3. Dry Well / Seepage Pit

A dry well or seepage pit is a subsurface storage facility that temporarily stores stormwater
runoff from roofs and infiltrates it into the surrounding soils. Roof downspouts connect directly
to a dry well or seepage pit that is an excavated pit filled with clean angular stone with an
overflow pipe to ensure the system will not be overwhelmed. Prefabricated chamber systems or
perforated pipe sections are commercially available for use as dry wells and should be designed,
constructed and maintained according to the manufacturer's recommendations. For more
information on dry wells and seepage pits refer to the PA DEP BMP Manual 6.4.6.

Design considerations:

• A dry well / seepage pit should be located on nearly level to gently sloping ground and no
  closer than 10 feet to a building foundation and 25 feet from septic field or wellhead.
• A dry well / seepage pit can vary in length, width and depth, but should be a minimum
  depth of 3 feet.
• A downspout should direct water to the surface, a system of perforated pipes should
  distribute the water throughout the system with an inspection/cleanout pipe to the surface,
  and an over flow pipe should outlet excess water during intense storms.
• The storage system can be clean angular stone, separated from soil layers by four (4)
  inches of straw (top and bottom) or a nonwoven geotextile (top, sides, and bottom).
• The outlet from the dry well / seepage pit should be safely conveyed to a stable vegetated
  area, natural watercourse, the curb or gutter line of roadway or existing storm
  collection/conveyance/control system as applicable.

Maintenance:

• Drywells and seepage pits should be inspected at least 4 times a year, and after each
  storm event exceeding 1 inch.
• Remove sediment, debris, detritus and any other waste material from the system as
  necessary.
• Regularly clean out gutters and downspouts to ensure proper connections and to maintain
  effectiveness of the system.
• Replace any filter screen or clean out any sump box that may intercept roof runoff as
  necessary.

• 3. Dry Well / Seepage Pit

  A dry well or seepage pit is a subsurface storage facility that temporarily stores stormwater
  runoff from roofs and infiltrates it into the surrounding soils. Roof downspouts connect directly
  to a dry well or seepage pit that is an excavated pit filled with clean angular stone with an
  overflow pipe to ensure the system will not be overwhelmed. Prefabricated chamber systems or
  perforated pipe sections are commercially available for use as dry wells and should be designed,
  constructed and maintained according to the manufacturer's recommendations. For more
  information on dry wells and seepage pits refer to the PA DEP BMP Manual 6.4.6.

  Design considerations:

  
  

• 4. Alternative BMP Capture and Re-Use (rain barrel/cistern)
  

  Rain barrels and cisterns are above or below ground containers used for temporary
  storage of rainwater, to be used for landscape irrigation and other similar uses after the
  rain has ended. A rain barrel or cistern cannot be used as a volume control because
  infiltration is not guaranteed after a storm event, but they are viable alternative method to
  capture and reuse stormwater.
  

  Considerations:
  

• Rain barrels and cisterns should be directly connected to a downspout with a  mosquito screen

• There should be a means to release the water after a storm event to provide storm
  volume for the next event

• 
  

• An overflow, near the top of the container should direct water to a vegetated area
  away from any structures

• 
  

• Barrels can be connected in series to provide more volume collection
•