DDW-2024-006564

March 14, 2024
Zachary Renstrom, Manager
Washington County Water Conservancy District
Quail Lake Water System
533 East Waterworks Drive
St. George, Utah 84770
Subject:Exception to R309-550-7 Minimum Separation Requirements for Quail Lake to Cottam Transmission Line Replacement, 24-inch water line and Laterals crossing and 8-inch Sewer Line;
System #27094, File #13643
This letter is not Plan Approval for construction.
Dear Zachary. Renstrom:
On March 4, 2024, the Division of Drinking Water (the Division) received your request for an exception to Rule R309-550-7, Separation of Water Mains and Transmission Lines from Sewers
and Other Pollution Sources for the Quail Lake to Cottam Transmission Line. This rule states specifically that where water lines and sewer lines cross, the water main shall be at least
18 inches above the sewer line.
Background Information
Washington County Water Conservancy District (WCWCD) is replacing a transmission line from the Quail Creek Water Treatment Plant (QCWTP) to the Harrisburg area of Hurricane, UT. A 24-inch
diameter CL 350 ductile iron transmission line will replace an existing 10-inch diameter water line.
The pipeline alignment follows easements/right of ways owned by a number different state and
federal entities, including the Bureau of Land Management, UDOT, and Hurricane City. These
easements/right of ways dictated several components during the design of the project. An item of significant impact within the UDOT right of way is a requirement to install the new water
line with a minimum bury depth of 60 inches below finished grade. Typically, water lines in Southern Utah are designed with a minimum bury depth of 36 inches to 42 inches. The existing
easement/right of way that the new pipeline needed to follow is already fairly crowded with other utilities, including the existing water line (which needs to remain in service during
construction of the replacement), an existing sewer line (force and gravity flow sections), power lines, and communications lines. In addition, SR-318 (the road around Quail Creek Reservoir)
needed to remain open during construction. All of these factors provide significant limitations of where the new water line could be installed.
Exception Request
The basis for your request for an exception to R309-550-7(1) is that due to the constraints described above, the replacement water line will have to cross under the sewer in several
locations. These are described below:
Stations 69+00, 131+50, and 189+75: Due to the shallow depth of the existing sewer lines and the minimum 60-inch cover on the new water line per UDOT requirements, the water line will
need to cross underneath the existing sewer line.
These locations will all be a 24-inch diameter water line and will be sleeved with a 36-inch diameter casing, 10 feet on either side of the crossing with a wrap-around rubber seal that
is clamped to the sleeve on each end.
Stations 88+70, 91+35, 92+90, 96+37, 108+76, 111+30, 113+73, 118+50, and 124+56. These are all service connections, pipe drains, and hydrant laterals that will come off the replaced
water line and will need to cross the existing sewer line. The location of the existing sewer line is unknown at this time and when possible, will cross with adequate separation above
the water line. However, if proper separation cannot be maintained or they have to cross underneath, they will also have a larger sleeve pipe encasing them for 10 feet on either side
of the crossing with a wrap-around rubber seal that is clamped to the sleeve on each end.
The existing sewer line is an 8-inch diameter Schedule 80 PVC with cast iron fittings and is believed to be in good condition. No groundwater has been encountered in any of the subsurface
potholing.
On this basis, an exception to R309-550-7(1), Separation of Water Mains and Transmission Lines from Sewers and Other Pollution Sources, is hereby granted for specific locations described
above.This exception may be rescinded at any time if new evidence indicates that the conditions of this exception are no longer being met or a public health risk exists due to this exception.
Please maintain a copy of this letter with your permanent records for future reference.
If you have any questions regarding this exception, please contact J. Paul Wright, P.E., DEQ Southwest District office, at [phone], or me, at [phone].
Sincerely,
Michael Newberry, P.E.
Permitting and Engineering Support Manager
JPW/mrn/mdbcc:Jeremy Roberts, Southwest Utah Public Health Dept., [e-mail] Meyer, P.E., Bush and Gudgell, Inc., rmeyer@bushandgudgellDave Jessop, Washington County
WCD, [e-mail] Renstrom, Washington County WCD, [e-mail]. Paul Wright, P.E., DEQ Southwest District Engineer, [e-mail]
Pwright 27094 13643 WS sep EG