Specifications include, but are not limited to: Rehabilitation of SDS001 involves reviewing previously collected geotechnical, survey, drainage, and storm drain condition assessment data to determine the corrective measures necessary to repair and/or replace the majority of the system. A storm drain condition assessment was completed in 2020 for the POA’s major storm drain systems. The assessment findings for SDS001 are provided in ATTACHMENT D. Findings include a list of the deficiencies observed, and a link to available system photos and videos. In 1997, CH2MHill and HDR published a drainage study for the POA’s major storm drain systems including SDS001 which they refer to as the Tote System. This study is included in ATTACHMENT E. Since SDS001 was originally constructed in 1986, the POA lease properties have continued to develop requiring additional drainage facilities. Over the last 36 years the POA has installed over 6,000 feet of pipe and numerous structures to support this development. The piping is made up of metal and/or plastic of various types and sizes, including subdrain. The structures are comprised of field inlets, catch basins and manholes. See ATTACHMENT C for detailed maps of the existing infrastructure. Over the years tidal surcharge has deposited heavy amounts of silt within this system making regular maintenance difficult. A separate POA storm drain project will repair and/or replace the outfall piping and structures for four storm drain systems damaged in the November 2018 earthquake, including SDS001. The project will rehabilitate and/or install new storm drain structures and piping from Cook Inlet upstream to Tidewater Road and provide an inline check valve in every outfall to eliminate silts from entering the system. This project is currently in design and construction is expected to occur in Summer 2023.
