Bottomless Sand Filter
Description of Technology
Descriptions for proprietary technologies are from the Massachusetts DEP Approval Letters for the technology.
The BSF is an alternative component of a soil absorption system (SAS) for residential onsite sewage disposal systems where soil or site conditions make conventional soil absorption systems more costly to construct or infeasible. A conventional SAS may be more costly to construct or infeasible where there is a shallow water table and/or limited area for the siting of a conventional system. As compared to a conventional system, in certain instances, the BSF provides for higher loading rates and requires significantly less filling of land, less land area, and less disturbance of the site.
The System consists of a BSF preceded by a treatment unit. The treatment unit prior to the BSF must be a unit that is capable of providing secondary treatment and must already be approved by the Department. A specific volume or dose of the treatment unit effluent is periodically pumped at set time intervals to the BSF. The effluent from the treatment unit is pumped onto and evenly distributed over the surface of the BSF. The BSF consists of at least 2 feet of sand media meeting stringent specifications through which the wastewater percolates and is filtered. The bottom of the BSF rests on existing permeable soils or rests on approved fill above existing permeable soils into which the final effluent is discharged for disposal.
Massachusetts Technology Approvals
|Nitrogen Removal Credit|
|Phosphorus Removal Credit|
Please check the Title 5 Innovative/Alternative Technology Approval Letters webpage at Massachusetts DEP for the most up-to-date information.