Dry Well
Services
Dry wells are a common means of storm water management in the southwestern deserts.
Dry wells are designed to receive storm water runoff and allow the waters to
percolate into the subsurface soils well above the regional aquifer. Environment
Technology, Inc. (EN TECH®) provides a full line of dry well
services for owners of existing dry wells or property owners seeking storm water
management solutions. Dry wells are required to be registered in the State of
Arizona and are regulated by the ADEQ under the Aquifer protection program (APP).
Dry Well Registration Assistance
All persons who own an existing dry well or who plan to install a dry well are required to
register the dry well with the Arizona Department of Environmental Quality (ADEQ).
Dry wells are also required to be registered prior to decommissioning. EN TECH®
can assist dry well owners in the registration procedures.
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Percolation Testing and Subsurface Characterization
Effective storm water management requires an understanding of drainage patterns and
subsurface permeability for percolation of storm water disposal. It is also
important to direct storm water away from areas where chemicals are used, transferred or
stored that could contaminate the water. EN TECH®'s
geologists and engineers provide site drainage evaluations and design. Percolation
tests are performed on subsurface soils to evaluate soil permeabilities and capacity of
the soils to absorb storm water disposal from dry wells. These studies assist in the
effective design of storm water management systems.
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Design and Installation
Dry well designs incorporate several factors including:
- the anticipated volume of storm water
- the drainage area feeding the dry well
- information on historical precipitation events
- characteristics of the drainage surfaces (e.g. concrete, asphalt, grass, dirt)
- the types and distribution of subsurface soils
- the permeability and storage capacity of the subsurface soils
- the depth and local use of groundwater
- site usage and chemical storage
EN TECH® evaluates these factors in determining the need for
retention basins, pretreatment equipment and designing the number, location, size, depth
and sediment handling capacity of the dry wells. The ADEQ requires dry wells be
installed by a licensed dry well driller. EN TECH® works
closely with several licensed drillers in the specification and installation of dry wells.
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Aquifer Protection Permit - Determination of
Applicability
Dry wells may be regulated under the Aquifer Protection Permit (APP) program of the ADEQ
when they are in areas where hazardous materials are used, stored, loaded or treated or
when they receive discharges other than storm water (e.g. industrial wastewater injection
wells). The determination as to whether a dry well is regulated under this program
rests with the ADEQ. The ADEQ may supply the dry well owner with a Determination of
Applicability form to be completed for their review in determining if an APP is required.
EN TECH® assists our clients in the collection of data
and preparation of the determination of applicability form.
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Aquifer Protection Permit Application and Regulatory
Liaison Services
The APP requirements apply to dry wells that drain areas where hazardous substances are
used, stored, loaded or treated. The APP is used to ensure that best management
practices are followed and that no hazardous substances enter the dry well. The ADEQ
may require dry well owners apply for an APP after review of the determination of
applicability form.
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Best Management Practices Plan (BMPP)
The APP may require that the dry well owner develop a Best Management Practices Plan
(BMPP) in order to minimize the possibility of contaminating soil, groundwater or surface
water from contaminated runoff. This plan is typically only applicable to industrial
or commercial properties that use, store, load or treat hazardous substances.
Discharge of any contaminant resulting in a violation of the Aquifer Water Quality
Standard (AWQS) is prohibited by State law.
Some factors to consider in developing a BMPP include:
- Types of hazardous substances present and how they are used
- Exterior and interior locations of storage, use and/or treatment areas
- Site drainage patterns
- Spill containment structures
- Spill response procedures; containment, cleanup and waste disposal
- Waste management and housekeeping procedures including containerization, waste
minimization and recycling/reuse
- Dry well maintenance practices
- Employee training; chemical handling, spill response and waste disposal
- Pretreatment and alternative discharge options
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Investigations and Sampling
If a dry well owner suspects contamination or is directed by the ADEQ to perform an
investigation of the dry well, EN TECH® can develop and
implement a dry well investigation to evaluate the presence and extent of
contamination. EN TECH®'s investigation procedures are
designed to address the concerns of the ADEQ while being cost-effective to our
clients. The ADEQ may require an investigation of a dry well prior to
abandonment. The investigation process is summarized in the Dry well Investigative
Screening Process Chart and may involve some or all of the following:
- Collection and analysis of sediment samples from the dry well settling chamber
- Background information on dry well construction, pretreatment, subsurface soils, surface
water, groundwater depth and flow direction
If sample results are above ADEQ guidance levels for dry well sediment samples,
additional investigations may be required including the following:
- Settling chamber clean out
- Drilling an investigative soil boring adjacent to the dry well, log the soil profile,
collect soil samples and determine the vertical extent of soil contamination, if any
- Analyze soil samples for contaminants of concern and compare with Groundwater Protection
Levels (GPLs)
If soil samples collected from the soil boring exceed the GPLs, a groundwater
investigation may be required after evaluation of the vertical extent of soil
contamination and the depth to groundwater. Soil and/or groundwater remediation may
be required if contamination is present above regulatory levels.
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Abandonment and Clean Closure
EN TECH® can assist the dry well owner in the proper
registration notification, investigation and abandonment procedures for dry well
decommissioning. Clean closures do not require an APP permit. However, a dry
well investigation may be required prior to closure to satisfy clean closure requirements.
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