Current through Register Vol. 35, No. 11, June 11, 2024
Section 20.6.6.23 - GROUND WATER MONITORING REQUIREMENTS FOR ALL DAIRY FACILITIESA.Monitoring wells- required locations. A permittee shall install a sufficient number of monitoring wells at appropriate depths and locations to monitor ground water quality upgradient of the dairy facility and hydrologically downgradient of each source of ground water contamination: wastewater, stormwater, and combination wastewater/stormwater impoundments, and fields within the land application area. Monitoring wells shall be located pursuant to this section in a location that is protective of the well and to detect an exceedance(s) or a trend towards exceedance(s) of the ground water standards at the earliest possible occurrence, so that source control or abatement may be implemented . (1)Groundwater monitoring - installation schedule.(a) For a new dairy facility, monitoring wells shall be installed before discharging at the dairy facility.(b) For an existing dairy facility, any new monitoring wells shall be installed within 120 days of the effective date of the discharge permit, provided that the department may grant a one-time extension of 60 days for good cause shown.(2) Use of existing monitoring wells. A monitoring well in existence before the effective date of the dairy rule, properly constructed in accordance with department guidelines applicable when the well was constructed, and operating as approved in a previous discharge permit, shall be approved for ground water monitoring at a dairy facility.(3) Exceptions to monitoring well requirements. When appropriate, based on the documented ground water flow direction, one monitoring well may be authorized by a discharge permit to monitor ground water hydrologically downgradient of more than one contamination source under any of the following circumstances.(a) Contiguous impoundments are oriented along a line that is parallel or approximately parallel to the direction of ground water flow beneath the impoundments.(b) Adjacent impoundments are oriented along a line that is parallel or approximately parallel to the direction of ground water flow beneath the impoundments and separated by a distance of 50 feet or less as measured from the top inside edge of one impoundment to the nearest top inside edge of the adjacent impoundment.B. Monitoring wells-location proposals. An applicant or permittee shall identify monitoring well locations in the application for a new, renewed or modified discharge permit pursuant to Subsection A of this section, and shall include the following information.(1) The location of each monitoring well relative to the contamination source it is intended to monitor shall be indicated on the scaled map required by Subsection U of 20.6.6.20 NMAC.(2) A written description of the specific location for each monitoring well including the horizontal map distance (in feet) and compass bearing of each monitoring well from the top inside edge of the impoundment berm or edge of the fields it is intended to monitor.(3) The ground water flow direction beneath the dairy facility used to determine the monitoring well location(s), including supporting documentation used to determine ground water flow direction.C. Monitoring wells-identification tags. A permittee shall identify all monitoring wells required by the dairy rule with a well identification tag. For above-grade wells, the tag shall be affixed to the exterior of the steel well shroud. For wells finished below-grade, the tag shall be placed inside the well vault next to the well riser. The tag shall be printed adhesive or metal: (1) if metal, made of aluminum;(2) at least two inches by four inches in size;(3) for monitoring wells installed after the effective date of the dairy rule, the tag shall include: (a) the discharge permit number;(b) the well identification nomenclature specified in a discharge permit;(c) the name and New Mexico well driller license number of the well driller who drilled the well; and(d) the month and year of well installation; and(4)for monitoring wells installed before the effective date of the dairy rule and satisfying the requirements of Paragraph (6) of Subsection A of this section, the tag shall include:(a) the discharge permit number;(b) the well identification nomenclature specified in a discharge permit; and(c)if available, the name and New Mexico well driller license number of the well driller who drilled the well, and the month and year of well installation.D.Monitoring wells - construction and completion - new monitoring wells. A permittee shall construct monitoring wells pursuant to 19.27.4 NMAC and the following requirements. (1) All well drilling activities shall be performed by an individual with a current and valid well driller license issued by the state of New Mexico pursuant to 19.27.4 NMAC.(2) The well driller shall employ drilling methods that allow for accurate determinations of water table locations. All drill bits, drill rods, and down-hole tools shall be thoroughly cleaned immediately before drilling. The borehole diameter shall allow a minimum annular space of two inches between the outer circumference of the well materials (casing or screen) and the borehole wall to allow for the emplacement of sand and sealant.(3) After completion, the well shall be allowed to stabilize for a minimum of 12 hours before development is initiated.(4) The well shall be developed so that formation water flows freely through the screen and is not turbid, and all sediment and drilling disturbances are removed from the well.(5) Schedule 40 (or heavier) polyvinyl chloride (PVC) pipe, stainless steel pipe, or carbon steel pipe shall be used as casing. The casing shall have an inside diameter not less than two inches. The casing material selected for use shall be compatible with the anticipated chemistry of the ground water and appropriate for the contaminants of interest at the dairy facility. The casing material and thickness selected for use shall have sufficient collapse strength to withstand the pressure exerted by grouts used as annular seals and thermal properties sufficient to withstand the heat generated by the hydration of cement-based grouts.(6) Casing sections shall be joined using welded, threaded, or mechanically locking joints; the method selected shall provide sufficient joint strength for the specific well installation.(7) The casing shall extend from the top of the screen to at least one foot above ground surface. The top of the casing shall be fitted with a removable cap, and the exposed casing shall be protected by a locking steel well shroud. The shroud shall be large enough in diameter to allow easy access for removal of the cap. Alternatively, monitoring wells may be completed below grade. In this case, the casing shall extend from the top of the screen to six to twelve inches below the ground surface; the monitoring wells shall be sealed with locking, expandable well plugs; a fush-mount, watertight well vault that is rated to withstand traffic loads shall be emplaced around the wellhead; and the cover shall be secured with at least one bolt. The vault cover shall indicate that the wellhead of a monitoring well is contained within the vault.(8) A 20-foot section (maximum) of continuous well screen shall be installed across the water table. Screen shall consist of continuous-slot, machine slotted, or other manufactured schedule 40 (or heavier) PVC or stainless steel. Screens created by cutting slots into solid casing with saws or other tools shall not be used. The screen material selected for use shall be compatible with the anticipated chemistry of the ground water and appropriate for the contaminants of interest at the dairy facility. The screen slot size shall be selected to retain 90 percent of the filter pack.(a) Requests for a 30-foot section of continuous well screen may be authorized by a discharge permit when the most recent two years of ground water level data demonstrates a declining water level trend of at least two feet per year. Data supporting ground water levels shall be specific to monitoring wells located at the dairy facility and obtained with a water level measuring device as required by Subsection F of this section.(b) Requests for a 30-foot section of continuous well screen shall be submitted to the department in the application for a new, renewed or modified discharge permit.(9) Screen sections shall be joined using welded, threaded, or mechanically locking joints. The method selected shall provide sufficient joint strength for the specific well installation and shall not introduce constituents that may reasonably be considered contaminants of interest at the dairy facility. A cap shall be attached to the bottom of the well screen. Sumps (i.e., casing attached to the bottom of a well screen) shall not be installed.(10) The bottom of the screen shall be installed no more than 15 feet below the water table, or no more than 25 feet below the water table when additional screen length is authorized by a discharge permit. The top of the well screen shall be positioned not less than five feet above the water table. The well screen slots shall be appropriately sized for the formation materials.(11) Casing and well screen shall be centered in the borehole by installing centralizers near the top and bottom of the well screen.(12) A filter pack shall be installed around the screen by filling the annular space from the bottom of the screen to two feet above the top of the screen with clean silica sand. The filter pack shall be properly sized to exclude the entrance of fine sand, silt, and clay from the formation into the monitoring well. For wells deeper than 30 feet, the sand shall be emplaced by a tremie pipe. The well shall be surged or bailed to settle the filter pack and additional sand added, if necessary, before the bentonite seal is emplaced.(13) A bentonite seal shall be constructed immediately above the filter pack by emplacing bentonite chips or pellets (three-eighths inch in size or smaller) in a manner that prevents bridging of the chips/pellets in the annular space. The bentonite seal shall be three feet in thickness and hydrated with clean water. Adequate time shall be allowed for expansion of the bentonite seal before installation of the annular space seal.(14) The annular space above the bentonite seal shall be sealed with cement grout or bentonite-based sealing material acceptable to the state engineer in accordance with 19.27.4 NMAC. A tremie pipe shall be used to emplace the annular space seal (flow by gravity or pumping through the pipe) if the total depth of the well is greater than 20 feet from the land surface. Annular space seals shall extend from the top of the bentonite seal to the ground surface (for wells completed above grade) or to a level three to six inches below the top of casing (for wells completed below grade).(15) A concrete pad (two-foot minimum radius, four-inch minimum thickness) shall be poured around the shroud or well vault and wellhead. The concrete and surrounding soil shall be sloped to direct rainfall and runoff away from the wellhead.E. Monitoring wells - office of the state engineer requirements. Should a well permit for a monitoring well be required by the office of the state engineer, the permittee shall obtain the permit prior to well drilling.F. Ground water sample collection procedure. A permittee shall perform all ground water sample collection, preservation, transport and analysis according to the following procedure. (1) Depth-to-most-shallow ground water shall be measured from the top of well casing at point of survey to the nearest 0.01 feet using an electronic water level indicator consisting of dual conductor wire encased in a cable or tape graduated to 0.01 feet, a probe attached to the end of the conductor wire, and a visual or audible indicator.(2) Monitoring wells shall be purged before sample collection by one of the following methods. (a) Three well volumes of water shall be purged from the well before sample collection.(b) The monitoring well shall be purged until measurements of indicator parameters (pH, specific conductance, and temperature) have stabilized. Indicator parameters shall be measured periodically during purging. A parameter stabilization log shall be kept during each sampling event for each monitoring well and include: date; water quality indicator parameter measurements; time for all measurements; and the purge volume extracted. Indicator parameters are considered stable when three consecutive readings made no more than five minutes apart fall within the following ranges: temperature plus or minus 10 percent; pH plus or minus 0.5 units; specific conductance plus or minus 10 percent.(3) Following purging and immediately before sample collection the following fields parameters shall be measured and recorded: pH, specific conductance, and temperature.(4) In-line flow-through cells shall be disconnected or bypassed during sample collection, if used during purging.(5) Samples from the well shall be obtained, prepared, preserved and transported to an analytical laboratory for analysis pursuant to the methods authorized by Subsection B of 20.6.6.24 NMAC.G.Ground water sampling and reporting - routine. A permittee shall collect ground water samples quarterly from all monitoring wells required by Subsection A of this section and Subsection C of 20.6.6.27 NMAC. Samples shall be analyzed for nitrate as nitrogen, total Kjeldahl nitrogen, chloride, sulfate and total dissolved solids pursuant to Subsection B of 20.6.6.24 NMAC. A permittee shall submit to the department in the quarterly monitoring reports the depth-to-most-shallow ground water, the fields parameter measurements, the parameter stabilization log (if applicable), the analytical results (including the laboratory quality assurance and quality control summary report) and a map showing the location and number of each well in relation to the contamination source it is intended to monitor.H.Ground water sampling - new monitoring wells. A permittee shall collect ground water samples from all newly installed monitoring wells. Samples shall be analyzed for nitrate as nitrogen, total Kjeldahl nitrogen, chloride, sulfate and total dissolved solids pursuant to Subsection B of 20.6.6.24 NMAC. (1) Samples shall be collected from the newly installed monitoring wells at new dairy facilities before placing livestock at the dairy facility.(2) Samples shall be collected from the newly installed monitoring wells at existing dairy facilities within 150 days of the effective date of the discharge permit.(3) For dairy facilities installing a new monitoring well during the term of a discharge permit, during construction of a new impoundment, or as a result of required corrective actions, samples shall be collected from the newly installed monitoring wells within 30 days of well completion, provided the department may grant an extension for good cause shown. I.Monitoring well survey and ground water flow determination. A permittee shall survey monitoring wells to a U.S. geological survey (USGS) benchmark and State Plane coordinates. Survey data shall include northing, easting and elevation to the nearest hundredth of a foot or shall be in accordance with the "Minimum Standards for Surveying in New Mexico", 12.8.2 NMAC. A survey elevation shall be established at the top-of-casing, with a permanent marking indicating the point of survey. The survey shall be completed and bear the seal and signature of a licensed New Mexico professional surveyor. Depth-to-most-shallow ground water shall be measured from the point of survey to the nearest hundredth of a foot in all surveyed wells pursuant to Subsection F of this section, and the data shall be used to develop a map showing the location of all monitoring wells and the direction and gradient of ground water flow at the dairy facility. (1) For a new dairy facility, monitoring wells shall be surveyed before placing livestock at the dairy facility.(2) For an existing dairy facility, monitoring wells not previously surveyed in a manner consistent with the requirements of this subsection and Subsection B of 20.6.6.17 NMAC shall be surveyed within 150 days of the effective date of the discharge permit.J.Monitoring well completion report. A permittee shall submit to the department a monitoring well completion report pertaining to all monitoring wells. For a new dairy facility, the report shall be submitted before placing livestock at the dairy facility. For an existing dairy facility, the report shall be submitted within 180 days after the effective date of the discharge permit or within 60 days of completion as specified in a discharge permit. The report shall contain the following information.(1) Construction and lithologic logs for the new monitoring wells including well record information specified by 19.27.4 NMAC.(2) Depth-to-most-shallow ground water measured in each new and existing monitoring well.(3) Survey data and a survey map showing the locations of each new and existing monitoring well and a ground water elevation contour map developed pursuant to Subsection L of this section.(4)Analytical results of ground water samples collected from the new monitoring wells, including laboratory quality assurance and quality control summary reports, and fields parameter measurements.K.Monitoring wellsurvey report - existing monitoring wells. For a dairy facility required to survey existing monitoring wells pursuant to this section a permittee shall submit the monitoring well survey report to the department within 180 days of the effective date of the discharge permit, provided the department may grant an extension for good cause shown. The report shall contain the depth-to-most-shallow ground water measured in each monitoring well, a surveyed map showing the locations of the monitoring wells, and the direction and gradient of ground water flow at the dairy facility.L.Ground water elevation contour maps. A permittee shall develop ground water elevation contour maps on a quarterly basis using data associated with all monitoring wells used for ground water monitoring at the dairy facility. Top of casing elevation data, obtained from monitoring well surveys completed pursuant to this section and quarterly depth-to-most-shallow ground water measurements in monitoring wells, shall be used to calculate ground water elevations at monitoring well locations. Ground water elevations between monitoring well locations shall be estimated using common interpolation methods. Ground water elevations shall be expressed in feet. A contour interval appropriate to the data shall be used, but in no case shall the interval be greater than two feet. Ground water elevation contour maps shall depict the ground water flow direction, using arrows, based on the orientation of the ground water elevation contours, and the location and identification of each monitoring well, impoundment, and fields within the land application area. A permittee shall submit ground water elevation contour maps to the department in the quarterly monitoring reports.M. Proposed location of monitoring wells - dispute resolution. If the department provides a notice of technical deficiency pursuant to Subsection G of 20.6.6.10 NMAC due to a disagreement with the number or location of monitoring wells proposed in the application, or if the department notifies a permittee to replace a monitoring well pursuant to Subsection C of 20.6.6.27 NMAC, the applicant or permittee may notify the secretary by certified mail, sent within 30 days after the date of postal notice of the department's notice, that the applicant or permittee invokes dispute resolution under this subsection. Upon such notice, the department, as represented by the secretary, deputy secretary, or division director and the applicant or permittee shall meet in person within 30 days and shall attempt in good faith to resolve the dispute.20.6.6.23 NMAC - N, 1/31/2011; A, 12/31/2011Amended by New Mexico Register, Volume XXVI, Issue 11, June 16, 2015, eff. 6/16/2015