ML20198N806

NPDES Permit PA-0052221 Study Plan for Fecal Coliform Bacteria in Pont Pleasant Water Diversion Sys During May- Sept 1998

ML20198N806
Person / Time
Site:	Limerick
Issue date:	12/31/1997
From:	NORMANDEAU ASSOCIATES, INC.
To:
Shared Package
ML20198N804	List: ML20198N799 ML20198N806
References
PROC-971231, NUDOCS 9801210221
Download: ML20198N806 (6)

Text

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STUDY PLAN FOR FECAL COLIFORAt HACTERIA IN Tile POINT PLEASANT WATER DIVERSION SYSTEh! DURING h!AY- SEPTEMBER 1998 NPDES Permit No. PA-0052221 PREPARED FOR:

PECO Energy Company 2301 Starket Street Philadelphia, Pennsylvania 19101 PREPARED BY:

Normandeau Associates,Inc.

3450 Schuylkill Road Spring City, Pennsylvania 19475 t

December 1997 l

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STUDY PLAN t FOR FECAL COLIFORAI HACTERIA IN THE POINT PLEASANT WATER DIVERSION SYSTEM DURING MAY- SEPTEMBER 1998 ,

INTRODUCTION PECO Energy Co.'s (PECO's) Limerick Generating Station (LGS) relies on the Delaware River as a source of consumptive cooling water annually from about May through November when the Schuylkill River is unavailable for consumptive use due to flow and temperature constraints imposed by the Delaware River Basin Commission. Delaware River water is conveyed to LGS via the Point Pleasant Water Diversiun System (Figure 1). Delaware River water is withdrawn at Point Pleasant, pumped to Bradshaw r Reservoir, and piped to a discharge outfall in the headwaters of the East Branch Perkiomen Creek (EBPC). Thereafter the water is conveyed via open channel flow to the ,

mainstem Perkiomen Creek and is then withdrawn at a pumpstation at Graterford for fmal conveyance vm ;,ipeline to LGS.

The discharge from Bradshaw Reservoir to the EBPC is governed under NPDES Permit PA 0052221. One requirement of the Permit limits monthly fecal coliform bacteria (FCB) concentrations to 5 day geometric means of 200 colonies /100 ml from 1 May through 30 -

September and to 2000 colonies /100 ml in all other months. Geometric means are calculated from samples collected on five separate days within a given month.

PECO has achieved an 85% rate of compliance with the FCB limitation in the May through September period. However, the available data suggest that there is significant uncertainty in FCB dynamics (spatial and temporal variation), such that the discharge of water disinfected with ozone has only minimally improved FCB levels in the EBPC. In-stream FCB concentrations in the diversion enhanced stream approach pre diversion levels within 6 km downstream from the outfall (Branch Rd.,40% ofindividual data points <200 C/100ml post diversion vs. 30% pre-diversion). The observed improvement at the Branch Rd. sampling station may have occurred even without disinfection, because FCB concentrations in Bradshaw Reservoir are lower (62% < 200 C/100ml) than levels observed upstream of the outfall in the EBPC (43% < 200 C/100ml) and levels observed at Branch Rd. in the pre-diversion period (30% < 200 C/100ml).

Based on the monitoring results obtained to date, PECO is requesting approval to suspend the FCB limits during May through September 1998 and perform an intensive study to evaluate spatial and temporal variation in FCB levels in the EBPC and water transfer system without disinfection. Through evaluation of representative data in 1998 and comparison with historic data, the study will evaluate both the past eflicacy of disinfection and the extent to which untreated diversion inflow provides lower FCB concentrations in the upper EBPC than would otherwise exist.

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o METflODS AND MATERIALS i I

3ackground Since the initiation of the Bradshaw discharge to the EBPC in 1989, five or more FCB samples have been collected at the outfall each month for the purpose of determining compliance with limits contained in the NPDES permit. With few exceptions additic,al samples weie colle:ted at about the same time at a location just upstream of the outfall in the EBPC and in Bradshaw Reservoir near the inlet to the pumphouse. In 1997, additional samples were obtained from the EBPC at the Bucks Rd. gage, located about 1.4 km downstream of the outfall. All sites were sampled on the same day with minimal technician travel time between samples.

FCB data are also available from a separate water quality sampling effort for the aquatic biological monitoring program. Samples were obtained biweekly from the Delaware River near the Point Pleasant Pumping Station and at three sites (Branch Rd., Cathill Rd., and Garges Rd.) downstream of the Bucks Rd. gage in the EBPC. Branch Rd., located about 4.5 km below the outfall, is the site in this program that is located closest to the outfa!l.

Data from this program are available for several years prior to diversion operation as well as the operational period.

Sample Design Seven sampling sites (Delaware River, Bradshaw Reservoir, Outfall, EBPC - upstream, Bucks Rd., Morris Run, and Branch Rd.; Figure 1) will be sampled for this special study.

Although the primary focus of sampling in 1998 is the EBPC, contemporaneous data from the Delaware River and Bradshaw Reservoir will allow better description of FCB dynamics throughout the water transfec system The three sampling sites in EBPC extend from just upstream of the outfall to Branch Rd. and provide spatial coverage to the stream reach most influenced by diversion flow. These locations were also selected to at least partially isolate other sources cf potential FCB contamination which may exist independently from the diversion.

For this same reason, a sampling station in Morris Run,just upstream ofits confluence with the EBPC, will provide data on the influence of this tributary on the mainstem EBPC.

Morris Run is the largest tributary to the upper EBPC and is a potential sot.rce of FCB. It enters the EBPC just upstream of Branch Rd. and during the pre-diversion period, it contributed about 50% of the flow observed at Branch Rd. Watershed and land-use characteristics are very similar to those that existed in the headwaters of the EBPC prior to the onset of diversion. Since Morris Run is unafrected by diversion, evaluation of

- Morris Run FCB trends during 1998 provides a mechanism for estimating what ambient conditions in the EBPC might be like today without the diversion.

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L Single FCB grab samples will be collected at each of the sampling stations in rapid sequence on a systematic basis, (e.g., every two - three days) to yield at least 10 samples per station per month (May- September). Systematic sampling may include some weekend days, and will be scheduled without regard to the status ofdiversion operation.

The chosen sampling interval is sufliciently small to avoid phase-lock with weather fronts or other cyclic phenomena which might drive instream FCB concentrations (e g., via runofl), and will ensure that monthly sample mean FCB concentrations are relative'y unbiased aad representative of the monthly mean, and that sample to-sample trends will provide the description of the spatial and temporal dynamics of FCB concentrations in the EBPC needed to evaluate water quality management alternatives.

Sampling Protocol Actual sampling locations at each of the sampling stations will be clearly marked to assure samples are always taken from the same location at a given station. A graphical and/or pictorial sampler's guide that depicts the sampling locations will be prepared and made available to the technician prior to onset of the sampling program to facilitate consistent sampling at the specif ed locations. The guide will also contain other information pertinent to this sampling program (e g., travel directions, laboratory location, parameters to determine in the field, time schedules, sample preservation, and key contacts / phone numbers). The stations will be sampled in the same order and at approximately the same time of day for each station, so as to minimize such extraneous sources of variation.

Sample containers will be sterilized wide-mouth plastic or glass containers of at least 50ml capacity. They will be obtained from the analyticallaboratory scheduled to perform the analyses. The containers will be labeled both on the cap (metal or plastic is acceptable) and on the body of container itself. Labels will include the sample lo ation, date, time, and collector's imtials. Immediately afler sampling, the sample centainer will be sealed with the label or other suitable material in such a way that it will be necessary to break the seal to open the container, Grab samples will be obtained from stream locations by approaching the location from downstream to avoid sampling sediment disturbed from the stream bottom Care will be taken by the technician to avoid touching and contaminating the inner surfaces of the containers. The container cap will be held carefully during sampling. Care will be taken to avoid sampling the surface film or bottom sediment. Water fromjust below the stream (or reservoir) surface will be introduced directly into the sample container without pre-rinsing. The container will be filled and the cap replaced promptly. Samples will be transponed on wet ice or ice packs in coolers of appropriate size and constiuction.

Samples will be delivered to the analytical laboratory within the required 6-hour holding time. A chain of custody form provided by the laboratory (or equivalent form) will be completed for each set of samples.

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Samples will be collected and handled only by personnel trained in proper collection  !

techniqbes. FCB concentrations will be determined according to Standard Method 9222D -

Membrane Filter Technique by a PADEP certified laboratory. l s

- Water temperature at the time of sample cellection at each location will be measured and recorded by the technician. Daily diversion pumping rates and stream flow at the Bucks Rd. USGS gage and precipitation data from the nearest monitoring station will also be-obtained. j Data Analysis 4

The sampic results will be used to generate estimates of mean FCB concentrations for l each month and investigate pattems of spatial and temporal variation. Variables ofinterest i include monthly mean FCB concentration at each station, variance, autocorrelation - )

structure, and correlations with measured covariables such as stream flow, water  ;

temperature, rainfall, etc. The resulting data will yield a better representation of FCB ,

dynamics in relation to such driving variables than any existing data. For example, the mean from all sample dates in the month should be close to the underlying mean FCB i concentration (which is a continuously variable phenomenon) and should be unbiased as l long as the sampling interval does not coincide with some periodic cycle in FCB variation.

Data will be evaluated using various statistical techniques such as analysis of variance, time series analysis, and correlation and regression of FCB concentrations against independent variable such as station location, rainfall, stream flow, etc.  !

A report of the findings of this study will be prepared and a copy will be provided to the PADEP within 90 days of the last sampling date.

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