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Virginia Administrative Code
Title 9. Environment
Agency 25. State Water Control Board
Chapter 91. Facility and Aboveground Storage Tank (AST) Regulation
12/21/2024

9VAC25-91-190. GCS well monitoring.

A. All GCS wells required by 9VAC25-91-170 A 13 a in the ODCP requirements shall be monitored as follows:

1. Monthly gauging of GCS groundwater monitoring wells.

a. Measure and record static water levels monthly.

b. Reference all water-level measurements, including total well-depth measurements, from an established and documented point on the top of the well casing.

c. Measurements shall be correlated with mean sea level datum and measured to the nearest 0.01 foot.

2. Quarterly groundwater and vapor monitoring.

a. Quarterly vapor monitoring of all GCS wells identified in the ODCP-GCS shall be conducted prior to collecting quarterly groundwater samples.

b. Quarterly vapor monitoring consists of collecting one monitoring well headspace measurement.

c. Quarterly groundwater sampling (visual inspection) of all wells identified in the ODCP-GCS shall be conducted.

(1) Measure for free product on top of the groundwater.

(2) Collect groundwater samples for visual inspection.

d. Tabulate vapor measurements and quarterly visual groundwater monitoring results for each well sampled.

3. Annual groundwater monitoring for laboratory analysis.

a. Annual groundwater sampling of all wells identified in the ODCP groundwater characterization study (GCS) shall be conducted.

b. Annual groundwater monitoring consists of collecting groundwater samples for laboratory analysis.

c. Groundwater samples shall be collected and analyzed for BTEX and TPH for each well.

B. The GCS groundwater well monitoring should not be confused with the monitoring of groundwater wells utilized to satisfy 9VAC25-91-170 A 18 (i.e., leak detection wells).

Statutory Authority

§§ 62.1-44.2, 62.1-44.15, 62.1-44.34:15, 62.1-44.34:15.1 and 62.1-44.34:19.1 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 14, Issue 18, eff. June 24, 1998.

Website addresses provided in the Virginia Administrative Code to documents incorporated by reference are for the reader's convenience only, may not necessarily be active or current, and should not be relied upon. To ensure the information incorporated by reference is accurate, the reader is encouraged to use the source document described in the regulation.

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