West Virginia Code of State Rules › Agency 47 - Water Resources, Division Of Water And Waste Management › Title 47 - LEGISLATIVE RULE DEPARTMENT OF ENVIRONMENTAL PROTECTION DIVISION OF WATER RESOURCES › Series 47-60 - Monitoring Well Design Standards › Section 47-60-17 - Well Development, Redevelopment and Reconditioning

Current through Register Vol. XLI, No. 28, July 12, 2024
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.