ND16 “Locate and Design Water Supply and Sanitary Systems to Prevent Contamination and Excavation Damage”
Practice Statement Individual water supplies (water wells), small public/private water systems and sanitary disposal systems (septic tanks, leach or drain fields) should be designed and located to prevent excavation damage to transmission pipelines, interference with transmission pipeline maintenance and inspections, and environmental contamination in the event of a transmission pipeline incident.
Audience(s): Local Government, Property Developer and Owner
Practice Description
Proper location and design of water/sanitary systems located adjacent to a transmission pipeline are vital to both public safety and the integrity of the pipeline. The design and location of these systems should take into consideration the potential impact on the water/sanitary system and on the transmission pipeline, resulting from activities associated with the installation, operation, and maintenance of the pipeline or the water/sanitary system. Considerations should include the potential for excavation damage to the water/sanitary system or the transmission pipeline, and the potential for contamination of the water/sanitary system from a pipeline incident.
If a water well is to be installed near a transmission pipeline, the pipeline and pipeline appurtenances (e.g., cathodic protection system) should be clearly located and identified Water supply drill rigs should stay clear of the pipeline right-of-way (ROW) to ensure no direct damage to the pipeline or pipeline appurtenances from drilling or movement of the drill rig.
To reduce the risk of contaminating a water well during a hazardous liquid transmission pipeline incident, it is generally best to place the well up-gradient from the pipeline. (Keep in mind that groundwater hydraulic gradients don’t necessarily follow surface topography.) The risk of contamination during a pipeline incident for wells that cannot be placed up-gradient of a hazardous liquid pipeline can be reduced by increasing the down-gradient distance from the pipeline and by ensuring that wellheads are properly sealed. Note that gas transmission pipelines do not typically pose a threat for water contamination, unless liquids are present in the gas stream.
When installing individual sanitary disposal systems (septic systems and leach or drain fields) near transmission pipelines, the septic tank and drain field should be located off the pipeline ROW but not placed in an area immediately adjacent to the ROW where heavy equipment used in pipeline maintenance might damage the septic tank or drain field.
References
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