Tarrant Regional Water District Receives ISI Envision Silver Award
September 22, 2014
The Tarrant Regional Water District (TRWD), of North Central Texas has earned the Envision sustainable infrastructure rating system’s Silver award for their Line J, Section 1 Pipeline project. The pipeline was designed by Freese and Nichols, Inc., a charter member of ISI.
The Envision Silver award-winning project is a two mile, 108-inch diameter pipeline delivering water from the Kennedale Balancing Reservoir directly to the Arlington Outlet, dedicating a significant amount of water demand from the existing pipelines, and allowing the District to meet future demands at the Rolling Hills Water Treatment line, and locations further west. The water delivered to the Arlington Outlet can be either piped through the existing discharge facility, or go through to the new hydroelectric facility.
“The TRWD pipeline project received the Envision Silver award because of its areas of high achievement in the quality of life for communities in the area that have experienced drought conditions, as well as the stimulation of sustainable growth and development due to increased water demands in one of the fastest growing communities in the U.S.,” said ISI President and CEO, William Bertera. “The TRWD has also provided effective leadership and commitment to begin and implement sustainable practices, and significant efforts have been undertaken by the District to put their commitment into action,” Bertera said.
Shelly Hattan, the Line J Project Engineer, said “TRWD is very proud of our achievement of infrastructure sustainability as recognized by the ISI Envision Silver award. This pipeline provides increased system reliability to area customers, and is designed to accommodate future water supplies in the area. The evaluation of this project by the industry’s leading sustainability rating system shows that TRWD is expanding our continued commitment to sustainable practices.”
The Envision system measures sustainability in infrastructure projects through the measurement of five categories: Quality of Life (QL), Leadership (LD), Natural World (NW), Resource Allocation (RA), and Climate and Risk (CR) that contribute to overall credits for the positive social, economic, and environmental impacts in a community in the planning, design and construction of infrastructure projects. The highest-rated project categories that the TRWD Pipeline scored using the Envision rating system included:
Quality of Life (QL): The TRWD Pipeline project scored highly in the improvement of area communities’ quality of life. Water demands in Tarrant County are expected to double in the next 50 years, and area lakes have not been able to meet demands, leading to TRWD’s extensive water transmission system. The project improves the net quality of life for many of the communities served by TRWD by increasing their ability to transfer raw water to 1.9 million users.
It also stimulates sustainable growth and development through increased water availability, which increases the community attractiveness to new business and residents. By adding Line J, the efficiency and reliability of TRWD’s water transmission system increases while deferring the need for new water supplies and for more pipelines and pump stations. TRWD’s strategic water plans and operations align with the anticipated economic and development growth of TRWD’s service area.
Leadership (LD): TRWD began implementing sustainable practices prior to the project, and the evaluation and implementation of sustainable practices had been a priority since the beginning of the pipeline project. A Project Management Plan was prepared at the beginning of the project to establish goals, procedures, communication, controls, etc. The consultant team was led by Alan Hutson, P.E., ENV SP, for Freese and Nichols, and sustainability guidance was provided by Elizabeth Blackwelder, P.E., ENV SP, also from Freese and Nichols, which has 26 credentialed sustainability professionals.
A Contractor Manager at Risk (CMAR) was brought in early on to help manage changing conditions, critical schedule, and experimental features of the project. In addition, two specific sustainability tasks were included in the project scope to evaluate complex design alternatives and enhance sustainable management of the project. The team met regularly to assess progress made, convey new data, identify issues, and discuss solutions.
Leadership in this context involves fostering collaboration and teamwork. Significant collaborative effort went into evaluating the use of trench excavated material for pipe embedment through the development of native CLSM. Having a CMAR in the project automatically incorporates a benefit/risk sharing component. For example, the CMAR was required to review and provide evaluation regarding construction cost throughout different phases of the project, identify potential bidders, create interest in the project amongst contractors and manufacturers, etc.
In implementing a sustainable design, the team applied the Envision® sustainable infrastructure rating system. They also involved civil engineering graduate students at the University of Texas at Arlington, who evaluated the use of native soils to produce controlled low-strength material (CLSM). Collaboration and design integration with the students produced exceptional social benefits.
Natural World (NW): To maintain wetland and surface water functions, hydraulic studies and geomorphology studies were performed at Village Creek to complete the pipeline crossing under the creek and the surface restoration design. Two ecosystem functions are maintained by the Line J pipeline. Hydrologic connections are maintained and enhanced by restoring all contours to existing pre-construction contours at creek crossings. Sediment transport functions are maintained by removing materials deposited in the bottom of the creeks which impede the natural flow of the water carrying sediment.
Also rated by the ISI Envision system were the Resource Allocation and Climate and Risk categories of the TRWD Pipeline project, along with the three previous categories. Highlights from these categories helped the project win with the Envision Silver award.
Resource Allocation (RA): The design of the Line J Pipeline incorporates several initiatives to reduce excavated materials taken off site. The excavated soils will be used as: pipe embedment, trench backfill, borrow material to grade properties adjacent to the pipeline, and Pipe Embedment.
The credit was exceeded by developing a method to design, field produce, and field install an embedment material produced with low quality trench excavated soils. This methodology is new to Texas.
Climate and Risk (CR): TRWD has worked towards addressing raising water demand in a responsible way for many years. To the District, this means operating safely, minimizing the adverse impact on the environment, building infrastructure as the service area needs it, and building trust with the customer communities. Their infrastructure system, which Line J is part of, is designed, operated, and maintained to be flexible and resilient to changing climate and social conditions.