Code of Colorado Regulations
400 - Department of Natural Resources
404 - Oil and Gas Conservation Commission
2 CCR 404-1 - PRACTICE AND PROCEDURE
Section 615 - GROUNDWATER BASELINE SAMPLING AND MONITORING

Universal Citation: 2 CO Code Regs 404-1 ยง 615

Current through Register Vol. 47, No. 17, September 10, 2024

a. Applicability and Effective Date.

(1) This Rule applies to oil Wells, gas Wells ("Oil and Gas Wells"), Multi-Well Sites, and Class II UIC Wells for which a Form 2, or Form 4, Notice to Recomplete, is submitted or pending on or after January 15, 2021. Oil and Gas Wells, Multi-Well Sites, and Class II UIC Wells operating under a Form 2 approved prior to January 15, 2021, will continue to follow the sampling protocols required by their permits at the time that the Form 2 was approved.

(2) Nothing in this Rule 615 is intended, and will not be construed, to preclude or limit the Director from requiring Groundwater sampling or monitoring at other Production Facilities consistent with other applicable Commission Rules, including but not limited to the oil and gas location assessment process, and other processes in place pursuant to the Commission's 900 Series Rules (Form 15, Earthen Pit Report/Permit, Form 27, Site Investigation and Remediation Workplan, and Form 28, Centralized E&P Waste Management Facility Permit).

(3) An Operator may elect, or the Director may require an Operator to install one or more Groundwater monitoring wells to satisfy, in full or in part, the requirements of Rule 615.b, but installation of monitoring wells is not required under this Rule 615.

b. Sampling Locations. Initial baseline samples and subsequent monitoring samples will be collected from all Available Water Sources, up to a maximum of 4, within a 1/2 mile radius of a proposed Oil and Gas Well, Multi-Well Site, or Class II UIC Well. If more than 4 Available Water Sources are present within a 1/2 mile radius of a proposed Oil and Gas Well, Multi-Well Site, or Class II UIC Well, the Operator will select the 4 sampling locations based on the following criteria:

(1) Proximity. Available Water Sources closest to the proposed Oil and Gas Well, Multi-Well Site, or Class II UIC Well are required.

(2) Type of Water Source. Well-maintained domestic water wells are required over other Available Water Sources.

(3) Orientation of Sampling Locations.To the extent Groundwater flow direction is known or reasonably can be inferred, sample locations from both down-gradient and up-gradient are preferred over cross-gradient locations. Where Groundwater flow direction is uncertain, sample locations should be chosen in a radial pattern from a proposed Oil and Gas Well, Multi-Well Site, or Class II UIC Well.

(4) Multiple Identified Aquifers Available. Where multiple defined Aquifers are present, sampling the deepest and shallowest identified Aquifers is required.

(5) Condition of Water Source. An Operator is not required to sample Water Sources that are determined to be improperly maintained, nonoperational, or have other physical impediments to sampling that would not allow for a representative sample to be safely collected or would require specialized sampling equipment (e.g., Shut-In Wells, wells with confined space issues, wells with no tap or pump, non-functioning wells, intermittent springs).

c. Inability to Locate an Available Water Source. Prior to spudding, an Operator may request an exception from the requirements of this Rule 615 by filing a Form 4 for the Director's review and approval if:

(1) No Available Water Sources are located within 1/2 mile of a proposed Oil and Gas Well, Multi-Well Site, or Class II UIC Well;

(2) The only Available Water Sources are determined to be unsuitable pursuant to Rule 615.b.(5). An Operator seeking an exception on this ground will document the condition of the Available Water Sources it has deemed unsuitable; or

(3) The owners of all Water Sources suitable for testing under this Rule refuse to grant access despite an Operator's reasonable, good faith efforts to obtain consent to conduct sampling. An Operator seeking an exception pursuant to this Rule 615.c.(3) will document the efforts used to obtain access from the owners of suitable Water Sources.

(4) If the Director takes no action on the Form 4 within 10 business days of receipt, the requested exception from the requirements of this Rule 615.c will be deemed approved.

d. Timing of Sampling.

(1) Initial sampling will be conducted within 12 months prior to setting conductor pipe in a Well or if no conductor is present prior to spudding the first Well on a Multi-Well Site, or commencement of drilling a Class II UIC Well.

(2) Subsequent Monitoring. One subsequent sampling event will be conducted at the initial sample locations between 6 and 12 months, and a second subsequent sampling event will be conducted between 60 and 72 months following completion of the Well or Class II UIC Well, or the last Well on a Multi-Well Site. Additional subsequent samples will be collected every 5 years (57 to 63 month interval) for the life of the Well. A post abandonment sample will be collected 6 to 12 months after the Oil and Gas Well has been Plugged and Abandoned. Wells that are drilled and abandoned without ever producing hydrocarbons are exempt from subsequent monitoring sampling under this Rule 615.d.(2).

(3) Previously Sampled Water Sources. In lieu of conducting the initial sampling required pursuant to Rule 615.d.(1), or the second subsequent sampling event required pursuant to Rule 615.d.(2), an Operator may rely on water sampling analytical results obtained from an Available Water Source within the sampling area provided:
A. The previous water sample was obtained within the 18 months preceding the initial sampling event required pursuant to Rule 615.d.(1), or any subsequent sampling event required pursuant to Rule 615.d.(2);

B. The sampling procedures, including the constituents sampled for, and the analytical procedures used for the previous water sample were substantially similar to those required pursuant to Rules 615.e.(1) & (2), below; and

C. The Director timely received the analytical data from the previous sampling event.

(4) The Director may require additional sampling at any time as a result of information indicating a potential change in or impact to groundwater.

e. Sampling Procedures and Analysis.

(1) Sampling and analysis will be conducted in conformance with an accepted industry standard pursuant to Rule 913.b.(2). A model Sampling and Analysis Plan ("COGCC Model SAP") will be posted on the Commission's website, and will be updated periodically to remain current with evolving industry standards. Sampling and analysis conducted in conformance with the COGCC Model SAP will be deemed to satisfy the requirements of this Rule 615.e.(1). Upon request, an Operator will provide its sampling protocol to the Director.

(2) The analyses for samples collected as required by Rule 615 will include:
A. pH;

B. Specific conductance;

C. Total dissolved solids ("TDS");

D. Dissolved gases (methane, ethane, and propane);

E. Alkalinity (total, bicarbonate, and carbonate as CaCO3);

F. Major anions (bromide, chloride, fluoride, sulfate, nitrate and nitrite as N, and phosphorus);

G. Major cations (calcium, iron, magnesium, manganese, potassium, and sodium);

H. Other elements (barium, boron, selenium, and strontium);

I. Presence of bacteria (iron related, sulfate reducing, and slime forming);

J. Total petroleum hydrocarbons ("TPH") as total volatile hydrocarbons (C6 to C10) and total extractable hydrocarbons (C10 to C36); and

K. BTEX compounds (benzene, toluene, ethylbenzene, and xylenes ("BTEX")).

(3) Field observations such as odor, water color, sediment, bubbles, and effervescence as well as the presence or absence of H2S gas will be documented. The location of the sampled Water Sources will be surveyed pursuant to Rule 216.

(4) Dissolved Gas Detections. If a free or dissolved gas (methane, ethane, or propane) concentration greater than 1.0 milligram per liter ("mg/l") is detected in a water sample, gas compositional analysis and stable isotope analysis of the gas will be performed to determine gas type.
A. The compositional analysis should include:
i. hydrogen;

ii. argon;

iii. oxygen;

iv. carbon dioxide;

v. nitrogen;

vi. methane (C1);

vii. ethane (C2);

viii. ethene (C2H4);

ix. propane (nC3);

x. isobutane (iC4);

xi. butane (nC4);

xii. isopentane (iC5);

xiii. pentane (nC5);

xiv. hexanes +;

xv. Specific gravity; and

xvi. British Thermal Units (BTU).

B. Stable isotope analyses should include:
i. delta D of C1;

ii. delta 13C ofC1;

iii. delta 1 3C of C2;

iv. delta 13C of C3;

v. delta 13C of iC4 (if available);

vi. delta 13C of nC4 (if available);

vii. delta 13C of iC5 (if available);

viii. delta 13C of nC5 (if available); and

ix. delta 13C of CO2.

C. The Operator will notify the Director by submitting a Form 42, Field Operations Notice - Water Sample Reporting, with a copy sent to the owner of the water well immediately if:
i. The test results indicated thermogenic or a mixture of thermogenic and biogenic gas;

ii. The methane concentration increases by more than 5.0 mg/l between sampling periods; or

iii. The methane concentration is detected at or above 10 mg/l.

D. The Operator will notify the Director immediately by Form 42 - Water Sample Report and provide a copy of the Form 42 - Water Sample Report and the test results to the water well owner, if BTEX compounds or TPH are detected in a water sample.

f. Sampling Results. Copies of all final laboratory analytical results will be provided to the Director and the water well owner or landowner within 3 months of collecting the samples. The analytical results including PDF of lab results, the surveyed sample Water Source locations, and the field observations will be submitted to the Director in an electronic data deliverable format approved by the Director along with a PDF of the lab report via Form 43.

(1) The Director will make such analytical results publicly available by posting on the Commission's website or through another means announced to the public.

g. Upon request, the Director will also make the analytical results and surveyed Water Source locations available to the Local Government of the jurisdiction in which the groundwater samples were collected, in the same electronic data deliverable format.

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