HERRIMAN — New construction may be disappearing from many west-side cities in Salt Lake County, but here, where a newly announced, billion-dollar development is waiting on the horizon, the situation is drastically different.

The Sorenson Group announced plans this week to build a bonanza of development in Herriman's soon-to-be Towne Center project — with a new City Hall, school, county recreation center, county library and courthouse at its core. All totaled, the project — which should begin within 90 days and finish its phases in 10 years — will occupy more than 375 acres in the heart of Herriman.

"Herriman is a very vibrant, growing community in the county," said James Lee Sorenson, CEO of The Sorenson Group. "We've developed a great relationship with Herriman where there is mutual trust and respect. We work together and we understand their needs and goals. They understand some of the challenges and needs that we have."

The Sorenson Group, which developed the Rosecrest area of Herriman, donated 27 acres where Herriman's new City Hall and the newly named J.L. Sorenson Recreation Center will sit in coming years. The development company also donated land to Salt Lake County for a library.

In exchange for donating the land to Herriman, The Sorenson Group will receive allowances to build the residential/retail portion of their project at a higher density.

An estimated 2,000 housing units will be completed as part of the project, including condominiums, townhouses and single-family houses. Some of the units will be completed early next year.

"One of the things that has made Herriman as successful as it has been, I believe, is our perspective of viewing development from a corporate, municipal partnership," said Mayor Lynn Crane. "We have certainly enjoyed that kind of relationship with Rosecrest from the beginning, and they have a wonderful presence in our community."

Construction on the Sorenson Recreation Center should begin by the spring of 2009, to be completed in 2010. The southwest regional project stalled for nine months because the county's original site conflicted with Utah Department of Transportation plans to build the Mountain View Corridor through the area.

Construction on the library should begin next year, said Salt Lake County Mayor Peter Corroon.

"This project really is a recognition of the growth that is taking place in the southwest portion of Salt Lake County," Corroon said. "The growth has happened quickly, so I think we've recognized that growth and are trying to meet that need as quickly as possible."