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Joint Water CommissionWater System Feasibility Study

Prepared by:Environmental Financial Group, Inc.Brown and CaldwellPerlorica, Inc.

September, 2002

Water System Feasibility StudyPage i

TABLE OF CONTENTS

SECTION 1. EXECUTIVE SUMMARY Page 1

SECTION 2. INTRODUCTION Page 9

SECTION 3. WATER SUPPLY Page 15

SECTION 4. WATER DEMAND 3

SECTION 5. WATER TREATMENT Page 28

SECTION 6. DISTRIBUTION AND STORAGE Page 48

SECTION 7. ECONOMIC AND FINANCIAL FEASIBILITY Page 51

Water System Feasibility StudyPage 1

SECTION 1

EXECUTIVE SUMMARY

At the request of the Joint Water Commission (JWC), this WaterSystem Feasibility Study report has been prepared byEnvironmental Financial Group, Inc. in association with Brown &Caldwell and Perlorica, Inc. The Study, conducted over the pasteight months, was an evaluation of the feasibility of developing anew, independent water supply and treatment system to serveGolden Valley, Crystal and New Hope. It was prompted byincreases in the cost of purchasing treated water from the City ofMinneapolis (Minneapolis).

Since 1961, JWC member cities have relied on Minneapolis fortheir water supply. Minneapolis delivers treated Mississippi Riverwater to JWC reservoirs located in Golden Valley and Crystal.The JWC then pumps that water from those reservoirs to servecustomers. An agreement between Golden Valley andMinneapolis supporting these water purchases expired in 1991.Since then, the JWC has continued to purchase water fromMinneapolis under the terms and conditions of the expiredagreement. In March of 2002, a Memorandum of Understandingwas executed which continued the terms and conditions of theexpired contract through December, 2004.

In the mid-1990s, the JWC began examining alternatives to aMinneapolis water supply. In 1997, the JWC completed anAlternate Water Supply Study that pointed to the Prairie du Chien/ Jordan aquifer as a potential source of groundwater. The 1997Study concluded that continued increases in the cost ofMinneapolis water could make an alternate supply economicallyattractive.

In early 2002, under the terms of the Memorandum ofUnderstanding, Minneapolis began charging the JWC an interim


rate of $2.07 per thousand gallons. This was prompted byincreases in Minneapolis’ cost of providing service to the JWC asdemonstrated by a Cost of Service Proposal submitted to the JWCin 2001. JWC customers are currently paying $1.89 per thousandgallons and financing an additional $0.18 per thousand gallonson an interest-only basis. This rate, a 76.9 percent increase over2001 rates for Minneapolis water, coupled with planned futureprice increases totaling 44 percent from 2003 through 2007,prompted the JWC to authorize this Water System FeasibilityStudy.

Study Goals and Objectives

The overall goal of this Study was to determine the most cost-effective way to continue to provide high quality water to JWCcustomers. The objectives of the Study were threefold.

• Assess the technical and economic feasibility ofdeveloping an independent water supply and treatmentsystem.

• Develop a Practical Water System Concept that wouldprovide customers an equal or better water quality andutilize existing distribution and storage infrastructure.

• Evaluate the ability of membrane treatment technology tocost-effectively provide a finished water quality that meetsfederal and state regulations and that meets or exceedscustomer expectations.

Base Water System Concept

For evaluation purposes, a “Base Water System Concept” wasdeveloped to evaluate technical and financial feasibility in moredetail. Illustrated in FIGURE 1-1 below, this planning conceptincludes twin water treatment facilities able to produce 22 milliongallons of treated water per day (mgd). The two treatmentfacilities were assumed to be located near the Crystal and GoldenValley finished water reservoirs. The treatment facilities utilize amembrane softening treatment technology, providing both a


mechanical barrier against viruses and contaminants andrequiring a smaller building footprint. (Identifying specificlocations of the facilities was beyond the scope of the Study.)Each treatment facility was planned to be expandable to provide atotal of 24 mgd of treated water through the installation ofadditional membranes.

The treatment facilities were assumed to be served by a series ofraw water wells centrally located within the service area.Groundwater pumped from these wells would be transmitted tothe treatment facilities via a system of raw water transmissionmains. (Identifying the routes of these raw water pipelines andspecific locations of the wells was beyond the scope of thisStudy.)

Conclusions

The following conclusions may be drawn from the Study.

• It is technically feasible to develop a water supply andtreatment system that provides customers a water quality atthe tap equal to or better than that provided by the City ofMinneapolis. Groundwater could be pumped from wellsand treated in twin treatment facilities located near bothwater reservoirs. Existing storage and transmissionfacilities would be fully utilized under the plan concept.

• Such a system could be developed at an estimated $45million. Annual costs, including debt service payments onassumed bond financing, are estimated to be $2.28 perthousand gallons. The cost of Minneapolis water iscurrently $2.07 per thousand gallons (2002). Minneapolisbudget documents from 2001 report projected annual costincreases in each of the next several years.

• Membrane softening technology is more cost-effective thanconventional lime softening and other treatmenttechnologies. Membrane technology also requires smallerfacility footprints, reducing potential siting difficulties.Pilot testing would be required to select a specific


membrane product and confirm many other technicaldetails.

• Groundwater is available from a proven, reliable, andregulated aquifer source. Groundwater modeling andpermitting would confirm this conclusion prior toexpending funds on new wells and treatment facilities.

• The JWC could provide “first water” from such a system by2005 if it decided this fall to continue project developmentefforts. The next step would be to conduct groundwatermodeling and test various membrane products at anapproximate cost of $200,000.

• All major infrastructure projects have inherent risks.TABLE 1-2 presents a summary of some of these risks andpotentially mitigating factors. Pilot testing andgroundwater modeling prior to construction of well fieldsor treatment facilities would mitigate some of these risks.Membrane performance and replacement cycles may beguaranteed through an agreement with the membranemanufacturer. Such agreements are becoming common inthe water utility industry. Developing a new water system,however, remains a complicated and expensiveundertaking.

• Financing the program would require debt financingthrough either a single sponsoring city or pro rata sharesfrom each of the three JWC member cities. Ownership ofthe new facilities would also have to be decided upon.These arrangements would all have to be supported byappropriate changes to the intergovernmental agreementsdefining the JWC. Other institutional changes might bewarranted, but such an analysis was beyond the scope ofthe present Study.


FIGURE 1-1. Water System Concept


TABLE 1-1. JWC WATER SYSTEM COST SUMMARY

Cost ($000)

Water Treatment Plant No. 1 17,200,000$ Water Treatment Plant No. 2 17,200,000 Wellfields and Pipelines 10,600,000

TOTAL COST 45,000,000$

Annual Debt Service 3,459,000$ Annual Operations & Maintenance Cost 2,975,000 Administrative Overhead 75,000

TOTAL ANNUAL COST 6,509,000$

Indicated Cost per Thousand Gallons (2.85 Bgal) 2.28$

Current (2002) Cost of Minneapolis Water 2.07$

Construction Costs assume 2003-4 dollars, O&M costs assume 2005 start-up.Annual debt service assumes 20-year bonds at an average bond rate of 4.5 percent.Annual O&M includes renewals and replacements.Indicated cost based on 2.85 billion gallons annual water purchase (1998-2001 average).Current cost of Minneapolis water is $2.07 per thousand gallons---$1.89 per thousand gallons is reflected in current JWC ratesand an additional $0.18 per thousand gallons is being deferred under interest-only financing from Minneapolis.


TABLE 1-2. Risks and Possible Mitigating Factors

Risks Mitigating Factors

Inability to obtain a groundwater permit. DNR optimistic. Could be evaluated bygroundwater modeling and testing priorto construction.

Neighboring wells are affected bylowering water table.

Could be evaluated by groundwatermodeling and testing prior to committingadditional funds to the project.

Energy costs increase substantially. The system has substantial storage thatwould allow for off-peak treatmentunder certain conditions. Despite this,future energy costs increases remain arisk.

Well sites cannot be identified or acquired. Wells could be located on suitable city-owned sites. Soundproofing andarchitectural treatment of well housescould address citizen concerns.

Operator error causes expensive damageto membranes.

Such risks may be shifted to vendors—or,the membrane manufacturer could assistin start-up and training.

The membranes foul or do not meet waterquality criteria.

These risks could also be reduced bypilot testing membranes prior to full-scale installation. Much less likely withrecent membrane installations. Somerisks could be shifted to vendors.

Chemicals (chlorine, acids, and others)would be stored and used in areaspotentially located close to residences andbusinesses. Spills would be disastrous.

The Department of Health would requireadequate containment and scrubbersystems to be available in the event of aspill. Not unlike other municipalinstallations.

There is an unexpected increase in waterdemand due to higher density residentialor industrial development.

The Water System Concept includesreserve capacity for future growth.


Practical, Non-Cost Implications

Aside from the apparent economic and technical feasibility of anew water supply and treatment system, undertaking a largepublic works program has significant, non-cost implications thatwill have to be addressed in order to successfully develop theproject.

• Several new pipelines will have to be constructed. Muchof that work will occur in the public right-of-way. Streetswill have to be reconstructed, with associated trafficdelays.

• Wells and water treatment facilities will have to be sited inareas conducive to their achieving proper function as partof the water system. In some cases, private land may haveto be acquired to construct such facilities.

• Extra efforts may need to be taken to make these facilities“good neighbors” since they may be located in or adjacentto residential and commercial areas.

• The JWC and its member cities will have to determine themost appropriate way to operate the new facilities. Suchoperations will require water treatment expertise.

• The JWC and its member cities will have to determine themost appropriate way to manage development of a newwater system. Multiple design and construction contractswould be underway simultaneously, requiring a dedicatedteam of individuals to manage the effort.

• Ownership of the new facilities will require updatedintergovernmental agreements, possibly requiring re-organization of the JWC.

• Communications and public education efforts duringconstruction and start-up will require careful planning andexecution.


SECTION 2

INTRODUCTION

In January 2002, the Joint Water Commission (“JWC”) authorizedpreparation of this Water System Feasibility Study to evaluate thefeasibility of developing a new, independent water system toserve its member cities: Golden Valley, Crystal and New Hope.The Study was prompted by a cost of service proposal submittedto the JWC by the City of Minneapolis (“Minneapolis”) as part of anew, long-term water service agreement. The proposalsignificantly increased the cost of Minneapolis water to the JWC.

Background

On July 18, 1961 the Village of Golden Valley (Golden Valley)entered into a water purchase agreement with Minneapolis. Theagreement relied on an existing 1927 franchise authorizingMinneapolis to install and maintain a 48-inch water line withinthe corporate limits of Golden Valley. From 1961 to 1963,Minneapolis furnished water to Golden Valley “on demand”,providing a continuous supply twenty-four hours a day.

Under the terms of the agreement, Golden Valley invested in andretained title to the facilities necessary to meter, transmit, store,and distribute water from point or points of delivery ofMinneapolis water to Golden Valley customers. Golden Valleyreserved the right to supplement its water supply with any supplyapproved by the Department of Health, as long as suchsupplemental supplies did not enter Minneapolis’ water system.Golden Valley also agreed to impose on its customers waterusage restrictions that are imposed, citywide, by the City ofMinneapolis.

Beginning in 1964, Minneapolis provided water to Golden Valley(now re-selling water to Crystal and New Hope) on an “off-peak”


basis up to a maximum 1.5 million cubic feet per day. Off-peakdelivery was defined as a daily 12-hour period of leastconsumption, as selected by Minneapolis. During periods oflower system-wide demand, additional hours could be arrangedby mutual agreement. To accommodate this off-peak delivery,appropriate storage facilities were constructed. An off-peakdelivery arrangement continues to this day.

The cost of water sold by Minneapolis is a set percentage of therate charged by to Minneapolis customers residing inside the citylimits. The rate is dependent on the total amount of waterpurchased in each month, as presented in TABLE 2-1 below.TABLE 2-2 presents 1997 – 2002 costs to the JWC of Minneapoliswater.

TABLE 2-1. Minneapolis Rate Schedule

Monthly Consumption, Million Cubic Feet Percent of Inside-City Rate

First 0.4 125 %Next 2.1 80 %Next 4.5 44 %Next 6.0 40 %

All Over 13.0 32 %

TABLE 2-2. JWC Cost of Minneapolis Water, 1997 - 2002

YearAverage Price perThousand Gallons Percent Increase

1997 $ 0.891998 1.00 12.3 %1999 1.09 9.02000 1.17 7.32001 1.89 61.52002 2.07 9.5


The Golden Valley, Crystal, and New Hope Joint WaterCommission. On November 12, 1963 an intergovernmentalagreement was executed between Golden Valley, Crystal, andNew Hope to jointly construct, operate, and maintain a watersystem to distribute water purchased from Minneapolis to theresidents of the three cities. The agreement created the GoldenValley, Crystal, and New Hope Joint Water Commission (JWC).The JWC is comprised of the city managers of each city. Underthe agreement, Golden Valley purchased water through its 1961contract with Minneapolis and re-sold it to Crystal and NewHope.

The JWC currently operates, maintains, repairs, and replaces jointwater system facilities. Reservoirs and pipelines greater than 12inches in diameter are defined to be joint facilities. Operationsand maintenance expenses are allocated between the three citieson a pro rata basis based on water purchases. In 1969, anaddendum to the agreement was executed allowing extension ofservice to a small number of customers located in the City ofRobbinsdale. Other than that, the JWC serves only the residentsof the three member cities.

Alternate Water Supply Studies. The water purchase agreementbetween Golden Valley and Minneapolis expired in 1991. As inpast years, the JWC continues to purchase water fromMinneapolis at a rate indexed Minneapolis inside-city residentialrates. These rates have increased over the past several years dueto planned maintenance and improvements to the Minneapoliswater system. In particular, Minneapolis is embarking on anadvanced water treatment program at both its Fridley andColumbia Heights water treatment plants. This $140 millionprogram is planned to be completed in 2007. It is planned to befinanced from bonds supported by water user charges.Minneapolis has increased rates to its customers over the pastseveral years to prepare for this project and make otherimprovements to its water system. Minneapolis budgetprojections for this program are presented in TABLE 2-2.


TABLE 2-2. Minneapolis Water Works Budget Projections (millions $)

2001 2002 2003 2004 2005 2006 2007

Columbia Heights FiltrationPlant Advanced TreatmentImprovements

4 3 23 23 0 0 0

Fridley Filtration PlantAdvanced TreatmentImprovements

4 3 0 0 21 41 20

Bond Sales 9.5 7.5 22.1 23.3 26.4 55.1 33.6

Water Rate Increases 9.7% 9.9% 9.5% 8.7% 8.4% 5.8% 5.5%

Pay-As-You-Go (Cash-FundedCapital Improvements)

4.0 4.5 5.0 5.5 6.0 6.5 N/a

Debt Service Payments 10.5 11.9 12.5 13.6 12.9 16.8 N/a

Fund Balance 2.0 0.8 1.6 3.5 8.6 11.2 N/a

Source: City of Minneapolis, 2001 Budget Documents

In 1997, the JWC authorized preparation of an Alternate WaterSupply Study to evaluate the feasibility of developing a source ofwater to augment or replace Minneapolis water. The 1997 studywas prompted by the need to begin negotiations on a new waterpurchase agreement. If Minneapolis either did not wish tocontinue the relationship or could not continue to offer watercost-effectively, the JWC was compelled to evaluate its options.The 1997 study concluded that an independent water supplysystem would be cheaper if Minneapolis water rates were toincrease by 130 percent over the 1997 rate of $0.89 per thousandgallons, or to $2.05 per thousand gallons.

The 1997 study concluded that conventional lime softening, theprocess currently utilized by Minneapolis, would be the mostcost-effective technology to implement in such a system. Itidentified the Prairie du Chien / Jordan aquifer as a logical sourceof water. This aquifer is an established, reliable source of water


with known water quality characteristics. This is the samegroundwater source utilized by the cities of St. Louis Park andPlymouth.

In the fall of 2001, Minneapolis expressed an interest in beginningnegotiations for a new long-term water purchase agreement. Inresponse, the JWC conducted a Peer Review to revisit severalimportant conclusions of the 1997 study. This Review indicatedthat projected Minneapolis water rates would exceed the cost ofdeveloping a new JWC water system. The review also indicatedthat softening using a reverse osmosis treatment technologywould be more cost-effective than conventional lime softening.The cost of membrane softening technology has decreased in theyears since the 1997 study. The Peer Review also confirmed thatthe Prairie du Chien / Jordan aquifer is a viable source of water.

Memorandum of Understanding. Negotiations withMinneapolis began in earnest in the fall of 2001. AMemorandum of Understanding was executed in March of 2002putting in place an interim rate of $1.89 per thousand gallons andfinancing amounts payable in excess of that rate for a one to twoyear period during which a final agreement is to be negotiated.

Study Goals and Objectives

The overall goal of this Study was to determine the most cost-effective way to continue to provide water of equal or betterquality to JWC customers.

To reach this goal, the Study had three major objectives.

• Assess the technical and economic feasibility ofdeveloping an independent water supply and treatmentsystem.

• Develop a Practical Water System Concept that wouldprovide water of similar finished quality to member citycustomers and use existing distribution and storageinfrastructure.


• Evaluate the ability of membrane treatment technology toprovide a finished water quality that meets federal andstate regulations and meets or exceeds customerexpectations.

Scope and Limitations

The Water System Feasibility Study evaluated the feasibility ofdeveloping a new, independent water system to serve JWCcustomers. If the three cities decide to continue to develop sucha system, many technical details would have to be finalized.

The Study included analyses of planning-level engineeringinformation related to such a system. Sources of water supplyand water demands were evaluated. Required modifications tothe water transmission system (large diameter pipelines) servingthe three cities were identified and evaluated. Raw and finishedwater qualities were profiled. Existing data was used whenavailable. Where necessary, conclusions and recommendationsfrom the 1997 Study were reviewed and re-evaluated.

The Study did not encompass typical master planning tasks.Rather than identify and evaluate numerous alternate systemconfigurations, the JWC opted to develop a single Base SystemConcept for detailed evaluation. This approach built on thedetailed alternatives evaluation that was conducted during the1997 Study.

The Study should not be construed to be a water system facilityplan. Locations of wells and treatment facilities as well aspipeline routes were not evaluated. Membrane piloting andgroundwater modeling was also not conducted. Finally, costinformation presented in this report includes appropriatecontingencies to reflect undeveloped design detail that wouldneed to be evaluated through facility planning and pre-designwork.


SECTION 3

WATER SUPPLY

TABLE 3-1 below summarizes the water supply analysis that was undertaken for thisstudy.

TABLE 3-1. Analysis Summary

Assumptions

Source of Supply • Proven, reliable source able to be permittedby the Department of Natural Resources

• Protected from Contamination

• Does not affect supplies of neighboringcommunities

• Able to be cost-effectively developed

Quality • Able to be cost-effectively treated to equal orbetter quality than Minneapolis treated water

Alternatives Screening

Surface Water Supply (Mississippi River) • Eliminated due to difficulties related todelivery, more rigorous regulations, andhigher treatment costs.

Mt. Simon Hinckley Aquifer • DNR moratorium on additional development

Franconia, Ironton, Galesville Aquifer • Possibly limited yield

Prairie du Chien / Jordan Aquifer(PDC/J)

• Proven, reliable, and able to be permitted bythe Department of Natural Resources

Conclusions and Recommendations

The Prairie du Chien / Jordan (PDC/J) Aquifer offers a proven, reliable source. Impacts onneighboring wells need to be evaluated in more detail.

PDC/J is protected from contamination by three or four confining layers. This also adequatelyprotects nearby surface waters.

PDC/J water quality is well known. St. Louis Park and Plymouth both utilize this source.


Raw Water Supply

Due to raw water delivery expense, more rigorous regulatoryrequirements, and higher treatment plant costs, surface watersources were eliminated in favor of groundwater as a potentialraw water supply. For the 1997 JWC Alternate Water SystemStudy, groundwater from the Prairie du Chien/Jordan (PDC/J)Aquifer was identified as the best available source. This 1997recommendation was confirmed in the present study.

The Prairie du Chien/Jordan (PDC/J) aquifer was identified as thebest source raw water source supply to serve a new JWC watersystem. FIGUREs 3-1 and 3-2 provide information relating to thecoverage and depth of the PDC/J Aquifer. In general, the aquiferis large and deep with a series of confining layers above the JWCarea. (Refer to FIGURE 3-2 and the arrow indicating the locationof the PDC/J aquifer relative to aquifers and confining layerslocated above it. These confining layers greatly reduce both thethreat of contamination and impacts to nearby surface waterbodies. In reviewing various potential groundwater sources, thesurficial drift aquifer was eliminated from consideration due topresent and possible contamination issues. A moratorium onadditional usage of the Mt. Simon Hinckley aquifer precluded thatsource from further consideration. The Franconia-Ironton-Galesville aquifer was also eliminated as a possible raw watersupply due to concerns about limited yield.

During the 1997 Study, well siting constraints were identified byemploying a computer-based groundwater model. This modelingeffort identified the following issues. For purposes of this Study,those conclusions and recommendations from the 1997 Studyremain valid.

• Well-spacing limitations of 1600-ft in the southern portionof the JWC area and 1900-ft in the northern portion of theJWC area.

• Limiting pumping rates of 1500-gpm per well


• Potential interference with existing neighboring wellsranging between 20-ft and 48-ft at 20.5 mgd, and rangingbetween 16-ft and 37-ft at 8 mgd. Lowering pumps inexisting neighboring wells is likely required.

FIGURE 3-1. Prairie du Chien/Jordan Aquifer (from 1982 USGS Atlas)

The 1997 Study did not investigate the amount of water availablefor use according to the Minnesota Department of NaturalResources (DNR) permitting process. Based on present quantitiesof DNR-permitted PDC/J aquifer water in communities adjacentto the JWC, there appears to be an abundance of water availablefor further development. TABLE 3-2 shows the amount of waterpermitted and used by communities neighboring JWC that rely onthe PDC/J aquifer.


FIGURE 3-2. Prairie du Chien/Jordan Aquifer


TABLE 3-2. Groundwater Use Permits for Communities Neighboring JWC

Unused CapacityCommunity Permitted Amount (mgy) Amount Used (mgy) mgy mgd

Plymouth 50,400 3596.6 46,803.4 128.2Edina 54,000 2674.8 51,325.2 140.2St. Louis Park 35,000 2498.7 32,501.3 89.0TOTAL 357.4

Source: Minnesota Department of Natural Resourcesmgy = million gallons per yearmgd = million gallons per day

Based on present and permitted usage for those communitiesadjacent to the JWC that rely on the PDC/J aquifer, it appears thatthere is abundant water available for use by the JWC. With anaverage of 357.4 mgd unused capacity, JWC maximum dailydemand represents 5.3-percent of the total unused capacityattributed to Plymouth, Edina, and St. Louis Park.

Discussions with the DNR indicated likely support for JWC use ofthe PDC/J Aquifer, noting sufficient aquifer yield and wateravailability in this area. DNR staff indicated that updatedgroundwater modeling would be required to assess the impacts ofnew wells upon both aquifer levels and upon neighboring welllevels.

According to the DNR, the City of Minneapolis has recently beenencouraged to consider reliance upon the PDC/J Aquifer as anemergency back-up supply. Consequently, the prospect of a newJWC system that treats water from the PDC/J Aquifer is likely to beamenable to the DNR since it provides additional water supply ina part of the metropolitan Twin Cities that does not rely heavilyupon the aquifer.

Raw Water Quality

The 1982 United States Geological Survey (USGS) groundwateratlas provides additional information on the PDC/J Aquifer. In


general, PDC/J water in Minnesota exhibits levels of highhardness, solids, iron, manganese. This water quality data isprovided in TABLE 3-3.

A survey of several wells serving communities surrounding theJWC indicates the raw water quality that can be expected innewly developed PDC/J wells. Raw water quality data from St.Louis Park and Plymouth, both of whom rely on the PDC/J aquiferas a raw water supply, was collected for consideration. Thesedata are summarized in TABLE 3-4.

TABLE 3-3. Prairie du Chien/Jordan Aquifer Water Quality

Property or Constituent Unit Range Average # Analyses

Total Hardness mg/L as CaCO3 150 - 660 280 215Alkalinity2 mg/L 191 - 550 319 182Calcium mg/L 26 - 290 70 226Magnesium mg/L 11 - 51 26 194Iron mg/L NAManganese mg/L NAChloride mg/L <1 - 35 3.6 227Sulfate mg/L 14 - 480 28 227Total Solids mg/L 165 - 1000 311 187PH pH units 6.6 - 8.4 7.63 215Fluoride mg/L 0.1 - 0.5 0.2 217Nitrate (as N) mg/L <0.01 - 29 2.34 93Sodium mg/L 1.4 - 110 8.7 227

1USGS Groundwater Atlas, 1982 and 1983 data2Represented as bicarbonate in USGS data3Median


TABLE 3-4. Raw Water Quality for St. Louis Park and Plymouth

Property or Constituent Unit St. Louis Park1 Plymouth2

Total Hardness mg/L as CaCO3 300 - 330 240 - 340Alkalinity mg/L 270 - 311 260 - 340Calcium mg/L as CaCO3 180 - 202 100 - 220Magnesium mg/L as CaCO3 120 - 128 40 - 140Iron mg/L 0.73 - 4.8 0.1 - 1.4Manganese mg/L 0.08 - 0.12 0.02 - 0.66Chloride mg/L 8 – 13 2 - 13Sulfate mg/L 26 – 30 <5 - 10Total Solids mg/L 320 – 353 260 - 380pH pH units 7.2 - 7.3 7.0 - 7.8Fluoride mg/L 0.18 0.16 - 0.233

Nitrate (as N) mg/L <0.1 <0.1Sodium mg/L 2.5 - 7.9 3.21 - 4.63

Radon pC/L 189 – 327 not available

1Data provided by St. Louis Park Utilities for PDC/J (and St. Peter) Aquifer2Data provided (1982-1997) by Plymouth Sewer and Water for Water Supply wells (1-9)3Plymouth fluoride and sodium data for wells 1-6


The PDC/J Aquifer is able to provide water in sufficient quantityand of a readily treatable quality for a new JWC Water System.The use of the PDC/J Aquifer for a JWC system is furthersupported when considering the availability, quality, andproximity of other groundwater and surface supplies. The use ofthe PDC/J Aquifer and effect of this use on surrounding supplieswould require validation with groundwater modeling. Thequality of water is well characterized, but would be furtherdocumented during pilot testing of membrane softeningtechnologies.

One or two PDC/J Aquifer well fields may be developed. Wellfield siting, spacing, and configurations would be constrained bythe following factors. These issues would need to be evaluatedduring groundwater modeling beyond the scope of this Study.


• 12-wells @ <1500-gpm (6 serving each treatment facility)

• Well spacing between 1600-ft to 1900-ft

A “basis of design” water quality matrix is summarized in TABLE3-5.

TABLE 3-5. JWC Raw Water Quality—Base Plan for Feasibility Study

Property / Constituent Unit JWC System

Total Hardness mg/L as CaCO3 300Alkalinity mg/L 300Calcium mg/L as CaCO3 200Magnesium mg/L as CaCO3 100Iron mg/L 1.5Manganese mg/L 1Chloride mg/L 15Sulfate mg/L 30Total Solids mg/L 350pH pH units 7.0-7.8Fluoride mg/L 0Nitrate (as N) mg/L <1Sodium mg/L 10Radon pC/L 350


SECTION 4

WATER DEMAND ANDCONSERVATION

TABLE 4-1 below summarizes the water demand analysis that was undertaken for thisstudy.

TABLE 4-1. Water Demand and Conservation Analysis Summary

Assumptions

Demand • JWC uses 7.8 million gallons of water per day(mgd) and 2.85 billion gallons per year.

• Maximum daily demands have averaged 21mgd over the past five years.

• Future in-fill development likely to requiresome additional system capacity.

• The JWC’s historical maximum daily demandwas 27 mgd in June,1998. Similar hot, dryconditions since that time have not replicatedthis extremely high demand.


• JWC should size treatment facilities for 22 mgd, expandable to 24 mgd.

• JWC storage facilities are sufficient to provide additional capacity during extendedhigh-demand periods. (This has been confirmed by hydraulic modeling.)

• Conservation may play a role in tempering maximum daily demands.

• Building on JWC policy, a conservation program should be developed that includespublic education and phased drought restrictions (sprinkling restrictions and bans).

Historical Water Demands

As part of this Water System Feasibility Study, historical JWCwater demands were examined. In sizing new well field(s) and


water treatment facilities, it is critical that the future demand forwater by the three JWC member cities be estimated.

During hot, dry weather in June of 1988, the JWC purchased 27mgd of water from Minneapolis in a single day. Similarconditions since that time have not resulted in similar maximumdaily demands. This suggests that operational considerations mayhave exacerbated unusually heavy sprinkling demands, resultingin an unusually high draw from Minneapolis. In any event,maximum daily purchases from Minneapolis since that time havenot exceeded 22 mgd. FIGURE 4-1 below presents average dailywater demands for each month. This is based on average dailydata compiled for the past five years.

FIGURE 4-1 Average Daily Water Demands

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

Janu

ary

Febru

aryMarc

hApri

lMay

June Ju

ly

Augus

t

Sept

embe

r

Octobe

r

Novem

ber

Dece

mber

Month

Mill

ions

of

Gallo

ns


Projected Future Water Demands

As part of this Water System Feasibility Study, projected futurewater demands were developed and used to determine requiredcapacities of the treatment facilities and well fields.

In developing such projections, the following assumptions weremade.

• The JWC service area is not expected to expand beyondexisting boundaries.

• There are no immediate or long-term opportunities toprovide water to neighboring communities, either on anemergency-only or wholesale basis.

• The population of the three JWC member cities is notexpected to grow over the next twenty years, except for asmall amount of in-fill development.

Based on these assumptions, TABLE 4-2 below presents assumedfuture water demands.

TABLE 4-2. Projected Future Water Demands

Millions ofGallons

Average AnnualPercentage

Increase

2002Average Daily Demand 7.8Maximum Daily Demand 22.0

2022Average Daily Demand 8.5 0.44%Maximum Daily Demand 24 0.44%


Water Conservation

For many cities and utilities, water conservation has developedinto a powerful tool to help manage increasingly scarce watersupplies. At its core, water conservation programs strive tomodify customers’ water consumptions habits through education,economic incentives, and other drought management policies.

Development of a comprehensive water conservation programwas beyond the scope of this Water System Feasibility Study.However, evaluating the feasibility of a new water supply shouldnecessarily address the use of water conservation tools to reducewater demand under drought conditions.

An effective tool to conserve water is to create an incentive forcustomers to reduce both inside and outside uses of water. Toreduce inside uses of water, showerhead and faucet restrictors,water-conserving washing machines, and low-flow toilets havebecome commonplace in many communities. Modifying insidewater-using behavior through public education is also effective.

Outside uses of water may be reduced through use of water-saving devices, but public education on sprinkling practices andwater-conserving landscaping is often the most effectiveconservation tools.

During the spring of 2002, the Minnesota Department ofTransportation was reconstructing that portion of State Highway100 located directly above the 36-inch water main deliveringwater to the JWC. A temporary shut-down of the main wasscheduled for early May. An analysis of historical water demandsin early May indicated that occasionally an extended hot, dryperiod may be experienced. As a result, the JWC adopted apreliminary Temporary Water Emergency policy in case hot, dryweather occurred during the shutdown period.

The Temporary Water Emergency policy included restrictions incase water reserves were depleted.


Level 1 Restriction. Residents with street numbers ending in anodd number are restricted to sprinkling, car washing and otheroutdoor water uses on Tuesdays and Saturdays. Residents withstreet numbers ending in an even number are restricted tosprinkling, car washing and other outdoor water uses onWednesdays and Sundays.

Level 2 Restriction. All residents are prohibited from sprinkling,car washing and other outdoor water uses until further notice.

Fortunately, these measures were not required and theconstruction work was completed without incident. This event,however, points to the fact that conservation policies andprograms are a part of modern utility management.


SECTION 5

WATER TREATMENT

TABLE 5-1 below summarizes the water treatment analyses that were undertaken forthis study.

TABLE 5-1. Water Treatment Analysis Summary

Assumptions

Source Water Quality • PDC/J aquifer water characterized by highhardness, iron and manganese.

Finished Water Quality • Hardness Below 75 mg/L

• Alkalinity Below 50 mg/L

• Iron and Manganese Below 0.05 mg/L

• Turbidity Below 0.1 NTU

• pH 7.5 to 8.5

Alternatives Screening

Treatment Technology • Conventional Lime Softening

• Membrane Softening


• Membrane softening is more cost-effective, particularly for new facilities.

• Membrane softening facilities require smaller buildings.

• The need for iron and manganese filtration prior to membrane softening should beevaluated during piloting of the membranes.

Minneapolis Water Works

The Minneapolis Water Works presently withdraws water fromthe Mississippi River to produce drinking water. Water


production averages between 60 and 70-million gallons per day(mgd). Peak summer production approaches 180 mgd.

Raw Mississippi River water is pumped to the Fridley SofteningPlant, where the following processes are employed:

• activated carbon (and potassium permanganate) additionfor taste and odor control;

• lime addition for softening;

• alum addition for color removal;

• precipitator upflow clarifiers for solids settling andremoval; and

• carbon dioxide addition for pH control.

From the softening plant, clarified and softened water ispumped to one of two filtration plants for further treatment,including the following processes:

• coagulant (ferric chloride) addition, mixing for color andsolids removal;

• pre-filtration chloramination with chlorine and ammonia;

• flocculant settling and removal;

• gravity filtration; and

• post-filtration chloramination with chlorine and ammonia.

In addition to the treatment processes noted above, fluoride isadded to the water to achieve benefits associated with publicdental health. An ortho/polyphosphate blend is added to finishedwater to minimize corrosion potential.

Water provided by Minneapolis, as reported by the Water WorksDepartment, exhibits a softness of 75-mg CaCO3 /L (calciumcarbonate per liter). Minneapolis conducted a Treatment ProcessFeasibility Study (1997) that reported its finished water quality


goals. These are summarized, as presented in the Minneapolis1997 Study, in TABLE 5-2.

TABLE 5-2. Minneapolis Finished Water Quality Goals.

Parameter Goal

Hardness (total as CaCO3) 75 mg/LAlkalinity (total as CaCO3) 50 mg/LTurbidity <0.1 NTUpH 8.7

Source: Minneapolis Water Works

Water Treatment Requirements

Raw Water Quality. Water from the Prairie-du-Chien/Jordan(PDC/J) Aquifer is abundant and would require treatment forhardness, iron, and manganese to achieve finished water qualitycomparable to or better than that provided by Minneapolis.Hardness, iron, and manganese in drinking water supplies areconsidered secondary contaminants, which means that there areno health-related concerns but aesthetically problematic.

The PDC/J aquifer has received significant study and its waterquality and quantity is well understood. The 1982 United StatesGeological Survey (USGS) groundwater atlas offers broadinformation on the PDC/J aquifer and indicates that it underliesthe Twin Cities metropolitan area at depths between 800-ft and900-ft. Further, it generally contains lesser average levels ofmeasured water quality constituents than other areas of theaquifer (e.g., Iowa or Wisconsin).

A survey of area PDC/J aquifer water wells indicates the rawwater quality that can be expected to supply a new JWC watersystem. Raw water quality data from St. Louis Park andPlymouth, both of whom rely on the PDC/J aquifer as their rawwater supply, was collected to confirm the results of the JWC’s1997 Report.


The raw water quality of wells in St. Louis Park and Plymouth (seeSection 3) that serve as the basis for subsequent evaluation ispresented in TABLE 5-3.

TABLE 5-3. JWC Raw Water Quality—Basis for Feasibility Study

Property or Constituent Unit JWC System

Total Hardness mg/L as CaCO3 300Alkalinity mg/L 300Calcium mg/L as CaCO3 200Magnesium mg/L as CaCO3 100Iron mg/L 1.5Manganese mg/L 1Chloride mg/L 15Sulfate mg/L 30Total Solids mg/L 350pH pH units 7.0-7.8Fluoride mg/L 0Nitrate (as N) mg/L <1Sodium mg/L 10Radon pC/L 350

Finished Water Quality. Water provided by Minneapolisexhibits softness of 75 mg/L. This is 17 percent lower than 90-mg/L as assumed in the 1997 Study and indicates the need for a20-percent increase in treatment capacity. Minneapolisconducted a Treatment Process Feasibility Study (1997) thatreported its finished water quality goals. Finished Water Qualitygoals of Minneapolis and any new JWC system are presented inTABLE 5-4.


TABLE 5-4. Finished Water Quality Goals.

Parameter Minneapolis Goal JWC Goal

Hardness (total as CaCO3) 75 mg/L 75 mg/LAlkalinity (total as CaCO3) 50 mg/L 50 mg/LTurbidity <0.1 NTU <0.1 NTUpH 8.7 7.5 to 8.5Iron not identified1 <0.05 mg/LManganese not identified1 <0.05 mg/L

1Iron and manganese are effectively removed as part of the lime softening process

Regulatory Requirements. Hardness, iron, and manganese indrinking water supplies are considered secondary contaminants,which means that they are not health-related concerns, but ratheronly aesthetically problematic. Unlike a surface water supply(e.g., Mississippi River), there are no primary contaminants ofconcern with the PDC/J aquifer. Consequently, treatment andregulatory requirements associated with any new plant are greatlyreduced with reliance upon the PDC/J Aquifer when compared toa surface water supply.

The United States Congress enacted the Safe Drinking Water Act(SDWA) in 1974. This act gave the Environmental ProtectionAgency (EPA) authority to establish contaminant standards fordrinking water supplies. The SDWA required EPA to establishprimary and secondary regulations for health-related andaesthetics-related contaminants, respectively. The SDWA gaveEPA the authority to delegate primary enforcement responsibilities(or primacy) to individual states so long as their adopted drinkingwater regulations are at least as stringent as the federal standards.Minnesota’s drinking water regulations are referenced in MNRules Chapter 4720 and enforced by the Minnesota Departmentof Health (MDH).

Current and anticipated drinking water regulations governingfinished water quality from a JWC groundwater supply aresummarized in TABLE 5-5. It is anticipated that finished water


from a new JWC system would be in full compliance with presentand future water quality standards.

In the State of Minnesota, groundwater use is regulated by theMinnesota Department of Natural Resources (DNR). Finishedwater quality is regulated by the Minnesota Department of Health(MDH). DNR and the MDH staff were interviewed for this Study.The DNR provided the following comments regarding a new JWCsystem:

• Groundwater modeling would be required to evaluate theuse of the PDC/J aquifer and the impact of this use onsurrounding wells and resources.

• A new JWC system could effectively “back-up”Minneapolis’ supply. This may be something encouragedby the DNR.

• Permitting is not expected to be a problematic orexhaustive process.

According to MDH, a new JWC system would not require pilottests since there are no concerns relating to primarycontaminants.


TABLE 5-5. Regulatory Considerations

Regulation Comment

PresentNational Primary DrinkingWater Regulations (NPDWR)

Trihalomethane (THM), Arsenic, and Radionuclides

Phase I Standards 8 Volatile Organic Chemicals (VOCs), benzene, trichloriethylene

Total Coliform Rule Total Coliforms, Fecal Coliforms, E. coli

Lead and Copper Rule Lead and Copper, Corrosivity

Phase II Standards 17 Synthetic Organic Chemicals, Inorganic Chemicals, and 10Volatile Organic Chemicals

Phase V Standards 15 Synthetic Organic Chemicals, 5 Inorganic Chemicals, and 3Volatile Organic Chemicals

Consumer ConfidenceReports (CCR)

Annual Water Quality Report to Customers

PendingGroundwater Rule Specifies the appropriate use of disinfection and stresses multiple-

barrier approach, including best management practices, sourcewater monitoring, and contamination control.

Arsenic Revised MCL of 10 mg/L.

Radionuclides Includes Radium, Uranium, Alpha/Beta/Photon emitters. Setsnew Uranium MCL of 30 ug/L. Previous MCLs for other subjectconstituents maintained with revised monitoring requirements forcombined radium-226 and radium-228, gross alpha particleradioactivity, and beta particle and photon radioactivity.

Radon Two options proposed. Base MCL of 300-pCi/L with alternate of4000-pCi/L if multi-media mitigation (e.g., air contamination)considerations are made.

Stage 1Disinfectants/DisinfectionByproducts (D/DBPs) Rule

Effective 2004 for groundwater systems. Addresses D/DBP levelswith MCLs established for haloacetic acids, chlorite, and bromate.

Sulfate EPA currently evaluating necessity of sulfate regulation.

Drinking Water Contaminant Additional IOCs, SOCs, VOCs, pesticides.


Water Treatment Technologies

Membrane softening and lime softening technologies are the mosttechnically and economical viable technologies to softengroundwater. Membrane softening and Conventional LimeSoftening (CLS) were considered as part of the 1997 Study, withCLS forwarded as the most economically feasible alternative for anew JWC system. Although CLS is a proven softening technologythat would adequately serve the JWC, there were several factorsthat warranted reassessment of membrane softening technologiesas part of a new JWC water system. This included optimizingassumed operating conditions (e.g., plant size with respect toblending), and cost validation.

Conventional Lime Softening. High hardness, dissolved iron, andmanganese can be effectively removed from water supplies usinga conventional lime softening (CLS) treatment process. Untilapproximately 10-years ago, the CLS process had beenimplemented by most water producers to soften groundwater inmunicipal-scale applications, especially in the Midwestern USand Florida. CLS is comprised of four basic treatment processes,including:

• Aeration—aeration is the removal of carbon dioxide(increase pH) and oxidation of dissolved iron andmanganese to solids particles that can be settled or filteredin subsequent downstream processes. Aeration is typicallyachieved with a system that runs water in a directioncounter to air, maximizing contact between water and air.

• Solids Contact Clarifiers—lime is added to the waterdownstream of aeration to react with those constituentsthat make water “hard”, dissolved calcium andmagnesium. The reaction of lime with calcium andmagnesium yields a solid particle that is removed viaflocculation and gravity settling. Flocculation is enhancedby the addition of iron salt that coagulates solid particles.Dissolved iron and manganese which is oxidized to solids


particles during aeration are also removed during solidscontact.

• Recarbonation—treated water from the solids contactclarifiers exhibits a high pH. During recarbonation, thewater’s pH is lowered to more stable levels that are notprone to scaling in subsequent treatment process and thedistribution system.

• Filtration—not all suspended particles are removed withsolids contact clarification. Filtration is employed toremove smaller particles that remain after solids contactclarification, and consists of water flowing through dual(e.g., vertically stratified) media at controlled rates. Duringconventional lime softening of low-solids groundwater,filtration removes precipitates of remaining calcium,magnesium, iron, and manganese.

Following lime softening, disinfection is required to mitigatemicrobiological activity within the distribution system. This isoften achieved with the addition of chlorine (Cl2). Finished wateris also often augmented with fluoride to pride benefits associatedwith preventive dentistry. For the JWC, the conventional limesoftening process under consideration as part of this FeasibilityStudy includes two-stage conventional lime softening,disinfection, and fluoridation. This process schematic ispresented is FIGURE 5-1.


FIGURE 5.1

Recommended Design Standards for a JWC CLS Plant areprovided in TABLE 5-6 and are derived from various sourcesincluding Ten-States Standards from the Great Lakes UpperMississippi River Board of the State Public Health andEnvironmental Managers (1992), Minnesota Department of Health(MNDOH) Statutes, and Integrated Design of Water TreatmentFacilities (Kawamura, 1991).


TABLE 5-6. Lime Softening—Recommended Design Standards

Unit process Design Standard Comment

Aeration ß Suggested when CO2 >10 mg/L

ß 1 to 5 gpm/sf total tray area

ß Air to water ratio of 100:1

Solids Contact Clarifiers ß Rapid mix basins with <30 secondsdetention

ß Flocculation >30 minutes

ß Detention >60 minutes

ß Weir loading 20 gpm/sf

ß Upflow rate 1.75 gpm/sf

Recarbonation ß Depth >7.5 feet

ß >3 minute mixing zone

ß 20 minutes total detention

Filtration ß Filtration rate of 5 gpm/sf

ß Effective grain size 0.45 to 0.55mm

ß Washwater rate of 15 gpm/sf for15 minutes

Disinfection ß Chlorine residual of 0.2 to 2.0mg/L in distribution system

Fluoridation ß Fluoride @ ~1 mg/L in distributionsystem

MDH (4720.3940);

10-States Standards(1992) and Kawamura(1991)

Membrane Softening

Membrane softening treatment, including reverse osmosis andnanofiltration technologies, for hard groundwater supplies hasrecently become a more proven and cost-effective technology forsoftening municipal groundwater supplies. Membranes generallyare used to separate particles or solid materials from liquid—withdifferent membrane types employed depending upon the size ofparticle solid to be separated. FIGURE 5-2 presents the available


filtration and membrane technologies for varied targetcontaminants and applications.

FIGURE 5-2.

Angstrom Units (Log Scale)

Relative Size of Common Materials

Process For Separation

Approx. Molecular Wt. (Saccharide Type-No Scale)

Atomic Radius Aqueous Salts

Metal Ion Sugar Synthetic

Dye Albumin Protein

Carbon Black Endotoxin/Pyrogen

Virus Tobacco Smoke

Colloidal Silica

Paint Pigment Bacteria

Blue Indigo Dye Pesticide Herbicide

Gelatin Asbestos Latex/Emulsion

Yeast Cells Pin Point

A.C. Fine Test Dust Milled Flour

Red Blood Cells Pollen

Coal Dust Crypt- ospor- idium Giardia

Cyst

Beach Sand Granular

Activated Carbon Ion Ex. Resin Bead

Human Hair Mist

REVERSE OSMOSIS (Hyperfiltration)

NANOFILTRATION ULTRAFILTRATION MICROFILTRATION PARTICLE FILTRATION

2 7 8 5 3 2 6

8 5 3 2 10 10 5 8 10

5 3 2 4 10 8000 3000 5000

500,000 800 1000 300 500 80 100

50 30 200 100,000 20,000 10,000 2000 8 10

5 3 2 200 100 1000 20

Membrane softening is achieved with either reverse osmosis ornanofiltration, depending on the raw water quality and thedesired salt rejection of various target species. Full-scalemembrane softening is a mature technology with many successfulreference plants. Over 100 installations in the US providetreatment for “hardness” constituents such as dissolved salts orsolids1. Costs for membrane softening treatment plants havedecreased in recent years due to membrane technologydevelopment and supplier competition. A number of membranemanufacturers offer proven technologies for drinking watersoftening applications, including, but not limited to Koch,Hydranautics, US Filter, Osmonics, and Ionics.

1 Mallvialle, J.; et al, 1996, Water Treatment Membrane Process—AWWARF, LdE, and WRC; McGraw-Hill, New York.


By blending with un-softened groundwater, membrane softeningtechnology becomes more cost-competitive than was originallyconcluded in the 1997 Report. Using a reverse osmosis (RO)technology that removes more dissolved calcium and magnesiumthan nanofiltration, a raw water hardness level of 300 mg/L asexpected form the PDC/J Aquifer water and a finished waterhardness level of 75 mg/L means that approximately 15-percent ofthe finished water can bypass membrane softening after receivingtreatment for iron and manganese removal. In other words, only85-percent of the raw water would require membrane (RO)softening treatment to produce water of similar quality to presentMinneapolis water.

With a peak water demand of 22 mgd, the required capacity ofthe membrane softening plant would be 19 mgd, with 3 mgdbypassed during peak demand conditions. Under averageconditions, 7 mgd would receive membrane softening treatment,with 1 mgd bypassed. By contrast, a 22 mgd peak designcapacity and 8 mgd average design capacity would be requiredfor a conventional lime softening plant since all hardness cannotbe removed during the treatment process. Further, membranesoftening facilities may be easily expanded if piping and buildingsare constructed to allow the installation of additional membranesin the future.

The quality of membrane softened water would be similar inhardness but of better quality with respect to other constituents.In either treatment scenario, finished water quality would becompatible with JWC’s distribution and storage system. Watertreatment relying upon membrane softening would include thefollowing process components:

• Iron and Manganese Treatment—numerous treatmentalternatives are used for iron and manganese removal.Most often, treatment includes oxidation of dissolved ironand manganese to solids particles. Once oxidized to theirprecipitate forms, iron and manganese are typicallyremoved via filtration. With removal of iron andmanganese upstream of membrane softening, there is


potential for membrane fouling and considerable reductionin treatment efficiency.

• Membrane Softening—Membranes are comprised of thinfilm composites that are of spiral wound or hollow fiberconstruction. Feed water is driven under pressure throughthe membrane whereby solids and solutes, such ascalcium and magnesium that contribute to hardness, infeed water are removed at the membrane surface. Treatedwater is collected for production. Membrane filteredwater, or reject, is continually or occasionally removeddepending upon system configuration. See FIGURE 5-3 fora visual presentation of a typical RO membrane.

FIGURE 5-3. RO Membrane (spiral-wound)

from Water Treatment Membrane Processes, 1996, McGraw-Hill

As noted above for CLS, membrane softening would includedisinfection to mitigate microbiological activity within the


distribution system. Finished water is also augmented withfluoride as a preventive dentistry measure. A process schematicfor membrane softening is presented in FIGURE 5-4.

FIGURE 5-4. Membrane Softening Process Schematic (for JWC).

Recommended Design Standards for a membrane softeningfacility are provided in TABLE 5-7 and are derived from varioussources including Ten-States Standards from the Great LakesUpper Mississippi River Board of the State Public Health andEnvironmental Managers (1992), Minnesota Department of Health(MNDOH) Statutes, and Integrated Design of Water TreatmentFacilities (Kawamura, 1991).


TABLE 5-7. Membrane Softening—Recommended Design Standards

Unit process Design Standard Comment

Fe/Mn Removalfiltration

ß Permanganate feed

ß Filtration rate of 3 to 5-gpm/sf

ß Washwater rate of 8 to 10-gpm/sf

membrane softening ß 15-gpd/sf

ß Validation during pilot studies

disinfection ß Chlorine residual of 0.2 to 2.0mg/L in distribution system

fluoridation ß Fluoride @ ~1 mg/L in distributionsystem

MNDOH (4720.3940);

10-States Standards(1992); Kawamura(1991); and AWWARF(1996)

Comparison of CLS and Membrane Softening

Non-cost factors. Advantages and disadvantages of membranesoftening are presented in TABLE 5-8.

Costs. Capital and O&M cost estimates have been developed forCLS and membrane softening (reverse osmosis). These costs arepresented in TABLE 5-9 and TABLE 5-10 and are derived from anumber of sources as indicated. The capital costs are based on atraditional design-bid-build delivery method and do not includemark-ups associated with engineering, legal, and administrativeservices required for project implementation. Costs associatedwith contractor overhead and profit are also not included. Costsbelow were developed based on a single 19 mgd plant.


TABLE 5-8. Comparison of CLS and Membrane Softening Treatment Technologies

Advantages Concerns

Conventional Lime Softening

ß Proven technology

ß Known application (e.g.,Midwest Installations)

ß Space requirements (~3-acres for 19mgd plant)

ß Chemical handling

ß Waste disposal (lime sludge—solids)

ß Greater operator requirements—time andsophistication.

ß Greater disinfectant demand

ß Difficult to expand

ß Redundancy more costly

Membrane Softening

ß Space requirements (~1.5-acresfor 19 mgd production)1

ß Proven technology

ß Easily automated—lessensoperator requirements

ß Decreased disinfectant demand

ß Modular—easily expanded

ß Chemical handling

ß Energy usage

ß Waste disposal (reject--LIQUID)

ß Potential for costly repairs withoperations mistakes

1Based on 19 mgd finished water production, including 16 mgd RO Membranes and 19 mgd Fe/Mn removal with greensand filtration


TABLE 5-9. Estimated Cost of Conventional Lime Softening (19 mgd Facility)

Component Cost Estimate Comment

Capital Sitework/yard piping $ 2,000,000 Aerator 300,000 Solids contact clarifiers 3,000,000 Recarbonation 1,300,000 Gravity filters 7,100,000

Estimated based on materialtake-off and EPA manual figures

Washwater and solids handlingsystem

900,000 Equalization tank, EPA-manualpump station to interceptor

Chemical feed systems 1,750,000 Building 2,300,000 300-ft x 150-ft building Electrical and instrumentation 1,900,000 ~10-precent of project costs TOTAL $20,500,000

O&M Labor $ 600,000 8-FTE Energy 350,000 800-hp equivalent Chemical 540,000 Primarily lime and carbon

dioxide Solids handling 1,250,000 Industrial sewer rate Maintenance 280,000 TOTAL $3,020,000


TABLE 5-10. Estimated Cost of RO-Membrane Softening (19 mgd Facility)

Component Cost Estimate Comment

Capital Sitework/yard piping $ 1,500,000 Chemical feed 1,300,000 Membrane equipment 7,900,000 14 mgd, references include Morin

(1994), La Junta (2001) Greensand pressure filters 4,500,000 19 mgd, 10 pressure vessels and

associated piping/valving Washwater and solids handling 350,000 EPA-manual pump station to

interceptor Building 1,600,000 175-ft x 175-ft building Electrical and instrumentation 1,850,000 ~10-precent of project costs TOTAL $19,000,000

O&M Labor $ 450,000 6-FTE Energy 700,000 Includes membranes, solids and

finished water pumping. misc.plant load. References includeMorin (1994) and La Junta(2001)

Chemical 625,000 Primarily lime and carbondioxide. References includeMorin (1994) and La Junta(2001)

Solids handling 525,000 Industrial sewer rate Maintenance 340,000 Membrane replacement and

general plant needs. Referencesinclude Morin (1994) and LaJunta (2001)

TOTAL $2,640,000


Conclusions and Recommendation

Based on both non-cost and cost factors, membrane softeningappears to be the most cost-effective treatment alternative for anew JWC system. Membrane softening is less expensive than CLSwhen considering either capital cost or O&M cost. Additionally,the following non-cost factors support the recommendation ofmembrane softening as the treatment technology for a new JWCsystem:

Space Requirements: a membrane softening plant requires lessspace than a comparably-sized CLS plant. In JWC’s largelydeveloped and mature residential area, siting issues associatedwith new water system facilities more difficult with increasedspace requirements.

Scalable/Modular: the base components of a membrane softeningplant are smaller in scale than those associated with a CLS plant.In other words, membrane softening plants can be divided orexpanded with relative ease in comparison to a CLS plant.

By-Product Disposal: the CLS process produces significantquantities of lime sludge that requires handling and disposal. Bycontrast, the membrane softening process byproduct streamsconsist primarily of water and those constituents removed duringtreatment. Disposal of treatment stream byproducts, in the caseof a JWC system, is easier with membrane softening than for CLS.

Therefore, a base plan concept for a new JWC Water Systemincludes reliance upon membrane softening technology,including iron/manganese treatment, for production of finishedwater. The finalization of plant design is subject to pilot testingduring the any pre-design effort. The base plan identifies two 9.5mgd membrane softening plants, each located proximate to theground level reservoirs in Golden Valley and Crystal. A site planfor the proposed 9.5 mgd plants is provided in FIGURE 5-5.


SECTION 6

WATER DISTRIBUTION AND STORAGE

TABLE 6-1. Distribution and Storage Analysis Summary

Assumptions

Existing Facilities • Existing storage reservoirs (Crystal andGolden Valley) would be available for use.

• Three elevated water storage tanks provideadditional operating storage


• Existing storage reservoirs provide adequate storage under either continued waterpurchases from Minneapolis or a new JWC water system developed usinggroundwater.

• The existing transmission and distribution system is adequate to distribute water tocustomers, under either continued water purchases from Minneapolis or a new JWCwater system developed using groundwater.

• Additional raw water pipelines would be needed to collect raw water from well sitesand pump it to the treatment facilities.

The Joint Water Commission presently receives treated surfacewater from the City of Minneapolis. The water is delivered to oneof two JWC ground level reservoirs. Both reservoirs include highservice booster pumping stations through which water isdelivered into the JWC distribution system network of watermains and elevated storage tanks. A detailed listing of JWC watersystem components is provided in TABLE 6-2.


TABLE 6-2. JWC Water System Components

STORAGE Volume (gallons) Overflow Elevation (feet)

Crystal Reservoir 19,000,000 888.7Golden Valley Reservoir 9,000,000 910.5North Tower 500,000 1069Medicine Lake Tower 1,500,000 1069Golden Valley Tower 1,500,000 1069

BOOSTER PUMPSCrystal Reservoir Number of pumps 5 Rated capacity, each pump 4,500-gpm @ 200-ft TDH Firm capacity 18,000-gpm Number of stages/pump 3 Motor horsepower 300

Golden Valley Reservoir Number of pumps 5 Rated capacity, each pump 2,850-gpm @ 210-ft TDH Firm capacity 14,250-gpm Number of stages/pump 3 Motor horsepower 200

1997 Report

Previous planning and study efforts have employed CYBERNET™,a computer-based simulation model. This model was validated aspart of the 1997 Report to account for a 20.5-mgd systemdemand. As part the report, alternate water treatment plantlocations were assessed with respect to existing JWC facilities(e.g., pipes and reservoirs) and new facilities (e.g., wells andtreatment).


Four treatment plant locations were assessed, including:

• Begin Park (northwest)

• Crystal Reservoir (northeast)

• Golden Valley Reservoir (southeast)

• Golden Valley Water tower (southwest)

The 1997 Report concluded that supplying the JWC through asingle delivery point such as a new plant would result inundesirable pressure distributions throughout the system duringpeak demand. With this initial conclusion, the 1997 Reportrecommended one plant located near one of the reservoirs with alarge-diameter water main interconnecting these reservoirs. Thisconclusion was re-evaluated during the present Study. It wasdetermined that the JWC might benefit from two treatmentfacilities, each located near the large treated water reservoirs.This would provide some operational flexibility. Also, nointerconnecting main between the two reservoirs would benecessary.

The 1997 Report did not assess the adequacy of the presentstorage. Elevated storage tanks provide 3.5-million gallonsstorage for JWC, and an additional 28-million gallons storage isprovided by the ground level reservoirs in Golden Valley andCrystal.

Validation

Since the Cybernet ™ model has been employed on separateoccasions by two different parties, it is assumed that the results ofthe 1997 Report are valid for the present Study.

During the present Study, an analysis was completed to assessJWC’s operational storage requirements. This analysis concludedthat the present JWC storage is adequate for system demandsabove 20 mgd. In other words, no additional storage is necessaryshould the JWC operate a new water system


SECTION 7

ECONOMIC AND FINANCIAL FEASIBILITY

TABLE 7-1. Economic and Financial Analysis Summary

Assumptions

Financing • 20-Year Tax-exempt bonds issued at anaverage bond rate of 4.5 percent.

• User Charges support all the costs of the newsystem.

• No property tax revenues would be neededto support the new system.

• The three cities would support the new systemon a pro rata basis.

Conclusions

• A new water system can provide water for $2.28 per thousand gallons, replacing$2.34 per thousand gallons in cost projected to be paid to Minneapolis for treatedwater in 2005.

• Indicated savings 2005-7 are $1.62 million

• Annual savings beyond 2007 are projected to be just under $1 million, depending onfuture Minneapolis rates.

• This represents a return on investment of 3.6%

Cost Summary

TABLE 7-2 presents the capital and operating costs of the new facility. Capital costs,including construction, engineering, and administration, are assumed to total $45million. Annual costs are assumed to include debt service on $45 million in bondsand operations and maintenance.


TABLE 7-2. JWC WATER SYSTEM COST SUMMARY

Cost ($000)

Water Treatment Plant No. 1 17,200,000$ Water Treatment Plant No. 2 17,200,000 Wellfields and Pipelines 10,600,000

TOTAL COST 45,000,000$

Annual Debt Service 3,459,000$ Annual Operations & Maintenance Cost 2,975,000 Administrative Overhead 75,000

TOTAL ANNUAL COST 6,509,000$

Indicated Cost per Thousand Gallons (2.85 Bgal) 2.28$

Current (2002) Cost of Minneapolis Water 2.07$

Construction Costs assume 2003-4 dollars, O&M costs assume 2005 start-up.Annual debt service assumes 20-year bonds at an average bond rate of 4.5 percent.Annual O&M includes renewals and replacements.Indicated cost based on 2.85 billion gallons annual water purchase (1998-2001 average).Current cost of Minneapolis water is $2.07 per thousand gallons---$1.89 per thousand gallons is reflected in current JWC ratesand an additional $0.18 per thousand gallons is being deferred under interest-only financing from Minneapolis.


Capital Costs. TABLE 7-3, 7-4 present detailed capital costs of the dual treatmentfacilities and supporting wellfields.

TABLE 7-3. Dual Water Treatment Facilities Capital Costs (9.5mgd / 12 mgd)

Cost ($000)

Sitework / Yard Piping 900$ Fe/Mn Filters 2,300 Membrane Process Equipment 4,500 Washwater and Solids Handling 200 Chemical Feed Systems 700 Building 800 MCES SAC Fee 1,000 Electrical and Instrumentation 1,000 SUBTOTAL 11,400$

25% Undeveloped Design Details 2,900 25% Engineering, Permitting, and Admin. 2,900

TOTALS 17,200$


TABLE 7-4. Wellfield Capital Costs

Cost ($000)

6 - 900-ft Wells @ $250 1,500$ 1 - Well House 300 Raw Water Piping: 10,000 LF 12-in DIP @ $95/LF 1,000 Raw Water Piping: 4,000 LF 16-in DIP @ $130/LF 500 Raw Water Piping: 2,000 LF 24-in DIP @ $190/LF 400 SUBTOTAL 3,700$

25% Undeveloped Design Details 900 20% Engineering, Permitting, and Admin. 700

TOTALS 5,300$


Operations and Maintenance Costs. TABLE 7-5, 7-6 present annual operations andmaintenance costs of the new facilities.

TABLE 7-6. Wellfield Operations and Maintenance Costs

Cost ($000)

Labor 50$ Energy 100 Renewals and Replacements 75

TOTAL 225$

TABLE 7-5. Twin Water Treatment Facilities (2 @ 9.5 mgd / 12 mgd)Operations and Maintenance Cost

Cost ($000)

Labor 400$ Energy 700 Chemicals 625 Solids Disposal 525 Maintenance and Membrane Replacement 500 TOTAL 2,750$


Survey of Metro-Area Water Costs

Table 7-7 presents a survey of 2001 water rates.

TABLE 7-7. 2001 Residential Water Rate Survey(Softened and Unsoftened Water)

City Monthly Water Bill(7,500 Gallons)

SOFTENEDMinneapolis $ 18.10

Roseville 16.23New Hope 15.38

Golden Valley 15.00Crystal 14.92St. Paul 14.30

Bloomington 13.50Richfield 13.03

Eden Prairie 11.46White Bear Lake 8.40

UNSOFTENEDSavage $ 19.38

Prior Lake 12.38Apple Valley 11.96

Eagan 10.07Chanhassen 9.75

Edina 9.54Minnetonka 9.00

St. Louis Park 8.82Coon Rapids 8.60

Plymouth 7.32Maple Grove 6.75

Source: City of Bloomington and Telephone Survey