Current through August 31, 2023
Written approval by the Department is required before water
from any new or reconstructed well may be served to the public. Any supplier of
water for a public water system served by one (1) or more wells shall ensure
that the following requirements are met: (3-24-22)
01.
Site Approval. Prior to
drilling, the site of a public water system well must be approved in writing by
the Department. The Department shall require the supplier of water to submit a
well site evaluation report that takes into account the proposed size, depth,
and location of the well. The evaluation may include, but is not limited to the
following types of information: (3-24-22)
a.
An evaluation of the quality of anticipated ground water. (3-24-22)
b. Identification of the known aquifers and
the extent of each aquifer, based on the stratigraphy, sedimentation, and
geologic structure beneath the proposed well site. (3-24-22)
c. An estimate of hydrologic and geologic
properties of each aquifer and confining layers. (3-24-22)
d. Prediction of the sources of water to be
extracted by the well and the drawdown of existing wells, springs, and surface
water bodies that may be caused by pumping the proposed well. This prediction
may be based on analytical or numerical models as determined by the Idaho
Department of Water Resources permitting process. (3-24-22)
e. Demonstration of the extent of the capture
zone of the well, based on the well's design discharge and on aquifer geology,
using estimates of hydraulic conductivity and storativity. (3-24-22)
f. Description of potential sources of
contamination within five hundred (500) feet of the well site.
(3-24-22)
02.
Location. Each well shall be staked by the design engineer or
licensed professional geologist prior to drilling, be located a minimum of
fifty (50) feet from the nearest property line, be located a minimum of fifty
(50) feet from any potential source of contamination, and be no closer to
specified sources of contamination than set forth in Subsection
900.01. In vulnerable settings,
the Department may require engineering or hydrologic analysis to determine if
the required setback distance is adequate to prevent contamination.
(3-24-22)
03.
Construction
Standards. In addition to meeting the requirements of these rules, all
wells shall be constructed in accordance with IDAPA 37.03.09, "Well
Construction Standards Rules," and related rules and laws administered by the
Idaho Department of Water Resources. All wells shall comply with the drilling
permit requirements of Section
42-235, Idaho Code. (3-24-22)
a. Casing that meets the requirements set
forth in Subsection 900.02
(Table 2). The use of plastic well casing for public water system wells may be
considered on a case-by-case basis. Plastic casing shall meet or exceed ASTM
Standard F480-02 and ANSI/NSF Standard 61. (3-24-22)
b. Public water system wells shall have no
less than fifty-eight (58) feet of annular seal of not less than one and
one-half (1
1/2) inches
thickness as measured from land surface to the bottom of the seal unless:
(3-24-22)
i. It can be demonstrated to the
Department's satisfaction that there is a confining layer at lesser depth that
is capable of preventing unwanted water from reaching the intake zone of the
well; or (3-24-22)
ii. The best and
most practical aquifer at a particular site is less than fifty-eight (58) feet
deep; or; (3-24-22)
iii. The
Department specifies a different annular seal depth based on local hydrologic
conditions. (3-24-22)
iv. More
stringent standards are required by applicable Rules of the Idaho Water
Resources Board, referenced in Subsection
002.02.
(3-24-22)
c.
Specifications shall include allowable tolerances for plumbness and alignment
in accordance with AWWA Standards, incorporated by reference into these rules
at Subsection 002.01, or
as otherwise approved by the Department. If the well fails to meet these
requirements, it may be accepted by the Department if it does not interfere
with the installation or operation of the pump or uniform placement of grout.
(3-24-22)
d. Geological data shall
be collected at each pronounced change in formation and shall be recorded in
the driller's log. Supplemental data includes, but is not limited to, accurate
geographical location such as latitude and longitude or GIS coordinates, and
other information on accurate records of drillhole diameters and depths,
assembled order of size and length of casing, screens and liners, grouting
depths, formations penetrated, and water levels. (3-24-22)
e. The owner of each well shall retain all
records pertaining to each well until the well has been properly abandoned.
(3-24-22)
f. Wells with intake
screens shall: (3-24-22)
i. Be constructed of
materials resistant to damage by chemical action of ground water or cleaning
operations. (3-24-22)
ii. Have
openings based on sieve analysis of formation or gravel pack materials.
(3-24-22)
iii. Have sufficient
length and diameter to provide adequate specific capacity and aperture entrance
velocity not to exceed point three (0.3) feet per second, or as otherwise
approved by the Department. (3-24-22)
iv. Be installed so that the pumping water
level remains above the screen under all operating conditions, or otherwise
approved by the Department. Where a bottom plate or sump is utilized, it shall
be of the same material as the screen, or as otherwise approved by the
Department. Where a washdown assembly, tailpipe or sump is used below the
screen, it may be made of a different material than the screen.
(3-24-22)
g. Permanent
well casing shall be surrounded by a minimum of one and one-half (1 ½ )
inches of grout to the depth required by Subsection
510.03.b. of these rules, or
by the Rules of the Idaho Water Resources Board referenced in Subsection
002.02, whichever is greater.
All casing identified in plans and specifications as temporary casing shall be
removed prior to well completion. (3-24-22)
i. Neat cement grout consisting of cement
that conforms to AWWA Standard A-100, and water, with not more than six (6)
gallons of water per ninety-four (94) pounds of cement, shall be used for one
and one-half (1 ½) inch openings. Additives may be used to enhance
effectiveness and are subject to approval by the reviewing authority and the
Idaho Department of Water Resources on a case-by-case basis.
(3-24-22)
ii. Bentonite grout shall
have a solids content not less than twenty-five (25) percent by weight when
mixed with water and be specifically manufactured for use in sealing of well
casing. Bentonite grout shall not contain weighting agents to increase solids
content. Bentonite grout shall not be used above the water table. All bentonite
grout shall be installed by positive displacement from the bottom up through a
tremmie or float shoe. (3-24-22)
iii. Where a dry annular space is to be
sealed, a minimum of two (2) inches on all sides of the casing shall be
required to place bentonite to depths not greater than one hundred (100) feet,
using #8 mesh granular bentonite. All dry pour granular bentonite shall be
tagged at appropriate intervals to verify placement. If a bridge occurs, a
tremmie pipe shall be washed or jetted through the bridge to allow for pumping
of grout. Bentonite chips shall be of sufficient size to accommodate proper
placement for the existing subsurface conditions. (3-24-22)
iv. Dry granular bentonite used in wells
where a dry annular space is to be sealed with depths greater than one hundred
(100) feet shall require an annulus of at least three (3) inches on all sides
of the casing, or as approved by the reviewing authority and the Idaho
Department of Water Resources. If a bridge occurs, a tremmie pipe shall be
washed or jetted through the bridge to allow for pumping of grout. Bentonite
chips shall be of sufficient size to accommodate proper placement for the
existing subsurface conditions. (3-24-22)
v. All chip bentonite seals installed through
water shall only be used in annular spaces of at least four (4) inches on all
sides of the casing. If a bridge occurs, a tremmie pipe shall be washed or
jetted through the bridge to allow for pumping of grout. Bentonite chips shall
be of sufficient size to accommodate proper placement for the existing
subsurface conditions. Chip bentonite seals installed through water shall be:
(3-24-22)
(1) Installed in accordance with
manufacturer's specifications; or (3-24-22)
(2) Installed by pouring chips over a
one-quarter (1/4) inch mesh screen for three-eighths (3/8) inch chips to remove
fines to prevent bridging at the water table; or (3-24-22)
(3) Installed using coated pellets to retard
hydration if approved by the reviewing authority and the Idaho Department of
Water Resources. (3-24-22)
vi. Concrete may be approved on a
case-by-case basis by the reviewing authority and the Idaho Department of Water
Resources. Upon such approval, the approved method shall use a six (6) sack
minus one-half (1/ 2) inch Portland cement concrete and shall be installed by
positive displacement from the bottom up through a tremmie pipe.
(3-24-22)
04.
Disinfection. All tools, bits, pipe, and other materials to be
inserted in the borehole shall be cleaned and disinfected in accordance with
the Well Construction Standards and permitting requirements of the Idaho Water
Resources Board, referenced in Subsection
002.02 This applies to new well
construction and repair of existing wells. (3-24-22)
05.
Well Completion Report
Required. Upon completion of a well, and prior to its use as a drinking
water source, the following information and data must be submitted by the water
system to the Department. The well completion report must be submitted to the
Department prior to or concurrent with the submittal of the preliminary
engineering report for well house construction/modification. The well
completion report shall bear the imprint of an Idaho licensed professional
engineer's or an Idaho licensed professional geologist's seal that is both
signed and dated by the engineer or geologist: (3-24-22)
a. A copy of all well logs;
(3-24-22)
b. Results of test
pumping, as specified in Subsection
510.06; (3-24-22)
c. As constructed plans showing at least the
following: (3-24-22)
i. Annular seal,
including depth and sealant material used and method of application;
(3-24-22)
ii. Casing perforations,
results of sieve analysis used in designing screens installed in sand or gravel
aquifers, gravel packs; and (3-24-22)
iii. Recommended pump location.
(3-24-22)
d. Other
information as may be specified by the Department. (3-24-22)
e. Sampling results for iron, manganese,
corrosivity, and other secondary contaminants specified by the Department.
Other monitoring requirements are specified in Subsections
510.05.e.i. through
510.05.e.iii. (3-24-22)
i. Community Systems.
Results of analysis for total coliform, inorganic chemical contaminants,
organic chemicals, and radionuclide contaminants set forth in Subsections
050.01,
050.02,
050.05,
100.01,
100.03,
100.04,
100.05, and
100.06, unless analysis is
waived pursuant to Subsection
100.07. (3-24-22)
ii. Nontransient Noncommunity Systems.
Results of analysis for total coliform and inorganic and organic chemical
contaminants listed in Subsections
050.01,
050.02,
100.01,
100.03,
100.04, unless analysis is
waived pursuant to Subsection
100.07. (3-24-22)
iii. Transient Noncommunity Systems. Results
of a total coliform, nitrite, and nitrate analysis listed in Subsections
050.01,
100.01 and
100.03.
(3-24-22)
06.
Test Pumping. Upon completion of a ground water source, test
pumping shall be conducted in accordance with the following procedures to meet
the specified requirements: (3-24-22)
a. The
well shall be test pumped at the desired yield (design capacity) of the well
for at least twenty-four (24) consecutive hours after the drawdown trend has
stabilized, as determined by the supervising engineer or geologist.
Alternatively, the well may be pumped at a rate of one hundred fifty percent
(150%) of the desired yield for at least six (6) continuous hours after the
drawdown trend has stabilized, as determined by the supervising engineer or
geologist. The field pumping equipment must be capable of maintaining a
constant rate of discharge during the test. Discharge water must be piped an
adequate distance to prevent recharge of the well during the test. If the well
fails the test protocol, design of the water system shall be re-evaluated and
submitted to the Department for approval. (3-24-22)
b. Upon completion of well development, the
well shall be tested for sand production. Fifteen (15) minutes after the start
of the test pumping (at or above the design production rate), the sand content
of a new well shall not be more than five (5) parts per million. Sand
production shall be measured by a centrifugal sand sampler or other means
acceptable to the Department. If sand production exceeds five (5) ppm, the well
shall be screened gravel packed, or re-developed. (3-24-22)
c. The following data shall be provided:
(3-24-22)
i. Static water level in the well
prior to test pumping; (3-24-22)
ii. Well yield in gpm and duration of the
pump test, including a discussion of any discrepancy between the desired yield
and the yield observed during the test; (3-24-22)
iii. Water level in the well recorded at
regular intervals during pumping; (3-24-22)
iv. Profile of water level recovery from the
pumping level projected to the original static water level. (3-24-22)
v. Depth at which the test pump was
positioned in the well; (3-24-22)
vi. Test pump capacity and head
characteristics; (3-24-22)
vii.
Sand production data. (3-24-22)
viii. Results of analysis based on the
drawdown and recovery test pertaining to aquifer properties, long term
sustained yield, and boundary conditions affecting drawdown.
(3-24-22)
d. The
Department may allow the use of other pump test protocols that are generally
accepted by engineering firms with specialized experience in well construction,
by the well drilling industry, or as described in national standards (such as
ANSI/AWWA A100-97), as long as the minimum data specified in Subsection
510.06.c. are provided. The
Department welcomes more extensive data about the well, such as step-drawdown
evaluations used in determining well capacity for test pumping purposes, zone
of influence calculations, and any other information that may be of use in
source protection activities or in routine water system operations.
(3-24-22)
e. Where aquifer yield,
sustainability, or water quality are questionable, the Department, at its
discretion, may require additional site specific investigations that could
include test well construction, long-term pumping tests, or other means to
demonstrate that the aquifer yield is sufficient to meet the long-term water
requirements of the project. (3-24-22)
07.
Conversion of Non-Public Water
System Wells for Public Water System Use. Any existing well constructed
for use other than as a public water system source may be considered for use as
a public water system source on a case-by-case basis. The owner of such a well
must demonstrate to the Department's satisfaction that the well site conforms
to the requirements of Subsections
510.01,
510.02, and Section
512, the well is constructed in a
manner that is protective of public health and that both the quantity and
quality of water produced by the well meet public water system standards set
forth in these rules. (3-24-22)
08.
Observation Wells. If observation wells are used and are intended
to remain in service after completion of the water supply well, the observation
wells shall be constructed in accordance with the requirements for permanent
wells and be protected at the upper terminal to preclude entrance of foreign
materials. See Rules of the Idaho Water Resources Board referenced in
Subsection 002.02. (3-24-22)
09.
Well Abandonment. Any water
supply well that will no longer be used must be abandoned by sealing the
borehole carefully to prevent pollution of the ground water, eliminate any
physical hazard, conserve aquifer yield, maintain confined head conditions in
artesian wells, and prevent mixing of waters from different aquifers. The
objective of proper well abandonment procedures is to restore, as far as
possible, the original hydrogeologic conditions. The services of a licensed
well driller are required. Instructions for abandoning various types of wells
may be obtained from the Idaho Department of Water Resources. See Rules of the
Idaho Water Resources Board referenced in Subsection
002.02. (3-24-22)
