The bid for what will end up being the last interchange built on the six-mile 120 Bypass is before the Manteca City Council for approval on Tuesday.

DeSilva Gates Construction submitted the lowest “responsive and responsible” bid of $23,387,387 to build the McKinley Avenue interchange with the 120 Bypass.

When completed there will be five interchanges with a mile between each — Yosemite Avenue in Lathrop as well as McKinley Avenue, Airport Way, Union Road and Main Street in Manteca. They are all bookended by the interchange with Interstate 5 on the west and the interchange with Highway 99 on the east.

Work is likely to start later this summer.

That means there will be three major interchange projects underway within a five-mile stretch. Caltrans is targeted to go to bid later this year or in early 2023 for the first phase of the $154 million revamp of the 120 Bypass/Highway 99 interchange.

The first phase of the project will add a second transition lane to southbound Highway 99 from the 120 Bypass interchange. It also involves tearing down the existing Austin Road interchange on Highway 99 to accommodate additional freeway lanes.

The replacement overpass for Austin Road will be four lanes. It will also span the railroad tracks requiring connecting street work from Austin Road to Atherton Drive as well as a new crossing alignment for Woodward Avenue to reach Moffat Boulevard.

The McKinley project will create a partial cloverleaf designed to eventually be expanded to a full cloverleaf as traffic warrants.

The big price cost for the project is the need to import dirt to construct the ramps on as the freeway at that point was elevated using dirt to elevate it out of the flood zone of the San Joaquin River.

McKinley Avenue as it passes under the freeway will be widened to four lanes.

The interchange will have metered ramps for congestion control.

It will take pressure off of the Airport Way interchange to provide access to more than 3,000 homes in four different developments that have started or are about to do so in southwest Manteca. Without it, all of the traffic generated from the new homes  would have to funnel through the Airport Way interchange.

It also will provide access to future business parks in Lathrop approved northwest west of the interchange as well as the family entertainment zone anchored by the 500-room Great Wolf indoor waterpark resort and the Big League Dreams sports complex that Manteca is pursuing on city-owned land..

The option that Great Wolf has to buy city land to possibly build an additional 200 rooms can’t be exercised until construction starts on the McKinley Avenue interchange.

The project is being funded with $12.3 million in state funds, $7 million in Measure K funds collected from the countywide half cent road and transportation tax, and well as $8 million the city has collected in growth fees for major road endeavors.

The council meets Tuesday at 7 p.m. at the Civic Center, 1001 W. Center St.

To contact Dennis Wyatt, email dwyatt@mantecabulletin.com