During improvements to the Lake Elsinore channel, the Army Corps of Engineers raised land along the channel out of the flood way. Available land is at a premium in California, so these improvements open the area up to commercial development that brought much needed businesses and jobs to the city.
Triple J Associates, a land development company, began the Pasadena Street Industrial development project in this area. The President of Triple J Associates, Carl Johnson, had identified the area as a natural fit for his development strategy; developing and selling smaller parcels with industrial buildings between 5,000 and 10,000 square feet. A total of 28 buildings were planned for the 15-acre site at a total cost of $20 million.
The initial $8 million phase included 12 light-industrial buildings with on-site parking. During this phase, Triple J Associates was faced with addressing the environmental needs of a sensitive watershed while maximizing the land available for use.
Stormwater runoff from the Pasadena Street Industrial site was to be discharged from two outlet points into the Lake Elsinore channel, which holds the over flow from Lake Elsinore. The sensitive watershed ultimately connects to the Santa Ana River— which has been impacted by non-point pollution that affects the quality of the River.
Discharging to the River and the Lake Elsinore channel, a wetland, meant that the Triple J Associates had to address both the requirements of a stormwater permit from the Santa Ana Regional Water Quality Control Board and a 404 permit from Army Corp of Engineers.
Working with Madison Civil Engineering, led by Project Manager Christopher Hahn, Johnson evaluated the options available for meeting the stringent requirements of both agencies. In addition to removing trash, both the Army Corp and the Santa Ana Regional Water Quality Control Board wanted a system that was capable of removing sediment and several specific nutrients. In specifying a stormwater treatment system, the protection of water quality had to be balanced with the developer’s need to maximize the land available for use.
Said Hahn, “We came up with a couple of alternatives. We tried fitting a retention water quality basin in the site, but from a feasibility standpoint there wasn’t enough room to locate it and still make the project worthwhile.” “I would have had to buy adjacent property to store all this water on,” said Johnson.
“I would have had to purchase a three acre parcel for the retention basins.”
From previous projects, Hahn knew of an innovative passive filtration system that meets the level of pollutant removal required by the Army Corps and the Santa Ana Regional Water Quality Control Board — the Stormwater Management StormFilter. Unlike the detention ponds that had been considered, the StormFilter is installed underground and is easily accessible using a traffic-bearing lid installed at ground level – providing significant land savings.
Contech suggested using a dual treatment system - combining the StormFilter system with a StormScreen system, which removes trash and debris larger than 2400 microns through direct screening. The StormGate highflow bypass, which features a field adjustable weir, was used to split the flows between the StormScreen and StormFilter.
The site was split into two basins. Basin A consists of 16.2 acres, and Basin B includes 2.8 acres. At each basin, the StormGate bypasses high flows to the StormScreen while directing low flows to the StormFilter. In addition to providing the necessary amount of head, the StormGate also addressed possible flooding issues.
The StormFilter cartridges are filled with perlite, a naturally occurring puffed volcanic ash. Its porous, multicellular structure and rough edges make Perlite effective for removing suspended solids, oil and grease. All of the systems were installed underground. Using traffic bearing lids allows the systems to be located in parking lots and roadways. One StormFilter was located in a parking stall, and another at the end of a cul-de-sac. Hahn worked with technical sales engineers at Contech in what he described as a collaborative effort to address the specific design issues during the development stage, including a lack of head.
“We were severely limited on the amount of head that could develop through the system,” said Hahn. “Working back and forth with Contech, they came up with a diversion structure that allowed us to work with what we had.”
In the end, the dual systems allowed Triple J Associates to meet permit requirements for pollutant removal while maximizing land use. Additionally, since the StormFilter, StormScreen, and StormGate are all installed underground, they do not impact the aesthetics of the development.
“It’s probably one of the better looking industrial parks in the area,” said Hahn. “The way that it’s set up is conducive to good traffic flows, plus visually it’s appealing from the curb.”