Carmel Highlands Onsite Wastewater Management Study

Monterey County

Client:  Monterey County Health Department

In light of the recent trend toward the installation of individual onsite domestic water wells, the Regional Water Quality Control Board (RWQCB) alerted the County of Monterey to an immediate potential threat to public health, safety, and welfare posed by permitting additional onsite wastewater treatment systems (OWTS) on individual lots in the Carmel Highlands coastal area, 3 miles south of Carmel along Highway 1.  The RWQCB subsequently directed the County to conduct an investigation of the Carmel Highlands area, which includes approximately 450 developed residential parcels, some commercial uses, and 105 undeveloped parcels, in order to prepare a sufficiently detailed wastewater management plan that addresses the capacity for additional OWTS and provides appropriate measures for long-term wastewater management in the area.

The County authorized Questa to conduct an onsite wastewater investigation and management study of the area.  The study, by Questa and its sub-consultants, Todd Engineers and Denise Duffy & Associates, included an evaluation of soil and hydrogeologic conditions, local onsite wastewater treatment and disposal practices, development potential, existing and potential water quality impacts, measures to improve OWTS practices, sewerage alternatives, and recommendations for long-term wastewater management in the Carmel Highlands.  Based on the study, Questa then developed an Onsite Wastewater Management Plan (OWMP) to provide oversight and guidance on the use of appropriate methods of wastewater treatment and disposal, and assisted in the development of an OWTS building and repair ordinance for the Carmel Highlands area. Questa also assisted the County with the development of ordinance language and an Administrative Manual for consolidation of technical and program requirements.