Construction Proximate to Existing Utility Lines
The following requirements apply whenever Technical Services reviews member requests for permits to build additions, decks, and other permanent structures. Permanent structures are those that are supported by and anchored to structural foundations embedded into the earth.
- Underground Utility Lines in General
- Storm Water Drainage Mains and Laterals; Sanitary Sewer Laterals Only
- Sanitary Sewer Mains and All Water Supply Piping (components of the system owned by WSSC)
No construction directly over known or suspected underground sewers is permitted without notifying GHI. GHI will determine the location of underground utility line(s) affected utilizing the 1936 Town of Greenbelt Record Plans of Utilities for the purpose. If the lines are not shown of these plans, GHI will estimate their location based upon available data.
If the existence of a line is still suspected, GHI will recommend that member retain a firm that specializes in the detection and location of underground utilities.
All taps, repairs, and changes to underground utilities must be in conformance with GHI's Specifications Section 02725.
Rigid plastic and hubless drainage piping, including offsets and jumps, shall rest on a continuous bed of sand, gravel or crushed stone, a minimum of four (4) inches deep below the pipe; maximum aggregate size shall be three-quarter (¾) inches (MD #6 and smaller). Bedding material shall be placed on both sides of the pipe equal in depth to the pipe diameter.
Utility lines may be diverted around addition, at the member's expense, in order to meet the minimum clearances listed below. The following conditions apply:
All utility lines must employ no greater than 45° bends to accomplish the bypass;
A cleanouts must be installed in advance of all 90° bends around the addition, as directed by Technical Services at the time it furnishes the member with preliminary schematics of the new by-pass line. Cleanouts are to constructed and capped in compliance with GHI specifications.
Written permission from neighbors whose yards are affected by the change must accompany the request.
All depths: 3' from outermost face of exterior wall's foundation at all points.
New lines must not be buried below the 45 degree angle of repose representing the side walls of an open-trench excavation. The concept is to allow future excavation down to the line without undermining the addition's foundation.
New lines must be located, both vertically and horizontally, so as to ensure positive drainage in the direction of the system's outfall.
If a sanitary sewer or any underground water line that has been identified as the responsibility of WSSC is in question, written permission from WSSC must be obtained by the member requesting. GHI can provide the appropriate layout drawing and contact information.
WSSC will most likely require that the member retain a professional civil engineer to prepare constructions drawings of the modification to their systems.
In no instance may clearances be less than those listed above.
