Attachment A – PCSM BMP Descriptions
The BMP descriptions below are from Attachment A of the MS4 Annual Report User Guide, dated June 7, 2023. The BMP types are available as a type selection within CSDatum so that your data will align with DEP eReporting requirements.
Bioretention - Raingarden (A/B soils w/ underdrain)
An excavated pit backfilled with engineered media, topsoil, mulch, and vegetation. These are planting areas installed in shallow basins in which the storm water runoff is temporarily ponded and then treated by filtering through the bed components, and through biological and biochemical reactions within the soil matrix and around the root zones of the plants. This BMP has an underdrain and is in A or B soil.
Reporting Metric: Drainage Area, Units: Acres
Bioretention - Raingarden (A/B soils w/o underdrain)
An excavated pit backfilled with engineered media, topsoil, mulch, and vegetation. These are planting areas installed in shallow basins in which the storm water runoff is temporarily ponded and then treated by filtering through the bed components, and through biological and biochemical reactions within the soil matrix and around the root zones of the plants. This BMP has no underdrain and is in A or B soil.
Reporting Metric: Drainage Area, Units: Acres
Bioretention - Raingarden (C/D soils w/ underdrain)
An excavated pit backfilled with engineered media, topsoil, mulch, and vegetation. These are planting areas installed in shallow basins in which the storm water runoff is temporarily ponded and then treated by filtering through the bed components, and through biological and biochemical reactions within the soil matrix and around the root zones of the plants. This BMP has an underdrain and is in C or D soil. Use this BMP where the specific design is unknown.
Reporting Metric: Drainage Area, Units: Acres
Bioswale
With a bioswale, the load is reduced because, unlike other open channel designs, there is now infiltration into the soil. A bioswale is designed to function as a bioretention area.
Reporting Metric: Drainage Area, Units: Acres
Dry Detention Ponds
Dry Detention Ponds are depressions or basins created by excavation or berm construction that temporarily store runoff and release it slowly via surface flow or groundwater infiltration following storms.
Reporting Metric: Drainage Area, Units: Acres
Dry Extended Detention Ponds
Dry extended detention (ED) basins are depressions created by excavation or berm construction that temporarily store runoff and release it slowly via surface flow or groundwater infiltration following storms. Dry ED basins are designed to dry out between storm events, in contrast with wet ponds, which contain standing water permanently. As such, they are similar in construction and function to dry detention basins, except that the duration of detention of stormwater is designed to be longer, theoretically improving treatment effectiveness.
Reporting Metric: Drainage Area, Units: Acres
Filter Strip Runoff Reduction
Urban filter strips are stable areas with vegetated cover on flat or gently sloping land. Runoff entering the filter strip must be in the form of sheet-flow and must enter at a non-erosive rate for the site-specific soil conditions. A 0.4 design ratio of filter strip length to impervious flow length is recommended for runoff reduction urban filter strips.
Reporting Metric: Drainage Area, Units: Acres
Filter Strip Stormwater Treatment
Urban filter strips are stable areas with vegetated cover on flat or gently sloping land. Runoff entering the filter strip must be in the form of sheet-flow and must enter at a non-erosive rate for the site-specific soil conditions. A 0.2 design ratio of filter strip length to impervious flow length is recommended for stormwater treatment urban filter strips.
Reporting Metric: Drainage Area, Units: Acres
Filtering Practices
Practices that capture and temporarily store runoff and pass it through a filter bed of either sand or an organic media. There are various sand filter designs, such as above ground, below ground, perimeter, etc. An organic media filter uses another medium besides sand to enhance pollutant removal for many compounds due to the increased cation exchange capacity achieved by increasing the organic matter. These systems require annual inspection and maintenance to receive pollutant reduction credit.
Reporting Metric: Drainage Area, Units: Acres
Forest Buffer
Forest buffers are linear wooded areas that help filter nutrients, sediments and other pollutants from runoff as well as remove nutrients from groundwater. The recommended buffer width is 100 feet, with a 35 feet minimum width required.
Reporting Metric: Drainage Area, Units: Acres
Hydrodynamic Structures
Hydrodynamic Structures are devices designed to improve quality of stormwater using features such as swirl concentrators, grit chambers, oil barriers, baffles, micropools, and absorbent pads that are designed to remove sediments, nutrients, metals, organic chemicals, or oil and grease from urban runoff.
Reporting Metric: Drainage Area, Units: Acres
Impervious Surface Reduction
Disconnecting existing impervious area runoff from stormwater drainage systems such as directing rooftops and/or on-lot impervious surfaces to pervious areas with amended soils. Report disconnect to un-amended soils as Urban Filter Strip.
Reporting Metric: Drainage Area, Units: Acres
Infiltration Practices
A depression to form an infiltration basin where sediment is trapped and water infiltrates the soil. A sand layer and vegetation are required. No underdrains are associated with infiltration basins and trenches, because by definition these systems provide complete infiltration. Design specifications require infiltration basins and trenches to be built in A or B soil types. Use the other BMP without sand or vegetation where the specific design is unknown.
Reporting Metric: Drainage Area, Units: Acres
Other
If Other is selected as the BMP type, enter a brief description of the BMP.
Reporting Metric: Extent, Units: Varies
Permeable Pavement w/ Sand or Veg (A/B soils w/o underdrain)
Pavement or pavers that reduce runoff volume and treat water quality through both infiltration and filtration mechanisms. Water filters through open voids in the pavement surface to a washed gravel subsurface storage reservoir, where it is then slowly infiltrated into the underlying soils or exits via an underdrain. This BMP has no underdrain, has sand and/or vegetation and is in A or B soil.
Reporting Metric: Drainage Area, Units: Acres
Permeable Pavement w/ Sand or Veg (A/B Soils w/ underdrain)
Pavement or pavers that reduce runoff volume and treat water quality through both infiltration and filtration mechanisms. Water filters through open voids in the pavement surface to a washed gravel subsurface storage reservoir, where it is then slowly infiltrated into the underlying soils or exits via an underdrain. This BMP has an underdrain, has sand and/or vegetation and is in A or B soil.
Reporting Metric: Drainage Area, Units: Acres
Permeable Pavement w/ Sand or Veg (C/D soils w/ underdrain)
Pavement or pavers that reduce runoff volume and treat water quality through both infiltration and filtration mechanisms. Water filters through open voids in the pavement surface to a washed gravel subsurface storage reservoir, where it is then slowly infiltrated into the underlying soils or exits via an underdrain. This BMP has an underdrain, has sand and/or vegetation and is in C or D soil.
Reporting Metric: Drainage Area, Units: Acres
Permeable Pavement w/o Sand or Veg (A/B Soils w/o underdrain)
Pavement or pavers that reduce runoff volume and treat water quality through both infiltration and filtration mechanisms. Water filters through open voids in the pavement surface to a washed gravel subsurface storage reservoir, where it is then slowly infiltrated into the underlying soils or exits via an underdrain. This BMP has no underdrain, no sand or vegetation and is in A or B soil.
Reporting Metric: Drainage Area, Units: Acres
Permeable Pavement w/o Sand or Veg (A/B Soils w/ underdrain)
Pavement or pavers that reduce runoff volume and treat water quality through both infiltration and filtration mechanisms. Water filters through open voids in the pavement surface to a washed gravel subsurface storage reservoir, where it is then slowly infiltrated into the underlying soils or exits via an underdrain. This BMP has an underdrain, no sand or vegetation and is in A or B soil.
Reporting Metric: Drainage Area, Units: Acres
Permeable Pavement w/o Sand or Veg (C/D soils w/ underdrain)
Pavement or pavers that reduce runoff volume and treat water quality through both infiltration and filtration mechanisms. Water filters through open voids in the pavement surface to a washed gravel subsurface storage reservoir, where it is then slowly infiltrated into the underlying soils or exits via an underdrain. This BMP has an underdrain, no sand or vegetation and is in C or D soil. Use this BMP where the specific design is unknown.
Reporting Metric: Drainage Area, Units: Acres
Stream Restoration
Stream restoration is a change to the stream corridor that improves the stream ecosystem by restoring the natural hydrology and landscape of a stream and helps improve habitat and water quality conditions in degraded streams. Use this BMP if the specific project design is not known.
Reporting Metric: Extent, Units: Feet
Tree Planting
Urban tree planting is planting trees on urban pervious areas.
Reporting Metric: Extent, Units: Trees Planted
Vegetated Open Channels (A/B soils)
Open channels are practices that convey stormwater runoff and provide treatment as the water is conveyed. Runoff passes through either vegetation in the channel, subsoil matrix, and/or is infiltrated into the underlying soils. This BMP has no underdrain and is in A or B soil. Use this BMP where specific design is unknown.
Reporting Metric: Drainage Area, Units: Acres
Vegetated Open Channels (C/D soils)
Open channels are practices that convey stormwater runoff and provide treatment as the water is conveyed, includes bioswales. Runoff passes through either vegetation in the channel, subsoil matrix, and/or is infiltrated into the underlying soils. This BMP has no underdrain and is in C or D soil.
Reporting Metric: Drainage Area, Units: Acres
Wet Ponds and Wetlands
A water impoundment structure that intercepts stormwater runoff then releases it to an open water system at a specified flow rate. These structures retain a permanent pool and usually have retention times sufficient to allow settlement of some portion of the intercepted sediments and attached nutrients/toxics. There is little or no vegetation living within the pooled area. Outfalls are not directed through vegetated areas prior to open water release.
Reporting Metric: Drainage Area, Units: Acres