conjunctive use plan

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North Penn Water AuthorityConjunctive Use Plan

Updated 5/18/01


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North Penn Water Authority

Table of Contents

Conjunctive Use Plan

I. Introduction ........................................................................................................................ 3

II. Water Use and Resources............................................................................................... 4

A. Customer Analysis............................................................................................................ 41. Service Area ................................................................................................................... 42. Customer Growth Trend.................................................................................................4

B. Water Demand Analysis ...................................................................................................6

C. Water Source Analysis...................................................................................................... 7

1. Surface Water Source .................................................................................................... 7a. Description of Source ................................................................................................ 7b. Surface Water Capacity............................................................................................. 9

2. Ground Water Source .................................................................................................. 10a. Description of Source and Capacity ..................................................................... 10b. Ground Water Protected Area .............................................................................. 11

III. Conjunctive Use Management of Water Resources.....................................................13

IV. Conclusions and Recommendations.................................................................................. 16

List of Figures

1. Number of Customers, historical and projected (1970-2020)2. Customers by Classification (1999)3. Projected Water Demands4. Analysis of Average Annual Daily Demand5. Analysis of Maximum Day Demands6. Delaware River Basin7. Ground Water Protected Area

List of Tables

1. 1999 Year-end Customer Count2. 1999 Water Use by Class3. NPWA Wells Main System

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I. Introduction

What is a Conjunctive Use Plan?

There is a need to define conjunctive use in water resource planning because it can mean

different things depending on the situation. In certain areas of the country such as thesouthwest and southern California, water resources are scarce and the demand for water oftenexceeds the available supply. A Conjunctive Use Plan for these regions might include suchprograms as: water reclamation, inter-basin transfer of surface water, recharge of groundwater aquifers, and detailed water use accounting measures. In the northeast section of thecountry where North Penn Water Authority (NPWA) is located, we are fortunate to have ahumid climate, abundant precipitation and a comparatively modest growth rate so that waterresources, if used properly, are more than sufficient to meet the demands.

For North Penn Water Authority then, a Conjunctive Use Plan can be defined as follows:

The efficient use of available ground and surface water resources to provide a safe, reliableand abundant public water supply in a cost-effective manner"

The Authority first recognized the need for conjunctive use in the early 1970s when itbecame apparent that the steady and rapid growth of the region could not sustain the increasedwater needs by ground water alone. In hot summer months, there was the need to imposewater restrictions to ensure that basic water supply and fire protection were not compromised.To overcome this dilemma, a Conjunctive Use Plan was developed that resulted in thedevelopment of a surface water source, and in 1990, the Forest Park Water Treatment Plantbegan supplying surface water in addition to the existing ground water sources to meet theneeds of the region.

This updated plan includes a discussion of customer growth trends and increased waterdemands, existing water resources, and concludes with a discussion of the Conjunctive UsePlan strategy to meet the water needs of the area well into the future.

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II. Water Use and Resources

A. Customer Analysis

1. Service Area

The North Penn Water Authority (the Authority) was incorporated on August 10, 1964,under the Pennsylvania Municipality Authorities Act of 1945, as amended and supplemented,pursuant to actions taken by the Boroughs of Lansdale and Souderton and the Townships ofFranconia, Hatfield, Lower Salford, Towamencin, and Worcester. Since the originalincorporation, Skippack and New Britain Townships and Hatfield Borough have been addedas incorporating municipalities. The Authority provides water service to these municipalitiesas well as portions of the Townships of East Rockhill, Hilltown, Montgomery, and UpperGwynedd and New Britain Boroughs. All of these communities are situated in Montgomeryand Bucks Counties in Southeastern Pennsylvania.

2. Customer Growth TrendCustomer and population records and their relationship to past water demands serve as thebasis from which to project future water demands. A tabulation of the number of customersby class for each year is presented in Figure 1 and Table 1.

Figure 1

NUMBER OF CUSTOMERSNorth Penn Water Authority

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020

As of December 31, 1999, there were 25,436 customers (number of connections) in thesystem. These consist of 23,950 domestic customers, 1,079 commercial customers, 282industrial customers, and 125 public customers. A breakdown of these customers by classand municipality for 1999 is provided in Table 2. All customer connections are metered.Over the past 10 years, the Authority has been averaging approximately 700 new customersper year. From its inception, the Authority has averaged approximately 572 new customersper year. Ninety-four percent of existing customers are domestic and this percentage has beenfairly constant over the past 20 years. The Authority projects that it will serve at least 36,920

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customers by the year 2020, assuming the current growth pattern continues. Approximately34,760 of these will be domestic customers.

Municipality Domestic Commercial Industrial Public Total

East Rockhill Township 192 0 0 0 192

Franconia Township 2,467 47 30 4 2,548

Hatfield Borough 753 61 15 1 830

Hatfield Township 3,601 219 106 9 3,935

Hilltown Township 108 65 5 1 179

Lansdale Borough 4,868 279 59 32 5,238

Lower Salford Township 2,589 56 21 17 2,683

Montgomery Township 64 2 0 1 67

New Britain Borough 202 49 0 2 253

New Britain Township 602 10 2 3 617

Skippack Township 1,280 12 3 5 1,300

Souderton Borough 2,016 132 7 15 2,170

Towamencin Township 4,176 106 32 29 4,343

Upper Gwynedd Township 219 19 0 2 240

Worcester Township 813 22 2 4 841

Total 23,950 1,079 282 125 25,436

TABLE 1

NORTH PENN WATER AUTHO RITY

NUMBER OF ACTIVE CUSTOMERS BY MUNICIPALITY

1999 YEAR END CUSTOMER COUNT

Figure 2

Customers by Classification (1999)

94.2%

4.2%

1.1%0.5% Domestic

Commercial

Industrial

Public

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B. Water Demand Analysis

In 1999 the Authority sold on average, 7.39 million gallons per day (MGD) of water to itsmetered customers. The average daily demand (ADD), or water supplied to the system was8.94 MGD. Water use by class in 1999 is shown in more detail in Table 2. Unaccounted forwater, which is the difference between total water produced and purchased by the Authority

and total water sold, equaled 1.55 MGD or approximately 17.35 percent of the average dailydemand. Based on an estimated population served of 94,880, the average demand equaled93.9 gallons per capita per day (gpcd) in 1999.

Class

No. Of

Meters

Residential

Units

Total Gallons

Sold Dail Avera e

Percent of

Total

Domestic 23,950 32,605 1,896,766,396 5,196,620 58.15%

Commercial 1,079 1,470 313,324,610 858,424 9.61%

Industrial 282 305 426,108,881 1,167,422 13.06%

Public 125 139 58,972,530 161,569 1.81%

Other Utilities 616,074 1,688 0.02%

Unaccounted for Water 566,084,509 1,550,916 17.35%

Total 25,436 34,519 3,261,873,000 8,936,638

TABLE 2

NORTH PENN WATER AUTHORITY

1999 WATER USE BY CLASS

The ADD on the Authority water system is projected to be 11 MGD by the year 2010.Maximum day demand (MDD) is based on the maximum demand for any 24 hour periodduring the calendar year. For projection purposes, the MDD is approximately 1.4 times ADD,based on past trends. MDD is projected to increase from a current level of about 13 MGD to15 MGD by the year 2010. North Penn Water Authoritys historic and projected waterdemands are shown in Figure 3 following:

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Figure 3Projected Water Demands

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2

4

6

8

10

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16

18

20

1960 1970 1980 1990 2000 2010 2020 2030

Average Daily Demand Maximum Day Demand

Forest Park Capacity Total System Capacity

The projections indicate that by 2005, the MDD demand will exceed the surface water source

capacity and that ground water will be needed to meet demands. If higher levels ofconfidence are used in the statistical analysis, it is possible that MDD may exceed thiscapacity sooner given the variable nature of MDD. Also, growth trends indicate thatexpansion of total source capacity should be undertaken within the next 10 years, to ensurethat capacity needs are met beyond 2020. Without a ground water source, this significantcapital investment would be accelerated and design of the expansion would be underway now.

C. Water Source Analysis

1. Surface Water Source

a. Description of Source

The primary source of water supply for the Authority today is surface water from the ForestPark Water treatment plant located in Chalfont Borough. This represents about 73 percent ofthe total water demand. The remaining 27 percent comes from ground water sources. TheForest Part Water Treatment Plant (FPW) went on line in 1990, and since that time groundwater wells that were of marginal quality and/or capacity were phased out. Following areFigures 4 and 5, which show the relationship of surface water and ground water use. Thesegraphs illustrate that there has been a dramatic reduction in the use of ground water sinceFPW, however, ground water use has leveled off and is projected to rise modestly in the next

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20 years. Ground water will continue to be an integral part of the total source capacity wellinto the future.

Figure 4

Analysis of Average Annual Daily Demand

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2

4

6

8

10

12

Forest Park Water Ground Water Projected SW Use Projected GW Use

Figure 5

Analysis of MDD Demands

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2

4

6

8

10

12

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Proj. Groundwater Use Proj. Surface Water Use Hist. Groundwater use Hist. Surface Water Use

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A portion of the water in NBNC is diverted from the Delaware River, usually for about sixmonths of the year. The Point Pleasant Pumping Station pumps water from the DelawareRiver to the Bradshaw Reservoir, a small reservoir owned by PECO Energy Company, fromwhich the Authorities have acquired the necessary rights to use the reservoir. The water isdiverted into NBNC and onto Lake Galena at Peace Valley Park in Bucks County. ForestPark water operators control the flow of water from the lake continuing through NBNC to the

treatment facility. The Forest Park Water Treatment Plant draws what is needed to serve theNorth Penn and North Wales Water Authority customers.

The surface water source originates from the North Branch of the Neshaminy Creek (NBNC),which is part of the Delaware River watershed. The Delaware River watershed encompassesa large area beginning in upstate New York (see Figure 4). The mainstem Delaware Riverextends 330 miles from the confluence of its East and West branches at Hancock, N.Y. to themouth of the Delaware Bay. The river is fed by 216 tributaries, the largest being theSchuylkill and Lehigh Rivers in Pennsylvania. In all, the basin contains 13,539 square miles,draining parts of Pennsylvania (6,422 square miles or 50.3 percent of the basin's total landarea); New Jersey (2,969 square miles, or 23.3%); New York (2,362 square miles, 18.5%);

and Delaware (1,002 square miles, 7.9%). Almost ten percent of the nation's population relieson the waters of the Delaware River Basin for drinking and industrial use, yet the basin drainsonly four-tenths of one percent of the total continental U.S. land area (source of info: DRBC)

Figure 6Delaware River Basin

Flow into the Pennsylvaniasection of the Delaware River ispart of the lower basin with acapacity of over 40 billiongallons of water in this area of

the watershed. With propermanagement of this resource,there will be enough capacity tomeet the growth needs of thearea for years to come.

Approx. Locationof

Forest Park WTP

b. Surface WaterCapacity

The Point Pleasant PumpingStation has a capacity of 95

MGD of which 49 MGD is forpublic water supply and 46MGD is for cooling water forPECO Energys Limerick,Pennsylvania ElectricGeneration Station. Water forthe PECO power station isdiverted to the East Branch ofthe Perkiomen Creek and

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eventually to the Schuylkill River where it is drawn off to the generating station.

The two Authorities share equally in the plants water yield and capital and operating costs.On February 15, 1995, the Authority purchased the Point Pleasant Pumping Station and theCombined Transmission Main. This was an important step in securing a permanent anddependable source of supply.

The Forest Park plant had an initial nominal capacity of 20 MGD when it was first built and aPADEP-approved capacity rating of 16.7 MGD. The Authority holds contractual rights toone-half of the nominal capacity. With modifications to the loading rates on the filtrationunits, the DEP has approved a re-rating of the plant to a nominal capacity of 30 MGD.

With the combination of the Forest Park Water Treatment Plant and the Point PleasantPumping Station and related facilities, the North Penn Water Authority will have the ability toprovide substantial surface water to meet water demands in the rapidly developing CentralMontgomery and Western Bucks County area of southeastern Pennsylvania for theforeseeable future.

As projections indicate, though, additional capacity will be needed in the future and groundwater continues to play an integral part in meeting present and future needs solely from acapacity standpoint.

2. Ground Water Source

a. Description of Source and Capacity

Prior to 1990, the Authority was a 100 percent groundwater system consisting of over 70wells. As of this writing, the Authority operates 35 wells, which represents about 27 percentof the total water demand. The existing wells are divided between the main system and a

satellite system in East Rockhill.

All ground water sources are derived from bedrock aquifers within the Triassic LowlandSection of the Piedmont Physiographic Province and, within the NPWA service area, isprimarily underlain by the Brunswick Formation of Triassic Age. The Brunswick Formationconsists of reddish-brown shales interbedded with sandstone and siltstone. Just to the southof Lansdale and in portions of Worcester Township, the Lockatong Formation outcrops. Thisformation typically consists of gray argillite interbedded with beds of gray to black shale,siltstone, and marlstone.

The Brunswick Formation is the primary source of ground water in this area. Ground water

flow within the formation is mainly within secondary openings in the bedrock fractures alongbedding planes and joints. The fractures, along with overlying weathered rock and soil,provide the porosity necessary for ground water storage.

Aquifer properties are highly variable and can vary significantly even within a localizedregion. The yield and water bearing characteristics of a well that penetrates the Brunswickformation is highly dependent upon the width, number and network of water-bearing fracturesintersected by the well. Typical well yields in the Brunswick formation reportedly range from25-200 gpm, with the average well yield being less than 100 gpm. Following is Table 3, that

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lists the wells within the NPWA main system. There are two other wells in the E. Rockhillsystem not included in this table.

NPWA wells were constructed during the past 30 years. The pumping capacities of the wellsrange from a minimum of 30 gallons per minutes (gpm) to a maximum of 400 gpm. Safeyields range within the limits generally accepted for wells in the Brunswick formation. All

wells are pumped directly into the system by deep well pumping facilities and includeappropriate structures and equipment for efficient operation.

As part of the original Conjunctive Use Plan, those wells that were of marginal quantityand/or quality were removed from the system. Over 40 wells were abandoned or relegated toobservation well status. The remaining 35 wells that are currently on the system are generallylong-term producers with good or excellent water quality.

Treatment of each well supply consists of chlorination. In addition, four wells have beenequipped with packed towers for removal of volatile organic chemicals (VOCs) through airstripping. One well contains granular activated carbon (GAC) treatment, which will be

converted to an air stripper by the end of 2001. The existing well supplies are able to providea nominal yield of 7.3 MGD for short durations during normal periods. The drought yield ofthe Authoritys well supplies is approximately 4.7 MGD.

b. Ground Water Protected Area

The entire service area lies within the DelawareRiver Basin Commissions (DRBC) SoutheasternPennsylvania protected ground water zone (SeeFigure 5 across). As such, the DRBC has draftedspecific regulations regarding the permitting and

withdrawal of ground water within the area. Thegoal is to prevent depletion of ground water andprotect the interests and rights of lawful users of thesame water source, as well as balance and reconcilealternative and conflicting uses of limited waterresources in the region.

Lowered water tables in the Protected Area havereduced flows in some streams and dried up others.This reduction in base flows affects downstreamwater uses, negatively impacts aquatic life, and can

reduce the capacity of waterways in the region toassimilate pollutants. The goal of management of the protected area does not mean abolishingground water use but rather using ground water wisely and where appropriate adopting aConjunctive Use Plan such as this one that utilizes surface water in conjunction with groundwater.

Figure 7

The existing wells that remain in the NPWA system are for the most part not seasonaldependent and not detrimental to base stream flows. Those wells that were seasonaldependent have been abandoned, as part of the Conjunctive Use Plan.

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Future permitting of new ground water sources within the protected area need to satisfyDRBC regulations and demonstrate that there are no adverse impacts either on base streamflows or other ground water users in the vicinity. The potential for development of newground water sources for NPWA is still an alternative in less developed areas where theregulations can be met and the decision is cost-effective.

Table 3

NPWA Active Production Wells Main System (as of 2001)SAFE YIELD

Dur Dry Yrs Facilities

Well Depth Diam Limit Capacity

No. [ft] [in] (gpm) Output type [GPD] USE LOCATION

LANSDALE

L-10 264 8 47 T pump 100,800 Perm Mitchell Ave near Whites Rd

L-14 325 10 44 pump 144,000 Perm Norway Dr at Lakeview

L-17 387 10 46 pump 144,000 Perm Maple W of Hancock

L-18 406 10 84 pump 288,000 Perm Laurel Ln and Wissahickon Ave.

L-19 430 10 30 pump 72,000 Perm Norway Dr at Monticello Place

L-22 645 8 36 T pump 165,600 Perm E side Willow St

L-23 600 10 45 T pump 86,400 Perm Columbia Ave W of Cherry

SOUDERTON

S-10 300 8 32 pump 72,000 Perm W Chestnut St , Souderton

HATFIELD

H-4 494 10 56 * pump 100,800 Perm Roosevelt Ave E of Maple

H-6 495 10 52 * pump 150,000 Temp NIS Chestnut St @ Boro SP

H-8 500 10 83 * pump 150,000 Perm Fairgrounds Rd off Cowpath

H-10 305 8 150 * permit 300,000 Perm Orvil la Rd off Cowpath

H-12 503 104 permit 225,000 Perm Broad St Hanson's Textile Mill

NEW BRITAIN

NB-31 300 8 160 pump 345,600 Perm Tamamend Ave N of Pawnee N B Boro

NB-32 230 8 93 pump 146,880 Perm Seneca Dr N Britain Twp

NORTH PENN

NP-4 668 10 80 pump 144,000 Perm Allentown Rd N of Forty Foot, Towa.NP-5 630 10 205 T pump 360,000 Perm Fretz Rd E of Wambold, Towa.

NP-12 620 8 104 pump 172,800 Temp NIS Colmar, E Walnut St Hatfield

NP-14 585 10 208 * well 432,000 Perm Indian Creek Rd L Salford

NP-17 565 11 208 * well 576,000 Perm Kriebel Rd Towamencin

NP-20 300 8 81 * well 288,000 Emerg Laurel Ln L Salford

NP-21 500 12 213 T well 432,000 Perm Colmar, Crystal Rd Hatfield

NP-26 475 8 143 pump 216,000 Perm Morwood and Camp Rd Franconia

NP-29 410 8 50 * well 216,000 Emerg Rt 309 @ Maron Rd Hill town

NP-30 400 8 50 * well 216,000 Emerg PE R/W off Maron Rd Hil ltown

NP-31 500 10 77 * well 216,000 Perm Sumneytown Pk near Sturgis L Salford

NP-33 560 12 100 pump 216,000 Perm Rittenhouse Rd Towamencin

NP-34 335 10 124 # permit 211,000 Perm Schultz Rd Worcester

NP-39 510 8 112 * pump 360,000 Perm Township Line Rd off Church Skippack

NP-48 492 10 153 # permit 220,000 Perm Indian Creek Rd L Salford

NP-61 400 132 permit 288,000 Perm N P Hospital Broad St Hatfield

NP-68 463 69 permit 100,000 Perm Orvilla Rd Hatfield Twp

NP-69 500 8 100 permit 144,000 Perm Lawn Ave Souderton

Total Wells 4,710,240 gpd 7,298,880gpd

T requires treatment for VOC removal Temp NIS well rehab needed# limited by permit Emerg Emergency Use Only* if pump operated 24 hours Perm Well in service

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III. Conjunctive Use Management of Water Resources

The coordinated and integrated management of the Authority's surface and groundwaterresources, under a conjunctive use management program, optimizes the joint use of theavailable water resources in the most efficient, cost-effective manner. In general, increasedbenefits from the conjunctive management of all water supplies can be achieved over the

isolated management of either resource.

This section provides a brief comparative review of the characteristics of surface andgroundwater sources as it relates to NPWA. The different role of these two water sources in aconjunctively operated water system results directly from these characteristics. A discussionof the relative benefits of having two sources is included.

1. Availability and storageThe groundwater aquifer under the service area provides a natural long-term water storagereservoir for the service area. Unlike most surface water reservoirs, the ground water aquifercan typically store water for longer periods of time, making it more available when needed in

short-term drought years. The groundwater aquifer in Montgomery County is primarily theBrunswick Formation underlain by the Lockatong Formation (Longwill, Wood, 1965). Thisparticular aquifer is less likely to be have high storage coefficients due to the limited fracturesystem within the bedrock (Goode and Senior, 2000). The ideal way to determine the safeyield of wells within this aquifer is to pump them during drought situations to determine atrue safe yield. The remaining wells within the NPWA system have been through a numberof real-life drought scenarios and the safe yields reported in Table 2 are verifiable throughpumping records. This safe yield of close to 5 MGD is a significant and critical capacitysource during high demand periods.

The Delaware River basin is an excellent source of high-quality surface water that is managed

by the Delaware River Basin Commission (DRBC). The DRBC indicates that approximately40 billion gallons is the median storage level. The DRBC manages the supply during droughtsituations to ensure that water supply is not depleted. In 1996, the tidal estuary portion of theRiver of which FPW is located, used about 5 billion gallons, per day, which includes allprivate industry, electrical utilities and public water utilities. Utilizing water conservationmeasures, especially during drought seasons, has ensured an ample supply of water for allneeds.

Having two water supplies from different sources significantly enhances operationalflexibility and allows the system to function for short periods of time without the surfacewater plant. In cases where Forest Park is shut down, the well supply coupled with system

storage can meet normal demand needs for up to eight hours.

2. DistributionThe ground water aquifer is a natural distribution system, and thus reduces the need to buildlarge transmission lines within the distribution system. Wells can be installed throughout theservice area. Water stored in the groundwater aquifer can be made available when and whereneeded simply by controlling flow at the pump, as long as the aquifer has the water availableand the well is designed to have sufficient capacity.

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On the other hand, surface water requires that distribution systems be constructed andoperated to transport water from major withdrawal points to areas where it is needed in theservice area. With Forest Park Water being located at the easternmost portion of the system,it was necessary to construct large diameter transmission mains to convey water to thewestern portion of the system. Even so, the operational redundancy of having source ofsupply points throughout the system has enhanced the ability to meet peak demands and

maintain the pressure in the system during those high demand periods.

NPWA has made a successful transition to a multi-use conjunctive user by constructing largetransmission mains to the central portion of the service area for distribution, whilemaintaining a network of wells throughout the distribution system

3. Water quality and treatmentAs part of its conjunctive use plan, NPWA eliminated wells that were of poor quality orexpensive to operate. The remaining wells are now cost-effective producers with minimaltreatment.

The water supply for Forest Park Water is of excellent raw water quality and is utilizing state-of-the-art technology to produce the highest-quality water. The geographic location of thefacility, however, can make it more challenging to maintain a chlorine residual in the westernend of the system. Utilizing the existing ground water sources has proven to be an excellentrechlorination mechanism to ensure that a safe drinking water is always available to ourcustomers.

Water temperature for groundwater is very stable and typically varies between 50-55 degreesF. Surface water, on the other hand, can vary from 35-40 degrees during a cold spell in winterto 60-65 degrees during the height of summer. Research has shown a direct relationshipbetween water temperature, bacteriological activity and internal corrosion rates. As watertemperature rises, so does bacteriological activity and corrosion rates associated with theincreased activity. Above 60 degrees F, activity increases significantly (LeChevallier, 2001)The wells have had a mitigating effect on water temperature fluctuations and in this regard,have aided corrosion control efforts. Seasonal fluctuations of temperature in spring and fall,also can contribute to thermal expansion and contraction of pipe material and increasedincidence of main breaks. Wells, also help to mitigate this effect, especially if they arelocated near a transmission main.

4. CostsInitial investment in well/pump installations can be risky because long-term safe yields areestimated and sometimes the actual yield is less than expected reducing the overall cost-effectiveness of the installation. In addition, since the service area is located within a GroundWater Protected Area, the regulations require significant monitoring and observation of theproposed withdrawal to determine the impacts on the aquifer and other users. Also,hydrogeological studies will need to incorporate ground water flow models as part of theanalysis to develop the relative risk of future contamination of a new source. The cost todevelop a new ground water source under this scenario could range between $500,000 to$750,000 or more based on current costs. This is more expensive than previous NPWA wellinstallations, however, these precautionary planning measures were not an issue for olderinstallations and the region at that point, was not a ground water protected area, among other

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reasons. Though a new ground water source may be more expensive than in the past, it is stillgenerally much less expensive compared to building a surface water treatment plant, andinstalling the larger pipes required for distribution from a centralized point.

For NPWA, constructing FPW was needed because the availability of ground water supplywas outstripped by the escalating demands for water and therefore, the need to develop a

surface water supply was the best available option. The operating costs for the remainingwells in the NPWA system are comparable to the incremental operating costs to producewater from its Forest Park Plant. The costs to develop a new ground water source of supply,however, would add significantly to the overall life cycle costs of a new ground water facility.

5. Reliability and local controlFrom the perspective of reliability and local control, groundwater is superior to surface wateras a supply source for the Authority. Surface water is more susceptible to hydrologicfluctuations, institutional controls, decision-making power located outside the Authority, andcompetition from a wider array of water users throughout the tri-state area.

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IV. Conclusions and Recommendations

A summary of the conclusions reached in this report are as follows:

NPWA will continue to experience a high rate of growth between 2 and 5% per year

for the foreseeable future, primarily in suburban expansion of larger, more affluentpopulation centers. This will continue to cause a significant increase in demand forpotable water and a corresponding increase in the use of NPWA available watersource capacity.

Ground water use by the Authority will continue to play an integral role in total waterresource capacity in order to effectively meet the growing water demands. Thiscapacity will enable NPWA to delay significant capital investment in the expansion ofForest Park Water Treatment Plant.

Since 1991, approximately 40 wells have been removed from the system so that wellsof marginal quality or capacity have been eliminated. The remaining 39 wells are ofexcellent quality, have an established safe yield and are cost-effective producers

relative to the incremental cost of producing surface water from Forest Park. Forest Park surface water originates as part of the Delaware River Basin and as such is

subject to the rules and regulations of the Delaware River Basin Commission (DRBC).The DRBC monitors water usage and stream flows to ensure that ample capacity isavailable for all users.

The entire NPWA service area lies within the DRBC Ground Water Protected Area sothat future ground water withdrawals will be subject to the restrictions and limitationsof these regulations. Further, development of ground water supplies in less developedareas is possible if warranted, but will require significantly higher expenditures inorder to satisfy the regulations.

Having the capability to use both ground and surface water significantly enhances

operational flexibility to the benefit of the Authority. In the event that there is aproblem with the transmission main or the plant needs to shutdown for a short period,the combination of ground water and system storage can meet demands withoutservice disruption.

NPWA has made a successful transition into a conjunctive water user by constructinglarge diameter transmission mains from Forest Park to the central portion of thesystem so that surface water is readily available to all customers in a cost-effectivemanner. Ground water withdrawal points are spaced throughout the system tomaximize system reliability and efficiency.

Ground water plays an important role in mitigating some negative aspects of surfacewater from a water quality perspective. The higher temperatures of surface water in

warm weather months will accelerate internal corrosion rates in the distributionsystem. Also, sudden temperature changes of surface water in the fall and wintermonths affect thermal expansion of iron pipes resulting in increased main breaksduring this time. The stable temperature of ground water (50-55 degrees F, all yearround) helps to dampen these temperature fluctuations and improve systemperformance.

Use of wells within the system allow for chlorine residual injection points so that onlymodest levels of chlorine residual are needed from the plant. Otherwise, higher levelof chlorine residuals would be needed at the plant to the detriment of nearby

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Based on the findings and conclusions in this report the following recommendations are

made:

Continue to use ground water as a significant source of supply.

Monitor and research the effects of mixing ground water and surface water tomaximize the operational and water quality benefits of both sources.

Investigate the cost-effectiveness of additional ground water sources compared tothe surface water source. Factor in all operational benefits and costs, delaying ofother capital investments and all life cycle costs into the analysis.

In conjunction with North Wales Water Authority, set target dates to begin andcomplete the design and permitting of the expansion of the Forest Park WaterTreatment Plant.

In conjunction with North Wales Water Authority, set a moving target for the plantto go online and continue to monitor and reassess annually, system demands andneeds to determine the optimal time for this significant capital expenditure.

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References

Goode, Daniel J. and Senior, Lisa A., 2000, Simulation of aquifer tests and ground-waterflowpaths at the local scale in fractured shales and sandstones of the Brunswick Group andLockatong Formation, Lansdale, Montgomery County, Pennsylvania

LeChevallier, Mark W., 2001, Maintaining water quality in the distribution system:significance and control of biofilms, Presentation at AWWA Technology TransferConference, Chicago.

Longwill, S.M. and Wood, C.R., 1965, Ground-water resources of the Brunswick Formationin Montgomery and Berks Counties, Pennsylvania: Pennsylvania Geological Survey, 4thSeries, Ground Water Report W22

DRBC Website: http://www.state.nj.us/drbc/drbc.htm, various pages as of 5/16/01.
http://www.state.nj.us/drbc/drbc.htmhttp://www.state.nj.us/drbc/drbc.htm

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