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FIRM OVERVIEW AND BACKGROUND <br /> Mahinahina Water Treatment Facility <br /> Disinfection Improvements <br /> €. , . <br /> ° 1 COUNTY OF MAUI,DEPARTMENT OF WATER SUPPLY,HONOKOWAI,MAUI,HAWAII <br /> Client 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 /> Coil,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 <br /> management services. o <br /> Summary of Scope <br /> 7, Z <br /> WTF improvements primarily consisted of a new ultraviolet(UV) p, o <br /> Carollo's design team worked <br /> disinfection process along with associated electrical,instrumentation, N <br /> and mechanical piping modifications.Carollo evaluated a wide range closely with operations staff to A a <br /> N - <br /> of UV equipment as part of the BODR,with careful consideration given install the new UV system within the i o <br /> to those reactors that could be most easily installed within the existing existing filtration gallery, minimizing w -o <br /> filter gallery piping and fit within the current plant hydraulic profile. o K <br /> construction costs. K m <br /> This resulted in the sole-source selection of a single UV manufacturer. K z <br /> zo <br /> The new equipment was installed in the existing filter gallery on the 3 - r'` °Tu A It -< <br /> effluent piping of each of the four filters.Due to the limited space ' N T > o <br /> available and the complicated existing piping in the filter basin 411.111.11 -::a.- z z <br /> z K <br /> gallery,special consideration was given to system piping layouts. 7,7; 5-Z <br /> Computational fluid dynamics(CFD)modeling was used to develop I' -�� K K <br /> CFD-based dose models to quantifyflow split and customize the _ '".q. z <br /> inlet piping layout in lieu of supplemental validation testing.Detailed - .'S4: i( ., -< m <br /> coordination with a separate SCADA contract was a key element of "'1 1 I I '- 4 v z z <br /> , <br /> construction phase services. "`' Z <br /> M t z <br /> ( > <br /> x <br /> D <br /> z <br /> zz <br /> D <br /> r <br /> CAROLLO/ QUALIFICATIONS /JUNE 2024 16 <br /> \\io-bd-1\BD-DATA\Marketing\Pursuits\Client831HONl\HawaiiCounty\EnvMgmtDept\On-Call FY24-25\Qua10624\PL.3-CommunityPlanning_CommPlanAssist\Indd\O1_FirmOverview_PL3 <br />