Storm Water basin aids in managing water levels in California casino project
Despite its semi-arid climate, characterized by mild, moist winters and hot, dry summers, the area in and around Fresno, California, has experienced numerous flood events. From elevations reaching 5,000 feet in the Sierra-Nevada mountain range, streams carry runoff from a 175-square-mile area flow onto the valley floor, where they periodically inundate farmland and urban development, including downtown Fresno. Storm flows have caused local streams and canals to overflow an average of once every four years since 1953.
In the early 1950s, a group of citizens banded together to find solutions to the area’s increasing storm water management problems. Their efforts culminated in the Fresno Metropolitan Flood Control District, created in 1956 to plan and construct flood control infrastructure throughout the Fresno/Clovis metropolitan area.
The district is mandated to control storm water within the Fresno County Stream Group, a rural and urban foothills watershed of approximately 400 square miles. The Redbank-Fancher Creeks Flood Control Project is a cooperative effort by the Army Corps of Engineers, the State of California and the Fresno Metropolitan Flood Control District, to control storm flows through a system of dams, reservoirs, channels and streams.
The Fancher Creek and Big Dry Creek reservoirs were constructed in the early 1990s to alleviate flooding. The nature of Fresno’s climate and geography demands that any new construction must include a plan for the capture and management of storm water.
A Case in Point
The Table Mountain Casino & Hotel Project, constructed last year in the foothills outside of Fresno. Located in Fresno County, the Table Mountain Casino is owned and operated by the Table Mountain Rancheria of California. The tribe is made up of people from the Monache tribe and Chukchansi band of Yokuts.
The new casino nearly doubled the amount of gaming floor space to 110,000 square feet and added a 151-room hotel with resort-like amenities. The project, sitting on 45 acres next to Millerton Lake, also includes an event center and bingo hall. The 14-floor hotel has sweeping views of the San Joaquin Valley.
Teichert Construction (Sacramento, California) was contracted to install the storm water system, designed by NV5 Engineering, out of its Fresno office.
Almost immediately, Teichert encountered a problem: the pre-cast concrete pipes originally specified by the engineer were not suitable for the job, which required the installation of pipes and basins across several different elevations. The issue had to do with the pre-cast concrete basins, which cannot be easily adjusted to the various grades in a drainage field with multiple levels.
The solution was the Nyloplast Water Control Structure by Advanced Drainage Systems Inc., a storm water basin that provides an effective way to manage water levels in a variety of applications.
A key feature is the ability for the installer to make changes “on the fly.” For example, if the inlet is sitting above grade, the PVC riser can easily be cut flush to grade. Or if the riser ends up sitting below grade, the inlet can be raised up using extension pieces. This project used 58 units.
“We chose the pipe products and basins for the ease of install and also the quick availability of product. The different grade levels on the project required a product that could be versatile and allow for changes to be made quickly and easily. It was a no brainer to flip from pre-cast concrete,” said Bart Krieger, Teichert Project Manager. “It handles well, and you have the flexibility to make adjustments, that was the biggest thing.”
The unit combines ductile iron grates with a rugged, heavy-duty PVC structure. The product line includes inline drains, drain basins, curb inlet structures, road and highway structures and drop-in grates, which can be used for any underground storm drain pipe system. ADS has developed an online program for determining the best drain basin for a particular project. Among the benefits are control of drainage basin water levels, allowing for timely drainage to maximize crop development or wetland control and improved water quality.
The drainage control reduces the annual transport of nitrogen to benefit waterfowl breeding habitats by increasing water depths to create a better vegetation cover. It also limits nitrogen levels and total suspended solids in watersheds. The watertight, gasketed Nyloplast and joints help to make sure that water loss is minimized during this transfer process.
At the Table Mountain Casino & Hotel Project, storm water enters through the catch basin at the top of each inlet then drops down and goes out of the bottom end. No diverters or reducers are required. The water is retained in the basins on site.
“In this granular soil, it tends to suck up the water pretty good,” said Krieger.
Decomposed granite (DG) was chosen as the bedding material because it backfills well. DG is like gravel but it is finer and generally more stable, making it ideal for hardscaping. The material is formed from natural weathering and erosion of solid granite, a hard igneous rock.
The storm water system includes InsertaTee lateral connections, 17,500 linear feet of 18-inch plus 20,200 feet of 12-inch AdvanEDGE corrugated high-density polyethylene (HDPE) pipe. This perforated pipe meets ASTM D700 and was designed to be installed on its edge to provide the largest possible drainage profile while reducing the width of the trench. Additionally, to collect and move the storm water runoff, 6,560 feet of 12-, 18- and 24-inch ADS N-12 corrugated HDPE pipe was installed throughout the site.
The 32-inch-wide trenches were cut into loam soils, to depths of between 4 and 12 feet, backfilled with ¾-inch crushed rock and covered with sand.
“It truly showed the flexibility of Nyloplast basins for field adjustments and partnered with InsertaTee and the ADS pipe allows for quick seamless modifications,” Krieger concluded.