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<br /> FIRM OVERVIEW ANO :8ACKGROUND
<br /> Mahinahina Water Treatment
<br /> Facility UV Disinfection Project
<br /> - COUNTY OF MAUI,DEPARTMENT OF WATER SUPPLY,HONOKOWAI,MAUI,HAWAII
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<br /> Client Reference:
<br /> Mr.Jason Koskey,O&M Supervisor-West District,
<br /> .r' County of Maui,Department of Water Supply
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<br /> 808.270.4303 /jason.koskey@co.maui.hi.us
<br /> The Mahinahina Water Treatment Facility(WTF)is a 2.5-mgd direct "; -' %` _,_,----:_-1,,,,..... -_-,,,;_,,,,,- I
<br /> filtration plant serving the Lahaina,Napili,Wahikuli,and Alaeloa r - ''
<br /> areas.The source of water for the facility is the Honolua Ditch,which
<br /> runs adjacent to the plant.In accordance with the Long Term 2M ""
<br /> Enhanced Surface Water Treatment Rule(LT2ESWTR),the County of • ? _:-
<br /> Maui,Department of Water Supply(DWS)conducted a second round :'^, h o
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<br /> of source water monitoring for Cryptosporidium, Giardia,E Coli,and �-_tr:-- -1 1° d
<br /> turbidity from October 2016 through September 2018.The highest ,,�
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<br /> arithmetic mean Cryptosporidium concentration in the Honolua ,. -- . ''
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<br /> Ditch was 0.078 oocysts/L in a consecutive 12-month period.As a -011"'"- -7---.101-, . �
<br /> result,and in accordance with LT2ESWTR,the source water was - A- 1-, ;46.—. ,k - -
<br /> classified in Bin 2,requiring the WTF to provide an additional 1.5-log - - vie FVVR z
<br /> Cryptosporidium removal by October 1,2021.DWS retained Carollo dI ' dd► c
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<br /> to prepare a basis of design report(BODR),complete the final design �`, I 5. - '4, .
<br /> of recommended facility modifications,and provide construction
<br /> management services to meet the new disinfection requirements by
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<br /> the established compliance deadline. �s -'' /
<br /> Key planning and design considerations °
<br /> Summary of Improvements m
<br /> addressed included: m
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<br /> WTF improvements primarily consisted of a new ultraviolet(UV) z
<br /> • UV disinfection upgrade of an operating treatment facility.
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<br /> disinfection process along with associated electrical,instrumentation, m
<br /> and mechanical piping modifications.Carollo evaluated a wide range • Close coordination with the State of Hawaii Department of Health. <
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<br /> of UV equipment as part of the BODR,with careful consideration • Resolution of complex hydraulics and piping configurations. m
<br /> given to those reactors that could be most easily installed within T
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<br /> • Fast-track design approach to meet schedule compliance. w
<br /> the existing filter gallery piping and fit within the current plant A
<br /> hydraulic profile.This resulted in the sole-source selection of a single CFD modeling for UV reactor revalida• tion. -I
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<br /> UV
<br /> UV manufacturer. • Coordination with a separate SCADA construction contract. 4,
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<br /> • Planning,design,and construction management services.
<br /> The new equipment was installed in the existing filter gallery on the C
<br /> effluent piping of each of the four filters.Due to the limited space Z
<br /> Design of the Mahinahina WTF modifications was"fast tracked"to <
<br /> available and the complicated existing piping in the filter basin meet the October 1,2021 compliance deadline. -0
<br /> gallery,special consideration was given to system piping layouts. z
<br /> Computational fluid dynamics(CFD)modeling was used to develop c
<br /> CFD-based dose models to quantify flow split and customize the inlet
<br /> piping layout in lieu of supplemental validation testing. a
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<br /> Detailed coordination with a separate SCADA contract was a key 0
<br /> element of construction phase services. D
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<br /> CAROLLO / QUALIFICATIONS /JUNE 2023
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<br /> B:\Pursuits\Client831HON)\HawaiiCounty\EnvMgmtDept\On-Call FY23-24\Qual0623\PL.4 CmntyPing_Cmnty\Indd\01_FirmOverview_PL4
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