The Mesa Riverview development in Mesa, Ariz., includes an auto mall, office park, hotel, movie theaters and retail and dining facilities. The construction of a new Home Depot took place during the second phase of the project. When research and planning began for the optimal storm water solution for the site, it was discovered that the soil had a low percolation, or infiltration, rating.
When soil has a poor percolation rating, water cannot enter the ground unimpeded during a rainfall event; it either ponds on the surface or runs off the land. Runoff can carry soil particles and other contaminants to streams and lakes, increase the chance of local flooding of streams and rivers, plus result in accelerated soil erosion. In a hot and dry climate such as that of Arizona, a bad percolation rating may cause storm water to evaporate instead of being returned to the ground or used for irrigation purposes.
Under the guidance of contractor Ricor Inc., Phoenix, and engineer Ryan Taylor of Carter & Burgess, Phoenix, several storm water options were considered for the second phase of the project, including metal culvert pipes. An underground system, though, was selected to manage runoff in the poor percolation conditions.
According to the system design, the chambers would detain storm water and send it to an aquifer. An impervious liner covered the bed underneath the plastic chambers to prevent storm water from infiltrating the ground and to direct it into the aquifer for storage and future use.
Ultimately, 168 CULTEC Recharger 330 chambers were specified for the project, providing 12,480 cu ft of storage. Installed in October 2006, the single-layer system occupied 52,846 sq ft and was installed in one rectangular bed. The chambers are lightweight and require less heavy equipment and labor than alternative options, making for a simpler and more cost-effective installation.
In this particular application, the chambers were also able to go above and beyond their basic storm water recharge function; they worked well together with the aquifer to recreate a natural infiltration process and preserve water as well.
There are many benefits to using a subsurface system, including minimized land disturbance, reduced maintenance costs compared to above-ground systems and design flexibility that allows the chambers to be installed in separate beds or multiple layers.
Specific to this Home Depot development application, subsurface chambers also have exhibited the potential to aid in the natural infiltration process while performing their primary purposes of capturing and recharging storm water runoff.