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PIPA Recommended Practice ND11

ND11 "Reduce Transmission Pipeline Risk through Design and Location of New Parking Lots and Parking Structures"

Practice Statement Parking lots and parking structures should be preferentially located and designed to reduce the consequences that could result from a transmission pipeline incident and to reduce potential interference with transmission pipeline maintenance and inspections.

Audience(s): Local Government, Property Developer and Owner

Practice Description

Parking lots and parking structures can provide low occupant density, lower-risk land use adjacent to a pipeline right-of-way (ROW). Since human occupancy of parking lots or parking structures is likely to be short-term and low-density, they may be preferentially located to create a buffer between the transmission pipeline ROW and other occupied structures. In this manner, they may serve to reduce the exposure of other occupied structures during any potential pipeline incident. Enhanced fire protection and/or the use of materials and design providing enhanced fire endurance may be considered for parking structures adjacent to transmission pipelines to further mitigate the impact of a potential pipeline incident. Additionally, parking lots and parking structures may be designed to reduce potential interference with pipeline maintenance and inspections.

Parking structures cannot normally encroach onto a transmission pipeline ROW. Several factors should be considered in designing parking lots that encroach on a transmission pipeline ROW:

  • Written permission from the transmission pipeline operator will likely be required.
  • Parking areas very near or over the pipeline should be designed to limit loading that could damage the pipeline.
  • Parking lots covering portions of underground transmission pipeline ROW could hamper the discovery of pipeline leaks. To prevent this, parking lot design must take into account methods of improving leak detection. Examples could include periodic strips of grass or shrubbery, vent pipes, sensor strips, etc.
  • The effect of water runoff affecting the pipeline cathodic protection and soil cover should be considered when designing the parking lot. Runoff drains and gutters should not funnel water directly into the transmission pipeline ROW, as excess water could erode pipeline soil cover and subsurface pipeline support and could impact pipeline corrosion protection systems.
  • Medians and islands adjacent to the transmission pipeline ROW should not contain trees that would obscure the ROW or that have a root system that could damage the pipeline. Shrubs and other low landscaping plants are generally acceptable (see PIPA Recommended Practice ND-15).
  • Parking lots between a transmission pipeline and buildings should have an "air gap" between the parking lot and the buildings to reduce the potential for gas leaks to migrate underneath the parking lot and into the buildings.

The property developer should keep in mind that the parking lot might be disturbed by pipeline maintenance activities, including excavation. The transmission pipeline operator may also need to place pipeline markers, sniff points, and cathodic test stations, along the pipeline ROW, possibly within the parking lot itself. These can often be placed within medians and other landscaped areas.