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D.C. Municipal Regulations (Last Updated: September 13, 2017) |
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Title 20. ENVIRONMENT |
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Chapter 20-60. UNDERGROUND STORAGE TANKS - RELEASE DETECTION |
Section 20-6010. GROUNDWATER MONITORING
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6010.1Testing or monitoring for regulated substances on the ground water or in the tank excavation zone shall meet the requirements of this section.
6010.2The regulated substance stored shall be immiscible in water and have a specific gravity of less than one (1).
6010.3If testing or monitoring for regulated substances on ground water, the ground water shall never be more than twenty feet (20') from the ground surface and the hydraulic conductivity of the soil(s) between the UST system and the monitoring wells or devices shall not be less than one one-hundredth of a centimeter per second (0.01 cm/sec). The soil should consist of gravel, coarse to medium sand, coarse silt, or other permeable materials.
6010.4The slotted portion of the monitoring well casing shall be designed to prevent migration of natural soils or filter pack into the well and to allow entry of regulated substance on the water table into the well under both high and low ground water conditions.
6010.5Monitoring wells shall be sealed from the ground surface to the top of the filter pack.
6010.6Monitoring wells or devices shall intercept the excavation zone or shall be as close to the excavation zone as is technically feasible.
6010.7Before using ground-water monitoring, the owner or operator shall assess the excavation zone to ensure compliance with §§ 6010.2 through 6010.6, and to establish the number and position of monitoring wells or devices that will detect releases within the excavation zone from any portion of the tank that routinely contains product. A minimum of two (2) wells shall be required in each excavation zone.
6010.8The continuous monitoring devices or manual methods used shall be capable of detecting the presence of at least one-eighth inch (1/8") of free regulated substance on top of the ground water in a monitoring well.
6010.9Each monitoring well shall be clearly marked and secured to avoid unauthorized access and tampering.