KE&G Construction Partners with CEMEX on Palominas Flood Protection Project
What began as a job to prevent flooding at an Arizona elementary school, the $1.5 million Palominas Flood Protection and Groundwater Recharge project in Cochise County, became an award-winning environmental project that gained Congressional attention.
"It was designed to recharge the water that was flooding this grammar school," says Larry Saunders, Senior Project Manager for KE&G Construction in Sierra Vista, Arizona.
Cochise County hired KE&G Construction to construct a basin and 42 concrete check dams through which the water flowed back to the San Pedro River while passing through recharge areas. Many people, including the Nature Conservancy, consider the river the Southwest's last free-flowing river. But drought has led the river to run dry at times.
"This is the first project of its kind in the southwest," says Robin Dodson, Territory Manager for CEMEX in Arizona. "Flood prevention is key, but moreover, those waters are now captured and put back into the aquifer. Capturing every drop of water is essential to sustaining life in our region."
The Palominas project was the part of a multiphased larger flood control program in the area through the San Pedro River Recharge Network, comprised of the Walton Foundation, Cochise County, Fort Huachuca, the Nature Conservancy and City of Sierra Vista.
The Nature Conservancy purchased the 285-acre Mansker tract through funding provided by the Wingate Foundation and U.S. Army's Army Compatible Use Buffer (ACUB) Program. That track was used for the project. The ACUB program helps to protect key lands near military bases across the nation that will enhance the mission of Army installations.
The conservancy transferred ownership of the property to Cochise County, for its long-term management of the site, and later the Nature Conservancy and the county brought engineers and scientists together to design the award winning facility. The Walton Family Foundation provided the funds for much of the design, engineering and initial construction of the recharge facilities. Support from the U.S. Agricultural Research Service has also been important in terms of the ongoing hydrologic monitoring needed to quantify the benefits of the project.
JE Fuller Hydrology & Geomorphology of Tempe, Arizona, designed the project.
"It was an incredible concept and was one of the first to use this design," Saunders says. "In Arizona, water is a precious resource."
KE&G Construction worked closely with CEMEX in Sierra Vista, which supplied the concrete, and completed the project within three months, at the end of July 2014, beating the heaviest rains of the summer monsoon season.
"CEMEX geared up to fully accommodate us with concrete," says Saunders, adding that without that daily support from CEMEX, the company would not have completed the project within the desired time frame.
KE&G Construction had worked with CEMEX on projects in the past and had a good relationship. The contractor planned ahead and notified CEMEX early.
"CEMEX partnered with the owner of this project, Cochise County, and our customer, KE&G Construction to optimize the performance of our fleet to meet the three-month schedule prior to monsoons hitting," Dodson explains. "Our Tucson locations supplied additional trucks during those times the schedule required multiple locations on the project be serviced at the same time. Our crews worked as late as needed to get that day's pours completed."
Dodson also credited the entire team with making the project a success, saying, "Sergio Gallego, of KE&G Construction, utilized a lot of keen insight in our approach to what would prove to be some tough terrain, and we could not have had a better partner than KE&G Construction. Karen Riggs and Dennis Donovan, of Cochise County Highways and Flood Plains, and Cyrus Miller, of JE Fuller, were a very special team to work with. Their enthusiasm and dedication to bringing this project to fruition were endless, and it is an honor to have been a part of such an innovative, forward thinking project."
A Challenging Terrain
Grassy slopes surrounded the school and allowed water to flood into the structure. The project sits on a federally protected conservation easement. The sloping terrain and sheet flow presented challenges to construction. Crews moved significant quantities of dirt to contain the water flow.
KE&G Construction began by clearing the site and excavating the sloping site for a 1-acre retention pond to collect the stormwater, dry wells and infiltration trenches. The basin can hold up to 17 million gallons of water. The dry wells and infiltration trenches provide additional storage capacity for the water and reduce the water loss through evaporation. Within the retention pond, KE&G Construction built a large concrete overflow structure with a metering device. The overflow structure required 1,750 yards of concrete and 1,100 tons of crushed rock.
The water from the basin flows into a 120-foot side channel that leads to 13 in-channel recharge basins across the street, between the school and the San Pedro River. Water flows over the top of each of these 4-foot high check dams, gradually making its way to the river or into the ground to replenish the aquifer.
To save time, the company changed the reinforcing to a microfiber mesh. The tiny fibers in the mesh mix with the concrete, spread out and lock with one another to strengthen the concrete. It used 1,160 pounds of the microfiber additive.
KE&G Construction also installed equipment that continually monitors precipitation, the behavior of water flowing through the system and changes to groundwater levels over time. The project serves as a pilot and will be evaluated to see if it should be duplicated in other areas.
The new stormwater control project captured 12-million gallons of rainwater during the 2014 monsoon season and 2.15-million gallons during the 2015 season. Nearly all of the rainwater was captured and recharged into the ground.
The project received a merit award from the Arizona Association of Counties (AAC), an AAC Judge's Merit Award for Innovation of the Year, and the American Public Works Project of the Year in the Environment Category, Less Than $5 Million, at the state level. Most recently, the project placed third in the Infrastructure and Urbanism Category at the XXIV CEMEX Building Awards. Rep. Martha McSally of Arizona read a summary into the Congressional Record in December 2015.
"I am incredibly proud of the teamwork between CEMEX employees and the KE&G crews to get the job done safely, on time and on budget," Dodson says. "We are honored to have been a part of this award-winning, historically significant project."