W. Va. Code R. § 47-60-17

Current through Register Vol. XLI, No. 45, November 8, 2024

Section 47-60-17 - Well Development, Redevelopment and Reconditioning

All permanent monitoring wells shall be developed according to the requirements of this section, except for excavated wells and wells that are installed for the sole purpose of determining the level of groundwater or the potentiometric surface. Wells sealed with grout or slurry shall be developed after a minimum waiting period of twelve (12) hours after installation is completed. Development, redevelopment and/or reconditioning operations shall be performed with care, so as to prevent damage to the well and any strata surrounding the well. Care is necessary to prevent the spread of contaminants, particularly when the well is situated in known or suspected areas of contamination. The goal of well development is to produce water free of sediment and all drill cuttings and drilling fluids. Appropriate methods of well development vary with the type and use of a monitoring well. Development methods that may be acceptable under certain circumstances include:

17.1. Methods for wells that cannot be purged dry. -- All permanent monitoring wells that cannot be purged dry shall be developed until a minimum of ten (10) well volumes of water are removed or until the well produces sediment free water. Well volumes shall be calculated in the manner prescribed in Table 1 of this rule. One or more of the following methods shall be used to develop a well under this section:

17.1.a. Surge and Purge Method. -- The surge and purge cycle shall consist of several minutes of surging followed by several minutes of purging to remove the material collecting in the bottom of the well. The surging shall move formation water in and out of the well screen. The surging shall be accomplished by using a bailer, surge block or by pumping the well sufficiently to cause a drawdown and then allowing the well to recover and repeating the process. Plungers, bailers, surge blocks, and other surging devices must incorporate safety valves or vents to prevent excessive pressure differentials that could damage casing, screen, or the formation. The positive and negative pressures exerted shall not force contaminants from or into the well bore, cause mechanical damage to the well components, draw annular space or filter pack sealant into the filter pack, bridge the filter pack with excessive sediments, or collapse the formation.

17.1.b. Over Pumping (Pump Surging Method). -- The monitoring well shall be pumped at a rate considerably higher than it would be during normal operation to dislodge fine-grain materials from the filter pack and surrounding strata. This method also requires mechanical surging in order to delete the negative influences associated with one directional movement of water. This method may not be suitable for wells producing large amounts of sediment that could jam or clog a pump. Over pumping can also create a cone of depression in the water table that can draw contaminants to the well.

17.1.c. Air Lift Pumping Method. -- An air lift pump shall be operated by cycling the air pressure on and off for short periods of time to provide a surging action that will dislodge fine-grained materials from the filter pack and surrounding strata. A steady, low pressure shall be applied to remove the fines that have been drawn into the well by the surging action. Efforts should be made (through the use of a foot valve) to avoid pumping air into the filter pack and adjacent hydrologic unit because the air may lodge there and inhibit future sampling efforts and may also alter ambient water chemistry. Furthermore, application of high air pressures should be avoided to prevent damage to PVC risers, screens, and filter packs. The use of an eductor pipe is recommended. Operational air must be free of oil or other contaminants through use of a coalescing filter.

17.1.d. Well Jetting Method. -- The well screen area shall be jetted with water using sufficient pressure to achieve the desired effect but limiting force to prevent damage to the well components and surrounding formation. Water added during this development procedure will alter the natural, ambient water quality and may be difficult to remove. Therefore, the water added should be obtained from an uncontaminated source. Water from the monitoring well being developed may also be used if the suspended sediments are first removed.

17.2. Methods for Wells that Can Be Purged Dry. All permanent monitoring wells that can be purged dry shall be developed in a manner that limits agitation by slowly purging the well dry. Any water added for development shall be from an uncontaminated source, and an equal volume of water shall be purged upon completion of development.

W. Va. Code R. § 47-60-17