Wellhead Protection for New Community Water Supply Wells
What
The Illinois EPA is expanding procedures for gathering driller's logs
and safe yield information during the development of new community water
supply wells. This brochure outlines a step-by-step approach for obtaining
this information when installing new wells.
Why
Once the Illinois EPA receives this new well data, a delineated Source
Water Protection Area and lateral area of influence calculation will
be provided to the community. This information can then be utilized
as the technical support to initiate:
- maximum setback zones;
- eligibility for chemical monitoring reform/permanent monitoring
relief;
- lab fee savings;
- prevention programs including the pollution prevention and conservation
reserve programs
Who
Community water supply systems expanding through the construction of
new wells are required to initiate local wellhead protection programs
for these wells. Traditionally this has included assurance that wells
are properly engineered to protect against sanitary contamination. In
September 1987, protection was expanded to include siting prohibitions
for new drinking water wells locating proximate to certain high risk
activities. Further, under 35 Ill Adm. Code Section 653.103(a)1, community
water supplies are required to conduct safe yield and drawdown tests.
1"The basic criteria for design of community water
supply facilities shall be the Standards (Recommended Standards for
Water Works as adopted by the Great Lakes-Upper Mississippi River Board
of Sanitary Engineers)."
When
Delineation of the wellhead protection areas can be accomplished more
readily and more economically at this time because much of the hydrogeologic
and well production information that is gathered can also be used for
resource assessment.
The First Step
An inventory of potential sources and routes of contamination must
be conducted within 1,000 feet of a new community water supply well.
This must be completed prior to issuance of a permit to construct a
water supply well ("C-1 Permit") by the Illinois EPA.
The Second Step
Yield and drawdown tests must be performed on every production well
after construction or subsequent treatment and prior to placement of
the permanent pump and issuance of an operating permit ("C-II Permit")
by the Illinois EPA. The best possible information should be collected
on the new community water supply well. This information must include
the static and pumping water level information used in calculating drawdown.
Further, detailed information and supporting documentation must be provided
in the calculation of a long-term safe yield for the new well.
The Third Step
Supply the Illinois EPA the following information, specific to the
new well under development:
- driller's and/or correlated well logs;
- regional groundwater flow direction (if available or conducted);
- results
of tritium analysis (if available or conducted);
- static water level;
- depth of pump setting;
- test pump capacity - head characteristics;
- time of starting and ending each test cycle (preferably at least
six hours with stable drawdown at a continuous pumping rate, normally
1.5 times the designed pumping rate);
- pumping water level at the end of the test cycle;
- pumping rate; and
- water recovery rate and levels
In certain instances an aquifer test may be necessary to assess the
effects of well interferences, determine if groundwater recharge area
boundaries exist, or to assess an aquifer's long-term safe yield or
vulnerability with respect to potential contamination sources. Once
the Illinois EPA receives this data, a determination will be made on
the degree of natural geologic protection afforded the well. Depending
on the type of aquifer being utilized as a source, a confined or unconfined
determination will be provided to the community.
The Final Step
(for community water supply wells participating in the Safe Drinking
Water Act Phase II, II(b), and V monitoring waiver program):
Once operation of the new well is initiated, Community Water Supplies
shall complete at least one set of laboratory analysis for volatile/synthetic
organic and inorganic chemicals from the new untreated source. Upon
completion of these analyses, the community water supply must file a
revision to their waiver application, with all relevant information
(including any necessary wellhead protection management activities)
with the Illinois EPA.
