Erosion and Sediment Pollution Control Program Manual.pdf

A utility line crossing of a stream channel 10 feet in bottom width or less should be completed within
24 hours from start to finish, including the trench backfilling, stabilization of stream banks and
stabilization of the area 50 feet back from the top of each stream bank. Stream channels between 10
and 100 feet in width should be completed within 48 hours or as approved in writing from the
Department.
Facilities for removing sediment from pumped water should be available at the stream-crossing site
before trenching commences and maintained until trench backfilling is completed. Assembly areas,
temporary equipment and non-hazardous material storage areas should be located at least 50 feet
back from the top of stream bank.
Preserving groundwater hydrology
Projects with utility lines, including stormwater, often involve piping alignments along a stream corridor
to avoid or minimize direct impacts to a stream, wetland or riparian zone. Maintaining the natural
mechanisms for groundwater movement in these areas is often very important for sustaining baseflow
to receiving streams and for preserving riparian vegetation. In order to avoid creating a preferential
pathway for groundwater flow (i.e. “French Drain” effect within the utility trench backfill - usually
permeable aggregate), the use of trench plugs at a maximum spacing of 1,000 feet is warranted.
Properly installed trench plugs will block the flow of groundwater along the path of the utility pipe/trench
and maintain the natural groundwater path.
363-2134-008 / March 31, 2012 / Page 286