Integrated Pipeline Project (IPL), Section 15-1 – Tarrant Regional Water District
The Integrated Pipeline (IPL) Program consists of more than 150-miles of raw water pipeline to connect several North Texas reservoirs in the Tarrant Regional Water District (TRWD) and Dallas Water Utilities (DWU) systems. The program represents a large scale collaboration between the two agencies in an effort to realize significant long-term construction and operational savings for constituents.
Lockwood, Andrews & Newnam, Inc. (LAN) was selected as pipeline design engineer for Section 15-1 of the greater program, which includes more than 15-miles of 108-inch diameter raw water pipeline. LAN provided preliminary design, final design, and construction phase services for the more than $90 million project, which was the first component of the overall IPL program that went to construction. Design included consideration for both steel and concrete pipe (competitively bid) and both flowable fill and traditional granular bedding as part of efforts to promote competition and maximize value.
Section 15-1 included several notable design challenges, including short tunnel sections at large diameter high pressure petroleum pipeline crossings, TxDOT crossings and a Union Pacific Railroad crossing. In addition, Section 15-1 includes the crossing of TRWD’s 90-inch diameter Richland-Chambers Pipeline, which required design of a pressure reducing interconnect with maximum flexibility for future parallel installations.
On completion of design, a bid was accepted and awarded for approximately $93 million dollars, which was more than $30 million below the original construction budget.
At a glance
1,540 LF of 90-inch diameter pipeline was relocated in less than 45 days
Uncoated, cement mortar lined steel pipe was used for the new installation
The depth of cover in some areas of the lowering exceeded 25-feet
No more than 45-days was permitted for construction in order to maintain contracted raw water service
The pipe material was pre-purchased by the Owner to minimize the risk for delays in delivery
The project was bid and constructed under a Construction Manager At Risk (CMAR) contract
By encasing steel pipe in concrete, an alkaline environment similar to the existing prestressed concrete cylinder pipeline was maintained
Construction cost was reduced in part by negotiating an alternate access point requiring less site work
The pressure reducing interconnection at the Richland-Chambers pipeline crossing was architecturally designed to mimic other above ground barns/structures in the area to blend with the landscape
Design efforts included proactive stakeholder engagement with local officials, including Navarro County, the Navarro County Electrical Cooperative, and two local water supply corporations
The preliminary design included a detailed evaluation of likely construction access routes, including consideration of load ratings for bridges needed to deliver goods
Development of the Richland-Chambers interconnection site required design of improvements to an unpaved county road to ensure all-weather access could be provided
The awarded contractor elected to utilize three pipe laying crews during construction, cutting construction from a budgeted 24 months to approximately 15
Tarrant Regional Water District