The New San Antonio River Walk

Twice as long, twice as lush, take the river taxi.

August 11, 2010

In April 2007, Zachry Construction Corporation was awarded a $49.8-million contract to handle all construction in the 1.5-mile-long Urban Segment of the San Antonio Museum Reach. This is part of a larger $216.6-million, 13-mile long San Antonio River Improvements Project being funded by the city of San Antonio, Bexar County and private donations.

Below: Architect’s conception of the Roy Smith Bridge across the San Antonio River illustrates how the River Walk landscaping
will appear upon completion. Rendering courtesy of CFZ Group LLC.

The project will stabilize the river channel, extend navigation by river barge through the addition of a lock and dam, create access along a linear park that links major cultural institutions and commercial centers, and add new landscaping, pocket parks, lighting, and signage.

When construction of the 1.5-mile-long Urban Segment is complete in May 2009, the new River Walk will be double its current length, the river channel will be stabilized, and river barges will be able to navigate the river via a lock and dam. Additionally the project will create a linear park with access to museums and businesses.

Environmental Restoration

As part of the environmental restoration, Zachry Construction is relocating the river, which had been straightened in the 1920s, by restoring the original meandering path of the riverbed. Zachry has split the job into 2,200-foot sections, beginning at Lexington Avenue, to avoid having to dewater too much of the river at one time. In each phase, the area is cleared, dewatered, excavation work is done for bulkheads and retaining walls, and then storm drains, electrical, irrigation systems, sidewalks, and viewing structures are installed. Each 2,200-foot phase of the project is expected to take eight to nine months.

The river area previously consisted of pools up to 20 feet wide and 3 feet deep, with most of the river’s flow being diverted through the San Antonio River Tunnel. The river is now being widened to between 30 feet and 40 feet and will be approximately 4 feet deep, with any excess water pumped into the existing tunnel. 

Standard excavators and backhoes are being used to widen and deepen the river, with the soil being brought to the top and drained, then removed on all-wheel-drive Caterpillar articulated trucks, finally reloaded to highway trucks and transferred to waste areas. 

To keep areas dewatered, standard sumps are being used to send water into the tunnel or divert it downstream. The San Antonio River Tunnel makes controlling excess water easier than some channel jobs, although there was a washout of the riverbed in August 2007 when excess rains caused the flow to increase from 20 CFS to 250 CFS. Complete removal of water is not possible, so Zachry Construction crews have to work around some water in the riverbed, and water is regularly pumped out after any rainfall.

A turning basin and a lock and dam will be constructed to provide an 8-inch lift for barges. The lock and dam require 80 feet of channel. For each bulkhead and retaining wall, Craig Olden, Inc. is installing soil nailing on the slope while the footings, anchor bolts and walls are being constructed.

Landscaping

ISS Grounds Control is installing the irrigation system for the urban segment and will begin landscaping in late May 2008. Soil in and along the riverbed is being stabilized with Geogrid and 18 inches of black dirt. ISS Grounds Control crews trench and install the lines and sprinklers for the irrigation system, then the soil is covered with an erosion blanket. Irrigation will be provided by river water collected at Grayson Street via a two-phase pump which supplies a 6-inch-diameter main irrigation pipe. There are six controllers over the length of the irrigation system, which has 32,000 linear feet of pipe over a one-mile distance. Linear lines cross the river six times in the one-mile span.

Chris Pais of ISS Grounds Control says, “It’s not often we get to work with other subcontractors. Usually landscapers are the last people called in on a job, but here we’re working with Zachry crews, plus electrical and utility and concrete crews. We’re on a tight schedule, but it’s very well coordinated with other contractors. The only obstacle is an occasional difficulty with rain, which can cause rapid water accumulation, so we can’t leave any equipment in the river bed area.”

When ISS Grounds Control begins the landscape phase this spring, trees ranging from 2-inch caliper to 8-inch caliper will be planted to give the appearance of a natural wooded area. Native trees and vegetation will be reintroduced along the river’s edge, including oak, walnut, pecan, redbud, wild olive, buttonbush, Texas bluebonnets, and scarlet sage. Certain existing trees are also marked for preservation. Some nut and fruit trees are to be added to attract wildlife.

Chris Pais of ISS Grounds Control says, “We take a lot of pride in this project. Almost everyone working on it grew up right here in San Antonio and everyone wants to be a part of it.”
Tropical Contracting has had the maintenance contract for sidewalks in the area for years, and is now building 3 miles of new and improved hardscape for the Urban Segment. In this area, the new sidewalks vary in width, with 5-foot, 6-foot, and 8-foot widths being employed, as well as the construction of several sets of stairs. The sidewalks and stairs are a mix of both concrete and natural rock, with Tropical doing all of the concrete walks using 5,000 cubic yards of concrete provided by Alamo Concrete and 300 tons of rebar provided by L&M Steel. Rudy Krisch Construction Company is supplying and installing the rock for the natural finish, which is a 3-inch stone veneer.

Five water features – pools and waterfalls – will be built by Greenscape Pump Services along the new section of River Walk. One will be an overhanging grotto with a waterfall into the river that people can walk under. Each of the water features will use non-potable water from the river.

On-site Surprises

Prior to dewatering of each segment, the San Antonio River Authority is capturing fish for release downstream from the job site. To collect the fish, the River Authority isolates a section of existing pools, a dam is constructed on each end, then the water is pumped down and they net as many fish as they can for relocation. The method works, although herons do congregate in the isolated pools for a fresh fish banquet as the water is pumped down.

Some of the old bridges, which were built in the 1940s, are also being modified because as the water level is lowered, the column hooks and build shafts become exposed. For aesthetic reasons, Zachry is encasing the columns with a bumper, which also helps to reinforce the columns and footings.

Zachry’s excavations also recently uncovered what archaeologists believe to be a dam built in the 1860s for a gristmill. The dam is being saved with the assistance of a full-time archaeologist on the site.

John Walsh, Zachry’s project manager, says, “This is the first job I’ve ever been on where I didn’t get cussed at. There’s a lot of community support and a great deal of public enthusiasm about the project, and we regularly have a lot of people from the community who come to the job site to ask questions and observe the progression of the job.”

www.fedbizopps.govand typing “mission reach ecosystem restoration” in the Quick Search box.


The U.S. Army Corps of Engineers is currently accepting bids for other phases of the San Antonio River Improvements Project Mission Reach Ecosystem Restoration and Recreation Project. Interested contractors may obtain further information on bids by going to

         
 

Comments on: "The New San Antonio River Walk"