i the demand studies to coincide with the major settlement i periods. It also shows that the studies covered the; major portion of the active . biological year with respect.to settlement periods for these taxa.-

i l

4.3 M DATA Temperature and Salinity Data Monitoring of the test system for water temperature and salinity showed- the seasonal' dif f erences that'were y anticipated over the test -period (Figure 4.1-6).

Temperatures were increasing in the spring (7 0 to 11 0C),

reached a maximum at the beginning of the third study (17 0C) 0 Salinity and ~ decreased through the fourth study (to 9 C) .

showed the same trend through the first two studies, due.to increased rainfall and runoff during that - period,_and then generally stayed above 30 ppt through the third and fourth studies.

I 44

l 1

1 i

1500 -

Abundance l 1250 -

1000 -

E MYTILIOS E ANOM1A l k

' 750 -

500 -

250 -

0 i ,

0.0 0.25 0.50 0.75 1.00 CONCENTRATION (ppm) l l

i i

1 10 -

Length l 8-E 6-

5. I iE l I

O 4-

"i l

2- l O.

, , i .....1 0.0 0.25 0.50 0.75 1.00 CONCENTRATION (ppm)

Figure 4.1-5. Abundance and mean length (and standard deviation) of major fouling species in test discharge lines (clear tubing) after 90+ days exposure. Seabrook Chlorine MinitrJ.zation Study, 1987.

45

T TABLE 4.1-4. MAJOR FOULING SPECIES ON OFFSHORE (DISCHARGE)-

SUB-SURFACE PANELS. SEABROOK CHLORINE MINIMIZATION STUDY, 1987.

E COUNT / PANEL MONTH (1987) j SPECIES JAN FEB MAR APR- MAY- JUN Mytilidae 20 24 13 0 1 1 !

Balanus sp. 0 0 0 35 19 32 ;

l Anomia sp. 0 0 1 'O O O Tubularia sp.a 0 0 0 0 0 0 ]

l j

Demand Study # I----#1-----I l (4/10 - 5/26) .!

l l I 1

SPECIES JUL AUG SEP OCT NOV -DEC l

Mytilidae 2734 , 59 149 91 90 Balanus sp. 2 0 0 0 0 l

Anomia sp. 4 0 49 4 2 Tubularia sp 8 63% 100% 100% 59%

Demand Study # I------#2------I I------#3----I-----#4------I (6/26 - 8/9) (8/14 - 9/26) (9/28 - 11/11) a Percent of visible surface covered 46 i

5 0 5 0 5 0 5 0 5 0 0 0 9 8 8 7 7

. 1 3

1 3 3 3 2 a 2 2 2 2 4

' , 1 1

8 2-

~ - . - , 0 1

1 4

, , 2

- , 8 Y 1

D

!. 4 U

- . 1 0

T S

. [ . ~

1 7-0

. \ .

. 3-1 0

8 r u e o r

3 t f

- . 2- a 9 w g a n t

w-_ .

8 1

9 9-9 3

Y D

U f

s o

e d

i r

u T m

. 2- S y e s t t i s

\ .

e t

ny C i s a l e at

" . t- )

7 ss e 8 e 9 dt 8 1 n an

. 3 (

E i 1

T e s A r) 5 D un t o

- , . 2- ai 7 2 r t 8

1 Y e a

. - pi 7 D m v t U e e T

. t- S t d 7

yd 4

- l r

. 7 ka 7 ed

. 2- en

.~ '

0 wa t

- 0

. - 2 esn g

6 ah 3

1 rt 8

ei vwh 8

A( c

. 8 0 .

. 3- 6 5 -

3 1

. 2-5 4 8

1 e 5

r 1 u

, 9- # g

. 5 Y i D F 2

5 U

T S

'k .

5 2

4 8

1 l

4 0 8 4 2 o 8 6 2 1 1 1 t

> &$u t $N cs

Site comparisons To gain further reassurance that the test water taken at high tide in Hampton Harbor was similar in character to offshore (intake) water, bivalve larvae data were examined (Figure 4.1-7). When Hvtilus edulis larvae were most abundant in 1987 (June-August) densities were quite similar at the two stations; any differences could be considered in the realm of normal natural spatial variability (NA1 1987).

These results indicate that the water taken at high tide should be fairly comparable.

l l

48

l Mytilus cdulis lirval d:nsiti:s ,

. i 140 - -1 J

120 -

l 100 -

h e .e- H-1 80 - +- P 2 1

uJ -l O 60 -

c b -

m 40 - A 20 -

l 0 0 , , , . , ,

\_

68 6 15 6-22 6 29 76 7-14 7 20 7 27 84 6 11 4

-l DATE (1987) 4 l

l Figure 4.1-7. Densities of mussel (Mytilus edulis) larvae offshore

! (P-2) and in Hampton Harbor (h-1) from mid-June to l

mi d- August , 1987. Seabrook Chlorine Minimization Study, 1987.

49 I

_ .a

\

I 1

5.0 LITERATURE CITED Normandeau Associates Inc. 1987. Seabrook Environmental Studies 1986. A characterization of baseline conditions in the Hampton-Seabrook area, 1975-1986. A preoperational study for Seabrook Station. Technical Report XVIII-II.

VAS Institute, Inc. 1985a. SAS User's Guide: Statistics, .

Version 5 Edition. SAS Institute, Inc., Cary, N.C. i 956 pp.

1 i

J l l

l 1

l l

i i

f 50

0.59 0.15 1 020CT87 1.00* 0.720 0.360 12.6 13.10 750 740 1.05 0.31 0.67 0.36 2 050cT87 0.00 0.000 0.000 . . . . 0.00 0.00- 0.00 0.00 2 050cT87 0.25 0.110 0.015 6.3 6.30 375 380 0.25 0.14 0.24 0.02 2 050cT87 0.50 0.260 0.051 12.5 12.70 .375 380 0.51 0.25. 0.46 0.05 l 2 050cT87 0.75 0.540 0.140 9.5 9.55 750 751 0.75 0.21 0.61 0.14 0.26 l

2 050cT87 1.00 0.740 0.260 12.6 12.75 750 751 1.01 0.27 0.75 2 070cT87 0.00 0.000 0.000 . . . . 0.00 0.00 0.00 0.00 3 070cT87 0.25 0.130 0.016 6.3 6.30 375 377 0.25 0.12 0.24 0.02 )

2 070cT87 0.50 0.250 0.060 12.5 12.70 375 377 0.51 0.26 0.45 0.06 l 2 070cT87 0.75 0.510 0.230 9.5 9.55 750 788 0.79 0.28 0.56 0.23 .l 2 070cT87 1.00 0.710 0.420 12.6 12.75 750 788 - 1.06 0.35 0.64 0.42 l 0.00 0.00 ?I 2 090cT87 0.00 0.000 0.000 . . . .. 0.00 0.00 2 090cT87 0.25 0.130 0.012 6.3 6.30 375 373 0.25 0.12 0.24 0.01 3 090cT87 0.50 0.250 0.051 12.5 12.10 375 373 0.48 0.23 0.43 0.05 2 090cT87 0.75 0.510 0.170 9.5 9.50 750 712 0.71 0.20 0.54 0.17 2 090cT87 1.00 0.690 0.370 12.6 12.80 750 712 0.96 0.27 0.59 0.37 4'

0.00 3 120cT87 0.00 0.000 0.000 . . . . O.00 0.00 0.00 3 120cT87 0.25 0.110 0.020 6.3 6.30 375 373 0.25 0.14 0.23 0.02 3 120cT87 0.50 0.310 0.061 12.5 12,10 375 373 0.48 0.17 0.42 0.06 3 120cT87 0.75 0.530 0.230 9.5 9.50 750 712 0.71 0.18 0.48 0.23 3 120cT87 1.00 0.690 0.390 12.6 12.80 750 712 0.96 0.27 0.57 0.39 3 140cT87 0.00 0.000 0.000 . . . . 0.00 0.00 0.00 0.00 3 140cT87 0.25 0.130 0.013 6.3 6.30 375 373 0.25 0.12 0.24 0.01 3 140cT87 0.50 0.260 0.057 12.5 12.10 375 373 0.48 0.22 0.42 0.06 3 140CT87 0.75 0.470 0.170 9.5 9.50 750 712 0.71 0.24 0.54 0.17 3 140cT87 1.00 0.700 0.230 12.6 12.80 750 712 0.96 0.26 0.73 0.23 3 160cT87 -0.00 0.000 0.000 . . . . -0.00 0.00 0.00 0.00 1 3 uccT87 0.25 0.130 0.020 6.3 6.20 375 390 0.26 0.13 0.24 0.02 3 160cT87 0.50 0.280 0.087 12.5 12.45 375 390 0.52 0.24. 0.43 0.09 3 160cT87 0.75 0.550 0.260 9.5 9.50 750 780 0.78 0.23 0.52 0.26 4

)

TA8LE 6.5-1 L!$7!NO 0F ALL RAW AND CALCULATED CONCENTRATION DATA.

DEMAND STUDY #4. SEPTEMBER 28 - NOVEMBER 11.

SEABROCK CHLORINE M!N!M1ZATION STUOY, 1987.

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13)

TARGET INITIAL FINAL CL INPUT RATE (ML/ MIN) CL STOCX CONC ACTUAL CHLORINE DEMNO FINAL WEEX DATE CONCENTRATION TR0 TR0 TARGET ACTUAL TARGET ACTUAL INPtfT CONC IN!Y!AL FINAL TR0 3 160cT87 1.00 0.720 0.390 12.6 12.80 750 780 1.06 0.34 0.67 0.39 4 190cT87 0.00 0.000 0.000 . . . . 0.00 0.00 0.00 0.00 4 190cT87 0.25 0.100 0.014 6.3 6.20 375 390 0.26 0.16 0.24 0.01 6 193cT87 0.50 0.210 0.051 12.5 12.45 375 390 0.52 0.31 0.47 0.05 4 190CT87 0.75 0.490 0.220 9.5 9.50 750 780 0.78 0.29 0.56 0.22 4 190cT87 1.00 0.680 0.340 12.6 12.80 750 780 1.06 0.38 0.72 0.34 4 210cT87 0.00 0.000 0.000 . . . . 0.00 0.00 0.00 0.00 4 210cT87 0.25 0.080 0.036 6.3 6.20 375 438 0.29 0.21 0.25 0.04 4 210CT87 0.50 0.440 0.150 12.5 12.45 375 438 0.58 0.14 0.43 0.15 4 210cT87 0.75 0.550 0.410 9.5 9.50 750 751 0.75 0.20 0.34 0.41 4 210CT87 1.00 1.100 0.770 12.6 12.80 750 751 1.02 0.00 0.25 0.77 5 260cT87 0.00 0.000 0.000 . . . . 0.00 0.00 0.00 0.00 5 260cT87 0.25 0.150 0.022 6.3 6.30 375 434 0.29 0.14 0.27 0.02 5 260cT87 0.50 0.380 0.140 12.5 12.60 375 434 0.58 0.20 0.44 0.14 5 260cT87 0.75 0.680 0.390 9.5 9.55 750 745 0.75 0.07 0.36 0.39 5 260cT87 1.00 0.770 0.560 12.6 12.20 750 745 0.96 0.19 0.40 0.56 5 280cT87 0.00 0.000 0.000 . . . . 0.00 0.00 0.00 0.00 5 280cT87 0.25 0.121 0.035 6.3 6.30 375 434 0.29 0.17 0.25 0.04 5 280cT87 0.50 0.332 0.109 12.5 12.60 375 434 0.58 0.25 0.47 0.11 5 280cT87 0.75 0.578 0.309 9.5 9.55 750 745 0.75 0.17 0.44 0.31 5 280cT87 1.00 0.776 0.513 12.6 12.20 750 745 0.96 0.19 0.45 0.51 5 300cT87 0.00 0.000 0.000 . . . . 0.00 0.00 0.00 0.00 5 300cT87 0.25 0.130 0.017 6.3 6.45 375 380 0.26 0.13 0.24 0.02 5 300cT87 0.50 0.210 0.051 12.5 12.20 375 380 0.49 0.28 0.44 0.05 5 300CT87 0.75 0.530 0.190 9.5 9.55 750 784 0.79 0.26 0.60 0.19 5 300cT87 1.00 0.660 0.360 12.6 12.60 750 784 1.05 0.39 0.69 0.36 6 02NOV87 0.00 0.000 0.000 . . . . 0.00 0.00 0.00 0.00 6 02Nov87 0.25 0.098 0.025 6.3 6.45 375 380 0.26 0.16 0.23 0.02 6 02Nov87 0.50 0.310 0.110 12.5 12.20 375 380 0.49 0.18 0.38 0.11 0 02N0v87 0.75 0.530 0.310 9.5 9.55 750 784 0.79 0.26 0.48 0.31 6 02Nov87 1.00 0.720 0.430 12.6 12.60 750 784 1.05 0.33 0.62 0.43 6 04Nov87 0.00 0.000 0.000 . . . . 0.00 0.00 0.00 0.00 0 04Nov87 0.25 0.140 0.024 6.3 6.30 375 380 0.25 0.11 0.23 0.02 6 04Nov87 0.50 0.310 0.130 12.5 12.50 375 380 0.51 0.20 0.38 0.13 6 04NOV87 0.75 0.530 0.310 9.5 9.50 750 784 0.78 0.25 0.47 0.31 6 04NOV87 1.00 0.680 0.450 12.6 12.50 750 784 1.04 0.36 0.59 0.45 6 06Nov87 0.00 0.000 0.000 . . . . 0.00 0.00 0.00 0.00 6 06Hov87 0.25 0.110 0.020 6.3 6.30 375 380 0.25 0.14 0.23 0.02 0 06Nov87 0.50 0.300 0.093 12.5 12.50 375 380 0.51 0.21 0.41 0.09 G 06Nov87 0.75 0.510 0.220 9.5 9.50 750 784 0.78 0.27 0.56 0.22 4 06Nov87 1.00 0.610 0.380 12.6 12. 5') 750 784 1.04 0.43 0.66 0.38 6 09N0v87 0.00 0.000 0.000 . . . . 0.00 0.00 0.00 0.00 6 09Nov67 0.25 0.160 0.044 6.3 6.30 375 408 0.27 0.11 0.23 0.04 6 09Nov87 0.50 0.420 0.210 12.5 12.50 375 408 0.54 0.12 0.33 0.21

i' TAGLE 6.5-1 LISTING OF ALL RAW AND CALCULATED CONCENT8,ATION DATA.

DEMAND STUOY #4. SEPTEMBER 28 - NOVEMBER 11.

SEA 8R00K CNLORINE NININ!ZATION STUDY,1987.

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13)

. TARGET INITIAL FINAL CL INPUT RATE (NL/M!N) CL STOCK CONC ACTUAL CNLORINE DEMNO FINAL WEEX OATE CONCENTRATION TRO TRO TARGET ACTUAL TARGET ACTUAL INPUT CONC IN!TIAL FINAL TRO 6 09Nov87 0.75 0.710 0.590 9.5 9.50 750 769 0.77 0.06 0.18 0.59 6 09Nov87 1.00 1.000 0.890 12.6 12.50 750 769 1.02 0.02 0.13 0.89 4

8 9

- - _ . _ _ . . . . . . . , , , . .

ML20246B834

Text

1.0 INTRODUCTION

1.0 INTRODUCTION

Navigation menu

Search