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Virginia Administrative Code
Title 4. Conservation And Natural Resources
Agency 25. Department of Energy
Chapter 170. Geothermal Energy Regulations
9/24/2022

4VAC25-170-70. Groundwater monitoring.

A. 1. Groundwater shall be monitored through special monitoring wells or existing water wells in the area of impact, as determined by the department.

2. Monitoring shall be performed and reported to the division director daily on both water quality and piezometric head for the first 30 days of geothermal production. Thereafter, quarterly tests for piezometric head and for water quality shall be reported to the division director.

3. The monitoring of groundwater shall meet the following conditions:

a. A minimum of one monitoring well per production or injection well is required. Monitoring wells shall monitor those significant potable aquifers through which the well passes as required by the department.

b. The monitoring wells shall be located within the first 50% of the projected cone of depression for the geothermal production well.

c. The wells shall be constructed to measure variations in piezometric head and water quality. Groundwater shall be chemically analyzed for the following parameters: mineral content (alkalinity, chloride, dissolved solids, fluoride, calcium, sodium, potassium, carbonate, bicarbonate, sulfate, nitrate, boron, and silica); metal content (cadmium, arsenic, mercury, copper, iron, nickel, magnesium, manganese, and zinc); and general parameters (pH, conductivity, dissolved solids, and hardness).

d. The department may require additional analyses if levels of the parameters in subdivision 3 c of this subsection indicate their necessity to protect groundwater supplies.

B. 1. Chemical analyses of geothermal fluids shall be filed with the division director on an annual basis.

2. Samples for the chemical fluid analysis shall be taken from fluid as measured at the discharge point of the production well at the conclusion of a two-hour production test.

3. The production fluid shall be chemically analyzed for the following parameters: mineral content (alkalinity, chloride, dissolved solids, fluoride, calcium, sodium, potassium, carbonate, bicarbonate, sulfate, nitrate, boron, and silica); metal content (cadmium, arsenic, mercury, copper, iron, nickel, magnesium, manganese, and zinc); gas analyses (hydrogen sulfide, ammonia, carbon dioxide, and gross alpha); and general parameters (pH, conductivity, and dissolved solids).

4. The department may require additional analyses if levels of the parameters in subdivision 3 of this subsection indicate follow-up tests are necessary.

C. 1. Subsidence shall be monitored by the annual surveys of a professional engineer or certified surveyor from vertical benchmarks located above the projected cone of depression, as well as points outside its boundaries. The surveys shall be filed with the division director by the operator or designated agent.

2. The department may order micro-earthquake monitoring, if surveys indicate the occurrence of subsidence.

D. 1. The operator, owner, or designated agent shall maintain records of any monitoring activity required in his permit or by this chapter. All records of monitoring samples shall include:

a. The well identification number.

b. The date the sample was collected.

c. Time of sampling.

d. Exact place of sampling.

e. Person or firm performing analysis.

f. Date analysis of the sample was performed.

g. The analytical method or methods used.

h. Flow-point at which sample was taken.

i. The results of such analysis.

2. The operator, owner, or designated agent shall retain for a period of five years any records of monitoring activities and results, including all original strip chart recordings of continuous monitoring installations. The period of retention will automatically be extended during the course of any litigation regarding the discharge of contaminants by the permittee until such time as the litigation has ceased or when requested by the division director. This requirement shall apply during the five-year period following abandonment of a well.

Statutory Authority

§ 45.1-179.7 of the Code of Virginia.

Historical Notes

Derived from VR480-04-13 § 7, eff. May 1, 1984; amended, Virginia Register Volume 29, Issue 2, eff. October 24, 2012; Volume 33, Issue 21, eff. July 27, 2017.

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