Minimum Design, Installation, Monitoring, Maintenance & Recordkeeping Standards
Authorized By Rule UIC Class V well owners are authorized by the Underground Injection Control (UIC) regulations (310 CMR 27.00) to continue operating existing UIC Class V injection wells or to construct and operate new wells if the following conditions are met:
- Existing wells were inventoried and registered with Massachusetts Department of Environmental Protection (MassDEP) by January 1st 2003 and new injection wells are registered with MassDEP prior to their installation and operation.
- For any existing or proposed well that has not yet received a UIC Registration Number from MassDEP, a system evaluation has been conducted for existing injection wells, to verify that the discharge meets the following criteria and proposed new wells shall meet these same criteria:
- Only the approved discharge that is listed on the MassDEP UIC registration approval letter shall be discharged to the Class V UIC well unless such discharge has been approved by MassDEP through a separate registration or permit approval.
- All ground source heat pump (GSHP) wells adhere to the MassDEP Guidelines for Ground Source Heat Pump Wells.
- No wastewater (agricultural, industrial, sanitary, etc.) shall be discharged into a stormwater infiltration system.
- Site design, development, construction, and management practices are implemented to minimize the presence of contaminants in the discharge and to maximize the protection of groundwater quality.
- No existing soil or groundwater contamination will be affected by the UIC Class V injection (i.e. soil contamination will not be mobilized either directly from the discharge or indirectly from the water table mounding that will result from the discharge and groundwater contaminant plumes will not migrate or expand as a result of the Class V UIC injection).
- Discharge does not occur directly into groundwater or below the highest seasonal groundwater table (with the exception of discharges from a ground source heat pump (GSHP) well).
- A natural or engineered filtration medium is present between the base of the injection well and the highest seasonal groundwater table elevation that minimizes the potential for contaminants from reaching groundwater OR best management practices (BMPs) have been implemented to remove contaminants prior to reaching the injection well.
- Spill control is present, including the ability to temporarily block discharge in the event of a spill (not required if there is no potential for spill of a contaminant).
- Storm water injection wells adhere to the Massachusetts Stormwater Handbook requirements and a UIC Technical Compliance Form for Stormwater Wells has been completed and submitted to MassDEP UIC Program.
- No contamination is present in the discharge to the UIC well above reportable concentration limits for groundwater as specified in the Massachusetts Contingency Plan (MCP). There are limited exceptions for construction dewatering discharges at oil/hazardous waste sites but additional limitations and conditions apply and are determined on a case-by-case basis.
- See the Instructions for Underground Injection Control Stormwater Technical Compliance Form for additional requirements for stormwater UIC wells.
Minimum Setback Distances
All Class V UIC wells must conform to the following minimum setback distances, measured in feet and as set forth below. Where more than one setback applies, all setback requirements shall be satisfied.
| Property Feature | Any Pre-treatment Device (i.e. oil/water separator) (feet) | Class V Well (feet) |
|---|---|---|
| Property Line | 10 | 10 |
| Swimming Pool (in-ground) or Foundation Drain | 10 | 20 |
| Building foundation (including slabs) | 10 to 20 [1] | |
| Water Supply Line | 10 | 10 |
| Surface Waters (except wetlands) | 25 | 50 to 150 [2] |
| Bordering Vegetated Wetland (BVW), Salt Marshes, Inland and Coastal Banks | 25 | 50 |
| Surface Water Supply - Reservoirs and Impoundments and tributary rivers and streams | Outside Zone A | Outside Zone A |
| Wetlands bordering Surface Water Supply or Tributary thereto | 100 | 100 |
| Certified Vernal Pools | 50 | 100[3] |
| Private Water Supply Well or Suction Line | 50 | 100[4] |
| Public Water Supply Well | Outside Zone I | Outside Zone I |
| Irrigation Well and other non-drinking water production wells | 10 | 25 |
| Open, Surface or Subsurface Drains which discharge to Surface Water Supplies or tributaries thereto | 50 | 100 |
| Other Open, Surface or Subsurface Drains (excluding foundation drains) which intercept seasonal high groundwater table [3] | 25 | 50 |
| Other Open, Surface or Subsurface Drains (excluding foundation drains) | 5 | 10 |
| Other subsurface discharge structures such as leaching catch basins, dry wells, drainfields, leaching chambers, etc. and any surface recharge system approved pursuant to Wetlands Protection Act | 10 | 25 to 100 [5] |
| Activity Use Limitation (AUL) | Must meet any requirements of the AUL | Outside AUL [6] |
| Downhill Slope | not applicable | 15[7] |
[1] The minimum required setback distance for most types of UIC wells shall be 10 feet. However, based upon the type of foundation structure and the foundation drainage system, the UIC well designer shall be responsible for determining whether a greater setback distance is required based upon the anticipated maximum groundwater elevation mound height that will be created by the discharge to the UIC well. The minimum required setback for most types of stormwater UIC wells (i.e. dry wells and leaching chambers) is also 10 feet. However, the setback distances for stormwater trenches (which are considered UIC wells if backfilled with filter sand or stone) is 20 feet.
[2] The required setback distance for most types of UIC wells shall be 50 feet including most types of stormwater wells (i.e. dry wells and leaching chambers). However, the setback distances for stormwater trenches is 100 feet upslope and 150 feet downslope of a surface water body.
[3] The required setback shall be 50 feet where the applicant has provided hydrogeologic data acceptable to MassDEP demonstrating that the location of the Class V UIC well is hydraulically downgradient of the Certified Vernal Pool. Surface topography alone is not determinative.
[4] See MassDEP Guidelines for Ground Source Heat Pump Wells for applicable private well setback distances for these types of wells.
[5] See MassDEP Guidelines for Ground Source Heat Pump Wells for applicable setback distances to soil absorption systems (leaching fields). A 50-foot setback distance from Title 5 (310 CMR 15.00) soil absorption systems applies to all stormwater UIC wells. Stormwater UIC well setback distances to other types of subsurface discharge structures shall be the same as the following descriptions that apply to all other UIC wells. If the UIC well (except motor vehicle rinse water wells) has a proposed maximum daily discharge rate of less than 2,000 gallons per day (gpd) then a 25-foot setback to other discharges applies. If the proposed maximum daily discharge rate is 2,000 gpd or greater, or if the well is a motor vehicle rinse water well, then a 100-foot setback to other discharges applies.
[6] Exceptions will be considered by MassDEP on a case-by-case basis and will generally require that additional conditions are met.
[7] The setback distance shall be measured from a naturally-occurring downhill slope which is not steeper than 3:1 (horizontal:vertical). A minimum 15-foot horizontal separation distance shall be provided between the top of the infiltration structure (i.e. top of drainage pipe or leaching chamber or dry well, etc.) and the adjacent downhill slope. For a system located in an area with any adjacent naturally occurring downhill slope steeper than 3:1, slope stabilization shall be provided in accordance with best engineering practice which may include construction of a concrete retaining wall designed by a Massachusetts Licensed Professional Engineer (PE).
All setback distances from water bodies shall be measured from the bank of the water body. All setback distances from wetlands shall be measured in accordance with the criteria of the wetlands protection act and 310 CMR 10.00, from the most landward edge of the following features: bordering vegetated wetland as defined in 310 CMR 10.55(2); salt marsh as defined in 310 CMR 10.32(2); top of inland bank as defined in 310 CMR 10.54(2); or top of coastal bank as defined in 310 CMR 10.30(2). In the event of disputes concerning landward boundary of resources subject to the Wetlands Protection Act, the boundary shall be as delineated by the municipal Conservation Commission or MassDEP in accordance with 310 CMR 10.00, as amended, and relevant interpretive guidance documents.
Although there are no specified setback distances for underground storage tanks (UST) or industrial wastewater holding tanks (IWHT), the UIC Class V well shall, at minimum, be kept a safe distance from any UST or IWHT to prevent the potential of damage to the integrity of the UST or IWHT system (including the tank foundation and all connection piping) during the well installation and operation. That safe distance shall take into account an assessment as to whether the existing or proposed UIC well discharge has the potential to result in a mounding of the groundwater elevation that may uplift the UST or IWHT when empty.
Depth Requirements
(1) The minimum vertical separation distance between the base of the Class V UIC well (measured from base of filter sand or stone placed beneath UIC well (if applicable)) and the seasonal high groundwater (water table) elevation shall be:
(a) two feet for all stormwater wells;
(b) four feet for all other types of UIC Class V wells;
(c) where the percolation rate is two (2) minutes or less per inch , the designer shall consider the potential contaminants that may enter the UIC well and shall assess whether additional pre-treatment may be necessary to reduce the risk of contaminating the groundwater; and,
(d) For a non-stormwater UIC Class V well with a maximum daily proposed discharge rate of 2,000 gallons per day or greater, the calculated groundwater mounding that will occur as a result of the proposed maximum daily discharge must be added to the seasonal high groundwater elevation for determining the minimum vertical separation distance. The number of continuous days of discharge used for the groundwater mounding calculations shall be determined based upon the nature of the proposed discharge. For example, daily discharges occurring at or near maximum daily discharge volume nearly every day for weeks or months would be modeled for weeks or months of continuous discharge; whereas, if the maximum daily discharge only occurred on an intermittent basis (i.e. once per week), the discharge would be modeled for an appropriately shorter time period.
Evidence of seasonal high groundwater (water table) elevation shall be provided in the UIC registration application submittal package. Groundwater mounding calculations shall also be provided for all non-stormwater UIC wells with maximum daily proposed discharge rates of 2,000 gallons per day or greater.
(2) The minimum vertical separation distance between the base of the Class V UIC well and bedrock shall be five (5) feet.
Laboratory Analytical Requirements
If laboratory analytical results are required for your well type you shall submit copies of the original laboratory analytical reports unless you are a public water supplier (PWS) and have previously submitted those reports to the MassDEP Drinking Water Program. If you are a PWS and have previously submitted the results, you shall be required to indicate in your UIC Registration application package the results of the relevant testing (most recent test results) but will generally not be required to send copies of the actual laboratory reports. Note that additional laboratory analyses may be required for any type of UIC well(s) depending upon site specific and/or proposed discharge specific concerns.
| UIC Well Type | Laboratory Analytical Requirements |
| Ground Source Heat Pumps (GSHP) | See GSHP guidelines [1] |
| Special Drainage - Swimming Pool | Dechlorination test results indicating chlorine as Cl2less than or equal to 4.0 milligrams per liter (mg/L) |
| Aquaculture Return Flow | Sodium, chloride, and total coliform bacteria (including fecal coliform and E. coli) |
| Water Purification Wells (commercial, industrial, public water system, and residential) | Raw water quality results.[2] |
| Non-Contact Cooling Water Return Flow | Additive concentrations (if applicable) |
| Experimental Technology | Considered on a case-by-case basis |
| Closure (All types of UIC wells) | Depends upon the specific well type and site history [3] |
[1] See MassDEP Guidelines for Ground Source Heat Pump Wells for applicable laboratory analytical requirements for these types of wells.
[2] Any raw water results for contaminants that are being treated or that exceed public drinking water standards or may be expected to exceed public drinking water standards when concentrated in the water purification discharge to the UIC well.
[3] All UIC Well Closures must be done in accordance with Massachusetts Closure Requirements for Underground Injection Control (UIC) Wells (including shallow injection wells) (MassDEP Guidance #: BRP/DWM/DW/G04-3) . The laboratory analytical testing requirements depend upon the type of well being closed and the types of contaminants that had the potential to enter the well. The specific laboratory analytical testing requirements discussed in MassDEP Guidance #: BRP/DWM/DW/G04-3 are for Motor Vehicle - Waste Disposal wells. Some or all of those testing requirements may also apply to Motor Vehicle - Rinse Water wells depending upon the types of best management practices (BMP) that were in place throughout the time that the well was in use. Those specific analytical testing requirements may not apply to the closure of other well types.