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FIRM OVERVIEW AND BACKGROUND <br /> Waimea Water Treatment Plant <br /> w Residuals Handling Improvements <br /> 4' ° HAWAII COUNTY,DEPARTMENT OF WATER SUPPLY,WAIMEA,HAWAII <br /> 141 <br /> Client Reference: <br /> 111, . Judy Hayducsko,Drinking Water State Revolving Fund,(formerly with Hawaii <br /> )ti" ` ' _@ - 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 <br /> handling system and the cost of off-site hauling of sludge,Carollo were conducted with DWS staff and representatives of the supplier <br /> of the membrane equipment to adjust backwash intervals and o <br /> was retained by the Department of Water Supply(DWS)to evaluate U) c <br /> reduce resulting backwash water volume.Sludge samples were also ? <br /> and implement residuals handling improvements at the WTP. <br /> collected to evaluate the effectiveness of alternative solids thickening (-j).; <br /> and dewatering processes. m- D <br /> N S, <br /> D <br /> N — <br /> • to I <br /> Carollo developed °- D <br /> 7, <br /> • <br /> a total plant solids �. b, <br /> balance to help the z <br /> DWS to determine • 4 , <br /> the root cause of Z Z <br /> 2 Fn <br /> residuals handling , o <br /> issues at the . L , ` ,, <br /> Waimea WTP. <br /> z <br /> z0 73 <br /> -n <br /> to m <br /> U) U) <br /> ( U) <br /> 0 <br /> zz <br /> � D <br /> CAROLLO / QUALIFICATIONS /JUNE 2024 7 <br /> \\io-bd-1\BD-DATA\Marketing\Pursuits\Client83(HON)\HawaiiCounty\EnvMgmtDept\On-Call FY24-25\Qua10624\PL.3-CommunityPlanning_CommPlanAssist\Indd\01_FirmOverview_PL3 <br />