Sewage Treatment Plant Multi-phased Project Begins
BNL's Sewage Treatment Plant (STP) was built in stages by the U.S. Army. Some sewer lines were installed as early as 1917. The old lines were repaired and upgraded by the Army in 1942. The STP was first upgraded by BNL in 1967.
BNL investigated the sewer lines and discovered they were leaking during a video camera survey conducted in 1987. In 1992, a multi-phased project was announced that called for upgrades to the sanitary sewer system over the next 10 years to improve treatment capability and prevent unmonitored discharges to the environment.
Under Phase I, the treatment plant was to be upgraded from a primary system to a tertiary system. In addition, 3,500 linear feet of the main trunk line to the plant is to be replaced. Phase II of the project calls for upgrading 14,000 feet of sewer lines, mainly in the core of the site. Under Phase III, another 18,000 linear feet of sewer lines will be replaced or lined and RHIC will be connected to the sanitary system. Phase II and III enhancements to the STP include untraviolet disinfection to replace chlorination and replacement of the anaerobic digester with an aerobic digester.
Upgrades began with replacement of the old sewer pipes leading to the STP in January 1993. The old lines were capped and left in place. In 1995, sludge was collected from 10 manholes along the retired and capped lines and analyzed for radionuclides. The sludge was removed. The old World War II-era Imhoff tanks used to process solid waste were removed, treated, and disposed of off site. The remaining concrete structure was demolished, backfilled with clean soil, and capped with concrete. In 1997, the plant was upgraded to tertiary treatment and effluent disinfection was changed from chlorine to ultraviolet light.
The 10-year plan was completed after BNL removed soils containing mercury and cesium-137 from the sand filter beds in 2002 and 2003. The former sludge drying beds, sand filter berms, and sewer lines were also remediated to remove low-levels of these contaminants.
In 2009, BNL began the process of renewing its New York State Pollutant Discharge Elimination System permit. New release standards to continue discharge to the Peconic River must be met for several metals. BNL is considering its options for meeting the more stringent standards.