City, water district study sustainable water supply project

The Tehachapi-Cummings County Water District board of directors has authorized the district to work with the city of Tehachapi to explore the development of a self-sustaining water recycling system for the municipality. Under the plan, the city would convert effluent from the waste water (sewage) plant to potable domestic water for residential use.

"This would ensure that the city has water for the future," Tehachapi Public Works Director Don Marsh told the water district board on April 17. The board voted to write a memorandum of understanding (MOU) with the city to explore the feasibility of the city using the district's Blackburn Dam as a central element of the project.

The plan, the engineering of which was approved by the Tehachapi City Council on April 1, would pump treated effluent from the city's waste water treatment plant to Blackburn Dam. There, the effluent would percolate into the aquifer, going deeper and deeper until it becomes part of the Tehachapi underground water basin. The city of Tehachapi would pull up that water – years later – by way of its six potable wells and deliver it to city residents, filtered by nature and cleansed by time.

The earthen dam, which is a stadium-size basin at the bottom of the Blackburn Canyon watershed adjacent to the glider port, was built for flood control and is almost always dry. It has not been used as a spreading basin for groundwater recharge.

Currently, Tehachapi disposes of its waste water, which is treated to the secondary level, by spreading it in the summer on fodder crops in fields at the airport and holding it in the winter at a pond that is known as the Borrow Pit, near Steuber Rd. (It's called Borrow Pit"because Caltrans borrowed the dirt to make Hwy. 58 and left a hole).

The proposed project requires a new pump station and upgraded tertiary treatment facility at the waste water plant, a new pump station at the Borrow Pit and a pipeline from the Borrow Pit to the spreading ground at Blackburn Dam.

The project would provide a supplemental 1,000 acre feet (AF) a year the city could extract without impacting the safe yield, which is the amount that can be drawn annually from the basin without depleting it. The additional water also would ease reliance on State Water Project water.

Marsh said the project would enable the city to put its waste water to "a higher and better use than what we are using it for... The native safe yield will not change and the pumping rights will not change."