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FIRM OVERVIEW AND BACKGROUND <br /> Waimea Water Treatment Plant <br /> . w Residuals Handling Improvements <br /> i'• - -,siii4; ' ' HAWAII COUNTY,DEPARTMENT OF WATER SUPPLY,WAIMEA,HAWAII <br /> -- Client Reference: <br /> . Judy Hayducsko,Drinking Water State Revolving Fund,(formerly with Hawaii <br /> `v. ;a- ',.%- , County Department of Water Supply) <br /> `. ;: ; 808.586.4258 / sdwb@doh.hawaii.gov <br /> The Waimea Water Treatment Plant(WTP)was constructed in the <br /> 1970s and currently produces an average of approximately 1.8 mgd of Project Highlights <br /> domestic water supply for the Waimea area.The WTP was originally • Total plant solids balance. <br /> designed as a conventional treatment facility with sedimentation <br /> basins and granular media filters.All residuals from the sedimentation • Process optimization to minimize waste streams. <br /> basin flow down and the filter backwash were discharged to an • Microfiltration backwash cycle evaluation. <br /> open concrete sludge reservoir until 2009,at which time a covered <br /> • <br /> solar dryer system was installed to dewater material accumulated Recommended long-term residuals <br /> at the bottom of the reservoir.In 2019 the conventional media filters handling improvements. <br /> were replaced by membrane microfiltration,resulting in a significant <br /> increase in backwash water volume and loading on the existing Summary of Scope <br /> residuals handling system. Initial tasks included the characterization of residuals flows and <br /> Currently,supernatant from the reservoir is returned to the head loads from the various unit processes,a comprehensive review of <br /> of the plant,while sludge from the bottom of the reservoir is either plant operations with a focus on process optimization to minimize <br /> pumped to the solar drying beds or removed off-site via a tanker waste streams,and assistance to DWS to provide incentives to new <br /> truck.Due to the strain on the capacity of the existing residuals sludge hauling contracts to increase removal effectiveness.Site visits o <br /> handling system and the cost of off-site hauling of sludge,Carollo <br /> were conducted with DWS staff and representatives of the supplier K <br /> of the membrane equipment to adjust backwash intervals and z o <br /> was retained by the Department of Water Supply(DWS)to evaluate =, c <br /> reduce resulting backwash water volume.Sludge samples were also < Z <br /> and implement residuals handling improvements at the WTP. < <br /> collected to evaluate the effectiveness of alternative solids thickening z o <br /> and dewatering processes. Z a <br /> D <br /> F) = <br /> P. <br /> Carollo developed '` Z Z <br /> '~ o <br /> a total plant solids K,d m <br /> balance to help they ° <br /> Z > <br /> DWS to determine 4 ` �, V�k. z <br /> the root cause of re- �.a �- Z <br /> 4 <br /> ` :ysdw . -G) -7° <br /> residuals handling ,- ., ,y ,,,, m <br /> 73 W <br /> issues at the <br /> t� "'h^e <br /> Waimea WTP. ; r. D <br /> - <. rc c. A — <br /> iiiiiciimiMiv <br /> DU) <br /> m m <br /> D < <br /> O N <br /> D ? <br /> N <br /> D <br /> v <br /> -I I <br /> O <br /> Z Am <br /> CAROLLO / QUALIFICATIONS /JUNE 2024 7 <br /> \\io-bd-1\BD-DATA\Marketing\Pursuits\CIient83(HON)\HawaiiCounty\EnvMgmtDept\On-Call FY24-25\Qua10624\PL.4-CommunityPlanning_Community\Indd\01_FirmOverview_PL4 <br />