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FIRM OVERVIEW AND BACKGROUND <br /> Mahinahina Water Treatment Facility <br /> Disinfection Improvements <br /> a � ' -� COUNTY OF MAUI, DEPARTMENT OF WATER SUPPLY,HONOKOWAI,MAUI,HAWAII <br /> Reference: <br /> Mr.Jason Koskey,O&M Supervisor—West District <br /> County of Maui,Department of Water Supply <br /> 808.270.4303 /jason.koskey@co.maui.hi.us <br /> The Mahinahina Water Treatment Facility(WTF)is a 2.5 million gallons <br /> per day(mgd)direct filtration plant serving the Lahaina,Napili, Project Highlights <br /> Wahikuli,and Alaeloa areas.The source of water for the facility is the • UV disinfection system retrofit within existing <br /> Honolua Ditch,which runs adjacent to the plant.In accordance with filter gallery. <br /> the Long Term 2 Enhanced Surface Water Treatment Rule(LT2ESWTR), <br /> • <br /> the County of Maui Department of Water Supply conducted a second Close coordination with the Hawaii <br /> round of source water monitoring for Cryptosporidium,Giardia,E Department of Health. <br /> Coll,and turbidity from October 2016 through September 2018.The • Resolution of complex hydraulics and <br /> highest arithmetic mean Cryptosporidium concentration in the Honolua piping configurations. <br /> Ditch was 0.078 oocysts/L in a 12-month period.As a result,and in <br /> accordance with LT2ESWTR,the source water was classified in Bin • Fast-track design approach to meet the <br /> 2,requiring the WTF to provide an additional 1.5-log Cryptosporidium compliance schedule. <br /> removal by October 1,2021.Carollo prepared a basis of design • CFD modeling for UV reactor revalidation. <br /> report(BODR),completed the final design of recommended facility <br /> modifications,and provided construction management services • Coordination with a concurrent <br /> to meet the new disinfection requirements by the established SCADA project. <br /> compliance deadline. • Planning,design,and construction 0 <br /> management services. Z o <br /> Summary of Scope < c <br /> WTF improvements primarily consisted of a new ultraviolet(UV) i; O <br /> Carollo's design team worked Zm <br /> disinfection process along with associated electrical,instrumentation, z a <br /> and mechanical piping modifications.Carollo evaluated a wide range closely with operations staff to * <br /> of UV equipment as part of the BODR,with careful consideration given install the new UV system within the K -0 <br /> to those reactors that could be most easily installed within the existing existing filtration gallery, minimizing zz <br /> filter gallery piping and fit within the current plant hydraulic profile. ; c <br /> construction costs. <br /> This resulted in the sole-source selection of a single UV manufacturer. m o <br /> o � <br /> D <br /> The new equipment was installed in the existing filter gallery on the r' <br /> m <br /> effluent piping of each of the four filters.Due to the limited space ', 'VI�P��� �' z <br /> available and the complicated existing piping in the filter basin t' f� o <br /> Lgallery,special consideration was given to system piping layouts. Z m <br /> Computational fluid dynamics(CFD)modeling was used to develop I - D w <br /> CFD-based dose models to quantify flow split and customize the " •_ `sq, - ~ , -0 o <br /> inlet piping layout in lieu of supplemental validation testing.Detailed ' �' ? m <br /> it tl, o <br /> coordination with a separate SCADA contract was a key element of 1 I I r , �' :� u r <br /> .�� D m <br /> construction phase services. ... M , ." m T <br /> Dn <br /> —I I <br /> O <br /> Z Am <br /> CAROLLO / QUALIFICATIONS /JUNE 2024 16 <br /> \\io-bd-1\BD-DATA\Marketing\Pursuits\Client831HONl\HawaiiCounty\EnvMgmtDept\On-Call FY24-25\Qua10624\PL.4-CommunityPlanning_Community\Indd\O1_FirmOverview_PL4 <br />