Water Environment Federation (WEF)

Rold Model Water Recycling Program

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Courtesy of Courtesy of Water Environment Federation (WEF)

The Viejas Band of Kumeyaay Indians, a federally recognized tribe, vested with authority by the U.S. Environmental Protection Agency (USEPA), form the Tribal Government to regulate all activities concerning water quality issues within the reservation boundaries. The Reservation has 400 non-transient residents and an average of 5,000 transient residents. The transient population visits the Viejas Casino, an Outlet Mall and a Recreational Vehicle (R.V) Park. In 2001, the Viejas Tribal Government completed the Reservation Water and Sewer Master Plan. The Master Plan recommended improvements to the water distribution system a new wastewater collection system and a backbone recycled water distribution system. Most of the recommended water and sewer improvements have been designed, constructed and are in operation. The Master Plan water system improvements included new potable water reservoirs designed to operate at the same hydraulic grade line and with sufficient capacity to serve both the Viejas Indian Reservation and the casino and Outlet Mall. Wastewater generated within the Reservation is treated at the Reservation’s Viejas Water Reclamation Plant (VWRP). The VWRP uses ultra filtration membrane technology and disinfection using sodium hypochlorite to produce tertiary quality effluent. The VWRP effluent meets and exceeds all recycled water quality standards for unrestricted landscape irrigation. Until late last year, VWRP effluent was used to meet in-plant washwater demands and to irrigate fields in the vicinity of the plant. Excess VWRP effluent exceeding irrigation demands was conveyed to percolation ponds for disposal.

Two years ago the VWRP was expanded from 200,000 gallons per day (GPD) to 300,000 GPD and additional facilities were designed and constructed to expand the recycled water distribution system. Construction of these facilities would allow Viejas Tribal Government to expand their water conservation plan by using high quality tertiary effluent to irrigate landscaped areas with recycled water.

To reduce the capital cost to expand the recycled water distribution system and to minimize disruption to the Tribal members and transient population, the Master Plan recommended integrating into the upgraded recycled water system existing facilities that have been abandoned as result of recent water and sewer system improvements. The existing recycled water (RW) distribution system includes 8-inch pipelines located on the south side of Browns Road and crossing Viejas Creek utility bridge and terminating on the eastern side of the Viejas Creek at the VWRP. Existing wastewater facilities to be integrated into the recycled water distribution system include the 8-inch wastewater force main that used to convey the casino wastewater to the VWRP. The force main was abandoned when a new pump station and force mains to serve the casino started operation. Other facilities were incorporated into the recycled water distribution system include the two abandoned 400,000-gallon water reservoirs, booster pump station, and engine driven fire pump station that used to serve the Casino and Outlet Mall loop. These pump stations and reservoirs were abandoned when the new water reservoirs and water distribution system were completed. The Public Works Department relocated the engine driven fire pumps from the business enterprise site to an area next to the 50,000-gallon recycled water storage tank located at the VWRP.

The total acreage being served by the upgraded recycled water distribution system is 31 acres with a potential of serving fifteen acres in the future. The recycled water system and proposed improvements had been modeled using H2ONet Modeling software to confirm that both abandoned water distribution system pipelines and booster pump station, and wastewater facilities can be integrated with the existing recycled water facilities into a single system. New pipelines have been added to better serve the distribution network. A 6-inch recycled water line 900 feet long is provided to supply landscape irrigation system in the Outlet Mall. The pipeline has been constructed using directional drilling to minimize any inconvenience or shut down affecting the customers and the residents. Landscape irrigation system modifications also includes cross connections inspection and testing to ensure safety and compliance with Health Service Department requirements. Existing irrigation system controllers, irrigation system stations and irrigation heads have been converted to comply with RW regulations. Approximately 15 irrigation controllers have been retrofitted. On the average each system controller operates 26 irrigation system stations and each station serves 20 irrigation heads. Now Viejas is recycling 100% of the water collect in the sewerage system for landscape irrigation and utilizing available storage to avoid the use of potable water for irrigation any where in the reservation.

The Viejas Band of Kumeyaay Indian is a federally recognized tribe and is represented by a Tribal Government. The Viejas Reservation, located in Alpine, California, in the eastern part of San Diego County, has an ultimate permanent population of about 750. The Reservation has a 210,000 square feet casino, an outlet mall with more than 50 stores and an RV Park. The Tribal Government is vested with authority by the United States Environmental Protection Agency (USEPA) to regulate all activities concerning water quality issues within the reservation boundaries. Sewer lines, lift stations and an extended aeration package plant installed in 1996 provide sewage collection and treatment for the casino and outlet stores. The residences and RV Park are connected to septic tanks.

The original Viejas extended aeration wastewater treatment plant was designed for tertiary treatment of 150,000 gallons per day (gpd). The plant included secondary clarification, flocculation, sand filtration and chlorination. The plant however, could not attain tertiary effluent quality with flows over 70,000 gpd. In 1999, the Tribal Government hired HDR Engineering (HDR) to undertake the task of evaluating the treatment process and designing temporary improvements to the plant to ensure compliance with Tribal Government goals. In a second phase, in 2000, HDR designed process changes to increase treatment capacity to 200,000 gpd to accommodate commercial enterprise expansions. In this phase, Immersed Membrane Bioreactors were retrofitted in the existing plant. Finally, as part of a third phase, HDR completed the plant modifications to increase the plant capacity to 300,000 gpd, to accommodate commercial growth and connect residences and the recreational vehicle (RV) Park. Additionally, design is now completed to use reclaimed effluent for landscape irrigation at the casino and outlet mall.

This paper discusses the engineering aspects of the planning, implementation and commissioning of the water wastewater and recycled water infrastructure program in Viejas. The program included the upgrade of the water distribution and storage system, water reclamation plant modifications, new sewage collection system and recycled water for landscape irrigation.

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