007.01 The Director
will review plans and specifications for substantial conformance to the
"Recommended Standards for Water Works", 2007 Edition and the requirements of
Title 179 NAC 7. In the event of discrepancy, Title 179 NAC 7 will govern. The
Department will consider approving designs that follow generally accepted
engineering guidelines and standards published by national engineering
societies, federal environmental agencies, public health boards, engineering
textbooks used by accredited university engineering programs, documented
successful installations or successful pilot/full scale testing.
007.02 Chemical Feed Systems
All chemical feeders must have primary and secondary
interconnect control devices to prevent overfeeding. Where applicable, chemical
feeders must be electrically interconnected with the well or service pump and
must also be provided with secondary control devices as a means of reducing the
possibility of overfeed. An exception to this may be made for systems that have
warning devices and are staffed 24 hours a day, 7 days a week.
007.03 Wells/Groundwater Source(s)
1. Every well, infiltration line or spring
serving or intended to provide water for a public water system, to the greatest
extent possible, shall be located, constructed, or modified in such a manner
that neither underground nor surface contamination by any biological, chemical
or radioactive substance or by the physical property of any substance from any
cesspool, privy, septic tank, sub-surface tile system, sewer, drain, pit below
ground surface, abandoned or decommissioned well, animal or avian wastes, or
any other possible source of pollution can adversely affect such water supply.
The minimum recommended horizontal distances in feet separating the well,
infiltration gallery or spring from potential sources of contamination are as
described in the following table. The Department will consider location, of
wells and springs at closer proximity than the minimum distances below.
Approval for such location may be given when circumstances require such
location, but only if, in the opinion of the Director, the engineer
demonstrates that such location will not constitute a pollution hazard to the
supply. The examples are not meant to be all inclusive. When locating a ground
water source, the owner of a public water system shall consider all potential
sources of contamination and anything which may affect the ability of the
source to produce an adequate supply of safe water on a continuous basis. When
surface runoff or underground movement from potential sources of contamination
may adversely affect the quality of water from such supplies, the distance
separating these potential sources of contamination and the well, infiltration
gallery, or spring should be greater than that listed in the following
schedule.
|
CATEGORY
|
DISTANCE Feet
|
| Water Well |
1,000 |
| Sewage Lagoon |
1,000 |
| Land application of municipal/industrial waste
material |
1,000 |
| Feedlot or Feedlot Runoff |
1,000 |
| Underground disposal system (septic system, cesspool,
etc.) |
500 |
| Corral |
500 |
| Pit Toilet/Vault Toilet |
500 |
| Wastewater Holding Tanks |
500 |
| Sanitary Landfill/Dump |
500 |
| Chemical or Petroleum Product Storage |
500 |
| Sewage Treatment Plant |
500 |
| Sewage Wet Well |
500 |
| Sanitary Sewer Connection |
100 |
| Sanitary Sewer Manhole |
100 |
| Sanitary Sewer Line |
50 |
NOTE: If the distance requirements in 179 NAC 13
Attachment 2 are not met, the well is subject to testing to determine if it is
ground water under the direct influence of surface water. If a well meets that
definition, it is treated as a surface water source subject to all the
requirements of the rules regarding surface water.
2. A test hole is required for all proposed
well sites or the engineer must provide similar information that would have
been provided by the test hole.
3.
The annular space must be grouted (cement based grout) to a minimum depth of 10
feet below the ground surface. If a pitless unit is to be installed, the upper
limit of the cement based grout must be one foot below the field connection of
the adapter. Crushed or chip bentonite must be installed from the top of the
designed gravel pack to the base of the cement based grout. In order to
accomplish this, the annular space must be 4 to 12 inches larger than the
nominal casing size. Pouring into a dry annular space is preferred. Placement
of the bentonite into the annular space must be done in a manner which ensures
that bridging does not occur. Prior to using this material, it must be sieved
over a 1/4 inch mesh screen to remove fines which may have accumulated in the
bag during shipment. Any alternate annular space grouting/sealing proposed must
be justified by the engineer with supporting documents.
4. The following information must be
submitted with the plans and specifications, addenda thereto, or prior to
construction:
a. Test hole driller's logs and
reports or similar information.
b.
All sieve analysis and calculations used in gravel pack and screen design. This
information must be submitted prior to the placement of the screen and gravel
pack.
5. The well casing
must be at least two nominal sizes larger than the bowl size of the
pump.
6. Well casing lengths must
be joined by a watertight method appropriate to the material used so that the
resulting joint will have the same structural integrity as the casing
itself.
7. Cement-based grout must
be placed by tremie pouring. The tremie pipe must be kept full continuously
from the start to finish of the grouting procedure, with the discharge end of
the tremie pipe being continuously submerged just below the surface of the
grout until the zone to be grouted is completely filled.
8. The filter pack grain size must be
determined by taking the 70% retained grain size of the finest formation to be
filtered and multiplying it by 4, 5, or 6. This is the 70% retained grain size
of the filter material to be used. The uniformity coefficient (the size of
sieve that retains 40% of the sample divided by the size that retains 90%) must
not be greater than 2.5. The gradation of the filter material must form a
smooth and gradual size distribution curve when plotted. The screen aperture
openings must be of such size as to retain between 85% and 100% of the filter
material. The total open area of the screen must be such that the entrance
velocity of water at the design condition does not exceed 0.1 feet per second
(fps) with 50% of the screen open area blocked off.
9. The length of filter pack must extend a
distance of 2-1 /2 times the maximum diameter of the well above the screen and
below the screen, unless terminating in bedrock or clay.
10. The filter pack must be placed with a
tremie pipe by washing or pumping the filter material in with water as a
slurry.
11. The sand content must
be determined from averaging the results of at least 5 samples collected over
the course of the constant rate pump testing. The average of the sand content
from these test results must not exceed two parts per million (ppm).
