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FIRM OVERVIEW AND BACKGROUND <br /> Waimea Water Treatment Plant <br /> , = / Residuals Handling Improvements <br /> - _ �'` - HAWAII COUNTY,DEPARTMENT OF WATER SUPPLY,WAIMEA,HAWAII <br /> 4 r Client Reference: <br /> w • Judy Hayducsko,Deputy Manager Engineer,Kauai County Department of Water, <br /> (formerly with Hawaii County Department of Water Supply) <br /> 808.245.5408 / jhayducsko@kauaiwater.org <br /> The Waimea Water Treatment Plant(WTP)was constructed in the the membrane equipment to adjust backwash intervals and reduce <br /> 197O's and currently produces an average of approximately 1.8 million resulting backwash water volume.Sludge samples were also <br /> gallons per day(mgd)of domestic water supply for the Waimea collected to evaluate the effectiveness of alternative solids thickening <br /> area.The WTP was originally designed as a conventional treatment and dewatering processes. <br /> facility with sedimentation basins and granular media filters.All <br /> o <br /> residuals from the sedimentation basin blow down and the filter Key Recommendations <br /> backwash were discharged to an open concrete sludge reservoir < <br /> until 2009,at which time a covered solar dryer system was installed The capacity,performance,and operation of the existing solar o <br /> dryer was also evaluated.Working closely with the vendor, _ <br /> to dewater material accumulated at the bottom of the reservoir.In a <br /> 2019 the conventional media filters were replaced by membrane recommendations were developed regarding system improvements D <br /> microfiltration,resulting in a significant increase in backwash water and allowable loading rates based on the percent solids which can -01 <br /> volume and loadingon the existingresiduals handlingsystem. effectively be removed from the lagoon. z <br /> Y z <br /> z <br /> Currently,supernatant from the reservoir is returned to the head Recommended long-term residuals handling improvements include m <br /> of the plant,while sludge from the bottom of the reservoir is either separation of the low-volume/high solids sedimentation basin blow <br /> pumped to the solar drying beds or removed off-site via a tanker down from the high-volume/low solids backwash water;increasing m <br /> truck.Due to the strain on the capacity of the existing residuals membrane backwash water intervals;and the installation of solids z <br /> —1 <br /> handling system and the cost of off-site hauling of sludge,Carollo thickening facilities. <br /> was retained by the Department of Water Supply(DWS)to evaluate <br /> and implement residuals handling improvements at the WTP. w <br /> O <br /> z <br /> D <br /> r <br /> Summary of Scope m <br /> 7, <br /> Initial tasks included the m <br /> w <br /> characterization of residuals flows "` ,44 1 m <br /> and loads from the various unit �. <br /> w <br /> �I <br /> processes;a comprehensive review b ; , ? , <br /> ti <br /> of plant operations with a focus on 4 .,i 4 A <br /> o <br /> process optimization to minimize X O <br /> waste streams;and assistance to K <br /> DWS to provide incentives to new z <br /> sludge hauling contracts to increase r 1 <br /> removal effectiveness.Site visits i z <br /> were conducted with DWS staff and c <br /> representatives of the supplier of <br /> m <br /> tai:':' <br /> kL cir<i r i 1w -0 <br /> .:,.. •:1. ¢ a.., <br /> es: riO <br /> 1. r ro z <br /> CAROLLO / QUALIFICATIONS / JUNE 2023 6 <br /> B:\Pursuits\CIlent831HON)\HawaliCounty\EnvMgmtDept\On-Call FY23-24\Oua10623\PL.4 CmntyPing_Cmnty\Indd\01_FirmOvervlew_PL4 <br />