Town of Hinesburg - PDF document

Town of HinesburgWastewater Treatment F
Town of HinesburgWastewater Treatment Facility Upgrade/ExpansionPublic HearingOctober 28, 2020Source: “Hinesburg Wastewater Treatment Facility.” 4419’58”N 7307’26”W. Google Earth. Image Date: 6/9/2018.

Accessed: 7/22/2019History 1967: Origi
Accessed: 7/22/2019History 1967: Original aerated lagoon facility constructed1992: Phosphorus upgrade2009: Facility upgrade and expansion Age related issuesPlanned for an increase permitted flow from .250 to .308 mgdPermit increase wa

s not pursuedBackground2018 May: Town
s not pursuedBackground2018 May: Town issued Request for QualificationsJuly: A+E was selected following a Qualifications Based Selection processSeptember: Preliminary engineering study started that is funded by the State Clean Water S

RF program2020April: Final preliminary e
RF program2020April: Final preliminary engineering report was issued with proposed projectJuly: State funding details were finalizedTown established an active working group of elected Town officials, Town staff, and State representative

sPurpose and NeedsState issued a new Di
sPurpose and NeedsState issued a new Discharge Permit effective March 1, 2018. Lake Champlain Total Daily Maximum Load (TMDL) for phosphorus reduced from an annual limit of 608 lbsto 152 lbsNew water quality based limitation in the LaP

latteRiver for ammonia nitrogen to 3.5 m
latteRiver for ammonia nitrogen to 3.5 mg/l from June 1 September 30 Included a compliance schedule with a plan due by February 28, 2019Compliance with these limits is mandated by EPA and the StateThe existing aerated lagoon facility is

not able to consistently comply with th
not able to consistently comply with these lower limits without major upgradesBlower/Chemical Feed BuildingPurpose and Needs (Continued)Town wanted to explore an increase in capacity, and compare options and costs for both approaches.

By providing additional capacity, the n
By providing additional capacity, the new development will help to pay for the cost of the upgradesIncreased organic loading from industrial customers (breweries, food processing, etc.) limits future growth unless the facility is expan

dedThe upgraded facility will provide a
dedThe upgraded facility will provide a higher degree of treatment, thereby improving the water quality of the receiving waters. As an example, ultraviolet disinfection is planned, eliminating the use of chlorine.The new facility will b

e more energy efficient, constructed wit
e more energy efficient, constructed with sustainable materials, and will be have automated monitoring and control. Main Pump StationAerated LagoonsChemical Phosphorus RemovalDisinfection SystemProjected Wastewater Flows It

emFlows(gpd)Current Allocated FlowAverag
emFlows(gpd)Current Allocated FlowAverage Daily Flow (2016163,000Unconnected residential7,532Unconnected enterprise7,745Subtotal178,277Projected 20 Year FlowProposed135,139Total313,416Use325,000 Treatment Alternatives EvaluatedA

lternatives to Meet New Permit Requireme
lternatives to Meet New Permit Requirements @ 250,000 gpdNo. 1 Lagoon Upgrade with LEMINA plus Ballasted FlocculationAlternatives to Meet New Permit Requirements @ 325,000 gpdNo. 2 Sequencing Batch Reactor (SBR) with FiltrationNo. 3 Ana

erobic/Oxic(A/O) with FiltrationAlterna
erobic/Oxic(A/O) with FiltrationAlternative No.1 Lagoon Upgrades New HeadworksNew LEMNA system in Lagoons for ammonia removalTP removal with ballasted flocculationSludge storage tanksControl BuildingAlternative No.2 Sequencing Batch

Reactor with Filtration New HeadworksTw
Reactor with Filtration New HeadworksTwo new concrete SBR tanksNew Flocculation tankNew tertiary cloth media filtrationUltraviolet disinfectionSludge storage tanksControl BuildingNo.3 Anaerobic/Oxic(A/O) and Clarification with Filtrat

ionNew HeadworksTwo new A/O tanksTwo new
ionNew HeadworksTwo new A/O tanksTwo new secondary clarifiersNew tertiary flocculation tankNew tertiary cloth media filtrationUltraviolet disinfectionSludge storage tanksControl buildingWWTF ToursPurposeTo visit similar wastewater trea

tment facilities with the working group
tment facilities with the working group to view the treatment technologies, and ask questions of the operations staff.Facilities VisitedWaterbury, VT Aerated lagoons, ballasted flocculation.Hartford, VT QuecheeSequential batch reactors,

tertiary filtration, ultraviolet disinf
tertiary filtration, ultraviolet disinfection.South Burlington Bartlett’s Bay WWTFA/O process, tertiary filtration, ultraviolet disinfection. Geotechnical Investigation4 soil borings performed in January 2019Subsurface resultsVer

y soft gray clay (35’65’)Refus
y soft gray clay (35’65’)Refusal at ~70’Consolidation testing performedLong term consolidation of clays (3 to 3.5’)ImpactsSettlement expected of 18” to 42” over 50 yearsSubgrade Improvement AlternativesEva

luated subgrade improvementsWick DrainsS
luated subgrade improvementsWick DrainsSteel PilesSource: “Pile Foundation.” Civil Digitalhttps://civildigital.com/pilefoundationclassificationpilefoundationspileinstallationmethods/. Accessed: 7/22/2019Source: “Wick

Thinking.” Stuffhttp://www.stuff.c
Thinking.” Stuffhttp://www.stuff.co.nz/auckland/localnews/westernleader/9522556/Wickthinkingunderpinsmotorwayseawaterdrainageprocess. Accessed: 7/22/2019Subgrade Improvements Estimated CostsAlternatives Cost ComparisonOther A

lternatives ConsideredOutfall ExtensionW
lternatives ConsideredOutfall ExtensionWorked with State to model extending the existing outfall downstream to increase the ammonia limit.WWTF SiteDiscussed other sites to potentially avoid geotechnical issues.Proposed Project Phase I

Proposed Project Phase IIMain Pump Stati
Proposed Project Phase IIMain Pump StationNew HeadworksSequential Batch Reactors/Post EqualizationSource: “AquaAerobic Systems Ince..” Stuff. Accessed: 7/22/2019FiltrationChemical Feed/StorageUltraviolet DisinfectionProcess

Water Storage TankSludge Storage TanksCo
Water Storage TankSludge Storage TanksControl Building InPlant Pump StationEmergency GeneratorAbandon Existing LagoonsPhase IIEstimated Construction Cost Phase IItem DescriptionCostEstimate(ENR 11200)CostEstimate(ENR 11815)Sludge lag

oon/Lagoon #1 Remove dividing berm $28,
oon/Lagoon #1 Remove dividing berm $28,000$29,500Sludge lagoon Remove 2.5’ clay overburden $4,000$4,200Sludge lagoon/dividing berm Remove clay overburden $11,000$11,600Lagoon #1 Remove clay overburden $100,000$105,500Replace excav

ated soil with granular fill$230,000$242
ated soil with granular fill$230,000$242,600Fill interior of sludge lagoon$65,000$68,600Partial fill of lagoon #1$310,000$327,000Wick drains$477,000$503,000Subtotal15% ContingencyTotal$1,225,000$184,000$1,292,000$194,000$1,485,000Estim

ated Construction Cost Phase IIItem Des
ated Construction Cost Phase IIItem DescriptionCostEstimate(ENR 11200)CostEstimate(ENR 12200)Main Pump Station$243,540$265,200Lagoon Retrofits$403,700$439,600Headworks$861,300$938,000Biological/Clarification$2,061,400$2,245,000Tertiar

y $1,012,000$1,102,000Disinfection$564,3
y $1,012,000$1,102,000Disinfection$564,300$614,500Sludge Storage$449,240$489,200Control Building$1,134,100$1,235,000TotalUse$6,729,580$7,328,500$7,330,000Total Project Cost Summary and Bond AmountConstruction10% Construction contingenc

yEngineeringOther Costs AdministrationPe
yEngineeringOther Costs AdministrationPermit feesLegalShort term interestTotal Project Cost:$11,700,000Recommend Bond Amount:$11,700,000Primary Funding SourceVermont Watershed Investment Division (WID)Clean Water State Revolving Fund (

CWSRF)Loan Subsidy (50% up to $100,000 a
CWSRF)Loan Subsidy (50% up to $100,000 annually) for engineeringState Pollution Control Grant (Estimated at 17%)Additional subsidy at $500,000 per year, total $2,000,000Lake Champlain TMDL $2,000,000 in loan forgivenessLoan: 30 year ter

m @ 0% administrative fee Other Funding
m @ 0% administrative fee Other Funding SourcesUSDA Rural DevelopmentIncome survey was completed in late 2019. Since the median household income is higher than the State average, the Town does not qualify for a grant Northern Border R

egional Commission Offers grants of up t
egional Commission Offers grants of up to $1,000,000 for eligible infrastructure projects. US Department of Commerce Economic Development Administration (EDA)Provides grants in amounts from $100,000 to $3,000,000 Eligible infrastructure

projects that support economic developm
projects that support economic developmentFunding SummaryFunding SourceEstimated AmountCWSRF Engineering Subsidy$250,000Pollution Control Grant (17%)$1,989,000Additional Subsidy $2,000,000Lake Champlain TMDL Forgiveness $2,000,000CWS

RF Loan (0%, 30 years)$5,461,000Total Co
RF Loan (0%, 30 years)$5,461,000Total Cost$11,700,000Funding Summary0.2%46.6%CWSRF Engineering SubsidyPollution Control GrantAdditional SubsidyLake Champlain TMDL ForgivenessCWSRF Loan (0%, 30 yrs)Funding NotesAfter the grants,

subsidy and loan forgiveness, the total
subsidy and loan forgiveness, the total loan amount is $5,461,000. This 0% loan 30 year loan will save the Town approximately $4.5 M in interest expense over the 30 years. If the bond vote does not pass, several of these State funding s

ources may not be available for this pro
ources may not be available for this project after June 30, 2021, significantly increasing the future cost to the sewer customers. Impact on Sewer RatesThe annual loan payment for a 0%, 30 year term, will be approximately $184,000. Th

is 0% loan will save sewer customers abo
is 0% loan will save sewer customers about $95 per year. The Town plans to use about $75,000 per year in income collected from sewer connection and allocation fees to reduce the annual loan payment. Beginning in 2025, a typical resident

ial sewer customer will see an increase
ial sewer customer will see an increase in their sewer bill of about $90 per quarter for this project. As new sewer customers are connected from new development, it is expected that this projected increase will decrease. Project Sche