Project Legacy Parkway, Salt Lake City Civil engineers Carter & Burgess H.W. Lochner Horrocks Engineers Product application Use of durable materials for highway construction, such as HDPE stormwater pipe, helps minimize intrusion into environmentally sensitive areas.

Highway incorporates design elements, mitigation efforts, and stormwater drainage features to minimize environmental impact.

The Legacy Parkway, a new 14-mile, four-lane highway that opened to traffic on Sept. 13, 2008, provides an alternate road between Salt Lake City and Farmington, Utah. The highway was designed to alleviate congestion in one of Utah’s most heavily traveled corridors, previously served mainly by I-15. On its first weekday of operation—Monday, Sept. 15—the Utah Department of Transportation (UDOT) reported that the Legacy Parkway carried, on average, 26 percent of the I-15 corridor’s traffic (www.dot.state.ut.us/legacy). During the evening peak travel period that day it carried about 44 percent of the corridor’s traffic.

"The goal of the Legacy Parkway is to provide a single, continuous, alternate north-south route through the North Corridor," explained Todd Jensen, Legacy Parkway project director for UDOT. "This new route is essential to reduce traffic congestion and increase safety."

The need for the Legacy Parkway is based on a projected increase in vehicle traffic. Population along the Wasatch Front in the counties of Salt Lake, Davis, and Weber, is forecast to increase by approximately 60 percent by 2020.

However, the project generated a high level of environmental concern because the Legacy Parkway is close to the Great Salt Lake and near the Farmington Bay Waterfowl Management area, about 10 miles north of Salt Lake City. The Great Salt Lake is recognized as an international flyway for migratory birds. The parkway runs along marshlands and the Legacy Nature Preserve, which is home to migrating birds and ducks. The Preserve is a 2,200-plus acre area on the southeastern shore of the Great Salt Lake that was established as environmental mitigation for the Legacy Parkway Project.

The Legacy Parkway stormwater drainage system incorporates approximately 10 miles of HDPE pipe of various diameters. (Photo: UDOT)

The impact of excavation, building, construction traffic, and materials were important considerations in this environmentally sensitive area. Construction crews are required to learn about environmental standards and pass a test before performing work on the project. Minimum intrusion into the sensitive areas and durability of materials were goals of the design team and contractors.

During the course of the project’s development, there were many adaptations and changes from the original layout design and even the bidding process. The original Environmental Impact Statement (EIS) was started in 1997 with a projected project completion date before the 2002 Olympic Games in Salt Lake City. Although construction had started in January 2001, work was restricted by a court injunction in November because of environmental concerns.

The Utahans for Better Transportation and the Sierra Club had filed suit listing 46 items of concern. The court favored UDOT in 41 of the issues; the five outstanding issues were related to the right-of-way width, wildlife, sequencing, Denver and Rio Grande railroad alignment, and integration of mass transit with the highway. UDOT was required to perform a Supplemental Environmental Impact Statement (SEIS) to address these outstanding issues.

HDR provided a variety of services to the Utah Department of Transportation for Legacy Parkway, including an EIS, program management, design oversight, and construction management support. The area HDR evaluated in the EIS comprised a 2,000-foot-wide corridor, crossing rapidly developing lands bounded by the Great Salt Lake on the west and the Wasatch Mountains on the east. Interspersed throughout this corridor are many significant environmental and community resources including prime wetlands inhabited by nesting eagles, peregrine falcons, and migratory birds, as well as farmlands that had been home to families for more than six generations. Developing transportation options that minimized the impact to these resources required the talents of a multi-disciplined team of engineers and scientists. More than 15 types of engineers and 30 classifications of scientists were involved.

During the SEIS process, UDOT chose to meet with the plaintiffs and structure a settlement agreement that required legislative and governor approval. UDOT, the Sierra Club, and Utahans for Better Transportation signed an agreement in November 2005. In addition, the legislature mandated the construction schedule. The agreement included the following provisions:

• 125 aces of additional nature preserve;
• 55 mph speed limit;
• prohibition of trucks with five or more axles or weighing more than 80,000 pounds (except for emergencies);
• trail systems and neighborhood trailheads;
• quiet pavement to reduce the noise; and
• funding of a $2.5 million study to assess the possibility of bus rapid transit and light rail.

The entire Legacy Parkway project comprises 10 neighborhood trail heads; created and protected wetlands in the median; user-friendly and visually pleasing raised pedestrian crossings; native walk pedestrian trails; a nature preserve consisting of more than 2,200 acres, of which more than 700 acres are wetlands; size limitations for trucks; and reduced speeds. The $685 million project is 100-percent state funded through the Centennial Highway Funding program.

Special aspects contributed to some unique design concepts, such as independent horizontal and vertical alignments to minimize the impact on the wetlands and visual impact to the neighborhoods. This use was approved by the U.S. Army Corps of Engineers and the Federal Highway Administration. UDOT chose to raise the pavement section elevation to 4,217 feet, 5 feet higher than the floodwater elevation of 4,212 feet, which was reached in 1983. Additionally, throughout the project, multiple pipe sections equalize the flow of Great Salt Lake floodwaters.

UDOT Legacy Parkway Director Todd Jensen surveys installation of the stormwater drainage system using HDPE pipe. (Photo: UDOT)

Another change to the Legacy project was the bid-letting process. The project originally was a design-build project, which was partially terminated because of the court decision requiring an SEIS. After the SEIS was completed and the settlement agreement was signed, the project was contracted as three design-bid-build projects to encourage industry competition and because the parkway concept was a rather new design concept within the United States.

UDOT conducted research to find existing parkways for comparison but found little information. The closest concept was the George Washington Parkway in the District of Columbia. Because of this concern, UDOT retained design ownership and proceeded with the traditional design-bid-build process. UDOT believed that this process would best incorporate citizen concerns and the best design practices for this concept.

The project was broken into three segments:

Segment 1—2200 North and I-215 to just north of 500 South in Bountiful;

Segment 2—north of 500 South in Bountiful to south of Glovers Lane in Farmington; and

Segment 3—Glovers Lane to the I-15/US-89 interchange.

Construction costs are approximately $90 to $100 million for each segment. UDOT chose the following contractors and design firms:

Segment 1—A&W Construction (Ames and Wadsworth Brothers) with Carter & Burgess as the designer;

Segment 2—Ames Construction with H.W. Lochner as the designer; and

Segment 3—Clyde and Geneva with Horrocks Engineers as the designer.


The teams were allowed 10 months for design, with construction starting December 2006 and obtaining substantial completion by September 2008.

Handling stormwater
Contractors selected high-density polyethylene (HDPE) pipe for all three project segments because of the economics and ease of installation. HDPE pipe is structurally sound, cost competitive, abrasion and corrosion resistant, long lasting, and less intrusive to the environment. The Legacy Parkway project uses more than 56,000 feet of Advanced Drainage System (ADS) HDPE pipe and 400 feet of Hancor HDPE pipe for its stormwater drainage system.

"HDPE was the pipe of choice because it stands up to corrosive environments like the high levels of salt and minerals naturally found in this area near the Great Salt Lake," said Larry Listello, Hancor sales representative for Utah. "The overriding concern was protecting the environment by using pipe that would last the longest time possible and would not have to be dug up and replaced in just a few years because the environment ate away at it."

The parkway contains more than 10 miles of various sizes of HDPE pipe ranging from 18 to 60 inches in diameter. Most of the pipe is from ADS, made at a nearby plant. The project also called for a run of 54-inch-diameter pipe to meet the design flow rate. Hancor’s 54-inch-diameter BLUE SEAL HDPE pipe was the exact diameter needed to carry the design flow and maintain appropriate cover without changing the road profile.

Watertight products were specified and selected from both manufacturers. ADS N-12 and Hancor BLUE SEAL pipe have an integral bell and spigot system and have been widely used in gravity flow storm sewer systems. They also fit the U.S. Environmental Protection Agency’s Phase II best management practices for long-term service reliability.

With a corrugated exterior and smooth interior, the HDPE pipe provides both strength and optimum hydraulic capacity. Because of its light weight, pipe sections can be easily handled with minimal equipment by one- or two-person crews, providing a favorable alternative to the much heavier and shorter length sections of concrete pipe. While an 8-foot section of reinforced concrete pipe can weigh a few thousand pounds, a section of HDPE pipe of the same diameter will weigh just a few hundred pounds. In addition, HDPE pipe’s nominal 20-foot lay lengths reduce the number of joints, which saves labor and installation time.


Tori L Durliat is director of marketing for Advanced Drainage Systems, Inc. She can be contacted at tori.durliat@ads-pipe.com