- ENGINEERING INFO
- CASE STUDIES
When a city is located in the middle of a desert it will take water from anywhere it can find it. So it mattered little when Carlsbad, New Mexico secured rights to nearly seven million gallons per day of water that was over 50 miles away. Local engineering firm, Molzen Corbin, was tasked by the City with designing a transmission pipeline system to convey this water from two existing tanks with two million and three million gallons of storage capacity, respectively.
The new transmission pipeline project, Carlsbad Double Eagle, included two phases as well as the use of some existing pipelines: Phase 1, consisted of 19,410 LF of 24-inch header pipe, 59,190 feet of 16-inch lateral pipe, and five pressure reducing valve stations. The 16-inch pipe from the existing two million gallon storage tank was designed to deliver a flow of 3.46 million gallons per day. The 16-inch pipe from the existing three million gallon tank was designed to deliver a flow of 3.37 million gallons per day. Both 16-inch pipes connected to the single 24-inch header pipe with an overall design capacity of 6.83 million gallons per day.
Molzen Corbin engineers were already familiar with Fusible PVC® pipe, primarily through trenchless installations. During the design phase of the Double Eagle Phase 1 project, the firm identified dozens of required crossings and contacted Underground Solutions to discuss potential ways that Fusible PVC® pipe could help minimize installation costs for constructing the crossings.
Horizontal Directional Drilling (HDD) was considered, but many of the crossings were too short to make HDD a feasible solution given the diameter of the lines. Instead, Molzen Corbin selected jack-and-bore installation at the crossings and specified three acceptable pipe materials for the carrier pipes: bell-and-spigot C905 PVC pipe, ductile iron pipe, and Fusible C-905® pipe. Recognizing that the OD of Fusible C-905® pipe at the fused joint is equivalent to the pipe barrel because there are no bells, Molzen Corbin allowed contractors to downsize the steel casing sizes for the Fusible C-905® carrier pipe option. Molzen Corbin also recognized that without bells there would be no need for casing spacers to avoid point-loading, leading to additional cost reductions.
On bid day, AUI, Inc. won the project using downsized casings with Fusible C-905® carrier pipe in its winning bid. Shane Bender, lead estimator for AUI on the project, said: “There were so many crossings, nearly 50, that the savings realized by downsizing the casing pipe and boring smaller crossings made it a no brainer for us to use Fusible C-905® carrier pipe. Also, many of the crossings were 40 linear feet, the length of one stick of Fusible C-905 pipe, so we didn’t even have to worry about fusion for many of the crossings.”
|Pipeline Details and Project Summary|
|Project:||Carlsbad Double Eagle, Phase 1|
|Length and Size:||3,120 LF 16” DR25 Fusible PVC® 1,710 LF 24” DR25 Fusible PVC®|
|Pressure Test||150 psi for 2 hours|
|Owner:||City of Carlsbad, Luis Camero|
|Engineer:||Molzen Corbin, Ken Muller & Angel Campos|
|Contractor:||AUI, Inc. Shane Bender and Erick Garcia|
|UGSI Contact:||Steve Austin (303) 563-9467 firstname.lastname@example.org|