Lateral 7R Pipeline Replacement Project

Lateral 7R Pipeline Replacement Project

The proposed Project would involve the replacement and relocation of an approximately 4.2-mile-long segment of the WWD Lateral 7R, with delivery tie-ins and connections to two District reservoirs at existing pumping plant facilities. The pipeline will be installed across the I-5 transportation corridor and associated California Department of Transportation (Caltrans) right-of-way using jack-and-bore methods. Staging areas will be located onsite and adjacent to proposed pipeline within the Area of Potential Effect (APE). The APE identified for biological and cultural surveys is approximately 50 acres. The Project will replace an approximately 4.2-mile segment of the Lateral 7R, from STA. 109+81.60 to 212+88.30 and STA. 215+00.00 to 333+92.63. The existing mortar-lined steel pipe will be replaced with an equivalent size and class of High-Density Polyethylene (HDPE) pipe. Dimensions of the existing pipe to be replaced are as follows: • 2, 660 linear feet (+-) of 42-inch diameter • 7, 650 linear feet (+-) of 39-inch diameter • 2, 180 linear feet (+-) of36-inch diameter • 6,050 linear feet (+-) of33-inch diameter • 3, 660 linear feet (+-) of30-inch diameter Dimensions of the replacement pipe are as follows: • 13,943 linear feet (+-) of48-inch diameter • 5,038 linear feet (+-) of 42-inch diameter • 3,674 linear feet (+-) of36-inch diameter Pipeline replacement will entail using primarily open cut methods to install the new pipe parallel to the existing pipe. This will allow the existing pipe to remain in service during most of the construction window. While the existing pipeline travels through the landowner's farmable ground, the new alignment will be confined to existing dirt roads. Relocation of the pipeline alignment will require the acquisition of additional easements (four new easements across six Assessor's Parcel Numbers). The new lateral will be constructed to a depth meeting the requirements of the new and existing easements, while minimizing construction costs and avoiding existing utilities including multiple gas and petroleum transmission mains. Where the proposed alignment crosses Tumey Gulch, appropriate ingress and egress will need to be provided before open cut trenching can occur. First, vegetation and debris will be cleared from a 35- to 40-foot-wide corridor centered on the proposed pipeline location. Next, an excavator will be used to remove excess overburden from the trenching route, digging a path 14 to 16 feet wide and approximately 6 feet over the top of the proposed pipeline. The excavator would then be used to dig the trench for the pipe, following which the pipe would be placed (minimum depth of 6 feet below pre-project grade), backfilled, and compacted. Following pipeline installation across Tumey Gulch, the removed overburden will be returned to the trenching route, and the bed and banks of the gulch will be returned to pre-project contours to the maximum extent feasible. Where the proposed pipeline crosses Interstate 5 and the associated Caltrans right-of-way (ROW), jack and bore methods will be used to first install a new 66-inch steel casing under the ROW, following which the new 42-inch HDPE water main (carrier pipe) will be pulled through the casing. In addition to the pipeline replacement, nine delivery tie-ins up to and including the dresser coupling, and eight subline connections including the respective subline valves will be made. Additionally, the new pipeline will be connected into the inlet structure of the existing reservoirs at two separate pumping plants; these are identified as Reservoir 7R-B (Pumping Plant 7R-C) and Reservoir 7R-C (Pumping Plant 7R-D). Since the pipeline being replaced is a Federally owned but operated and maintained by Westlands and since WWD is acquiring new easements on USBR behalf, USBR will need to take action for the modification to the facility and transfer of the easements from WWD to USBR. Following construction, the existing pipe will be abandoned in place and filled with a two-sack cement slurry to prevent collapse in the future as the pipe material degrades.

western unincorporated Fresno County

Fresno

Northern California

Fresno