PD Background Report Kamehameha Schools (PL-SPP-2023-037)

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5. INFRASTRUCTURE 5.1 Existing and Proposed Wastewater Disposal Existing Conditions There are currently no County wastewater services in the project area. On Parcel 38, domestic wastewater is disposed of on-site in an Individual Wastewater System (IWS) consisting of a 1,200-gallon precast concrete septic tank and 7-foot diameter seepage pit located in the driveway between Building A and Building B. On Parcel 14, domestic wastewater is disposed of on-site in an existing cesspool. This cesspool will be closed and properly backfilled with the removal of the existing residence. Proposed Due to the increase in projected sewer demands generated by the Hi`ialo/Captain Cook Learning Center program, an additional IWS will be constructed to supplement the existing one. The IWS will include a 2,000- to 2,500-gallon septic tank. The process will include IWS compliance review and Department of Health (DOH) coordination during the design phase,with IWS permit obtained during design and construction of the project. 5.2 Existing and Proposed Water Facilities Existing Conditions Potable water service to the Project Area is provided by the County Department of Water Supply (DWS). DWS indicated via telephone conversation that an existing 8-inch diameter water main in Mamalahoa Highway provides water service to the Project Area. Three existing 5/8-inch water meters are located in the Mamalahoa Highway right-of-way and service Parcel 14, Parcel 38, and Parcel 40. DWS indicated via e-mail that the pressure in the water system is approximately 120 pounds per square inches (psi). Based on visual observations, there does not appear to be fire protection service to the site, and no fire hydrants were observed. Proposed Based on projected water demands and fixture units needed for the Project Area, a new 1-inch domestic meter will replace the existing 5/8-inch water meter. A new reduced pressure principal backflow preventer (RPBP) will be installed for the 1-inch meter as required by the DWS Water System Standards. Per the DWS Water System Standards, the average daily demand for the project is anticipated to be approximately 4,000 gallons. Maximum daily demand is anticipated to be about 6,000 gallons per day. No new fire sprinklers will be installed as part of this project. Fire protection requirements will be determined during the design phase of the project, however, it is 8