Aerial View of 19 Basins
Aerial View of 19 Basins Watered

Flowmeter Vault Construction
Flowmeter Vault Construction and Main Pipeline

Aerial Image of Basins Construction
High Aerial Image of Basins Construction

Spreading Basin
Spreading Basin in Operation

Introduction

The Tonopah Desert Recharge Project (TDRP) is a direct recharge project located in western Maricopa County, approximately 7 miles northwest of Tonopah, Arizona. The site is approximately 40 miles west of the City of Phoenix. Construction began in 2004 and the project began full-scale operations in January 2006.

The facility is located in the Hassayampa sub-basin of the west Salt River Valley Groundwater Basin. The project is located in the Phoenix Active Management Area, where groundwater use is regulated by the Arizona Department of Water Resources (ADWR).

The TDRP occupies 542 acres adjacent to the CAP canal 100 miles east of Havasu inlet on the Colorado River. The project includes a gravity turnout, delivering up to 300 cfs to the facility. The facility has 19 infiltration basins totaling about 207 acres in surface area.

TDRP Facts

  • Hydrologic feasibility assessments conducted from 2000 - 2003
  • Construction of TDRP started in 2004
  • Full-scale operations began in January 2006
  • Total construction cost: $13 million
  • Annual permitted volume: 150,000 acre-feet
  • Average infiltration rates are 4-5 feet per day
  • Basin infiltration area = 207 acres; 19 infiltration basins
  • Largest basin = 14.1 acres; Smallest basin = 6.6 acres
  • Sloped basin bottoms to reduce excavation
  • Gravity turnout with diversion capacity of 300 cfs
  • Remote operation and monitoring capability

Facility Components

The facility is served by a gravity turnout that provides water to an 84-inch diameter pipeline. The inflow to the project is measured by an acoustic flowmeter. The distribution pipeline ranges in size from 84-inch diameter to 24-inch diameter pipe.

The distribution pipeline is approximately two miles long. The pipeline serves 19 infiltration basins. Inflow to each basin is controlled by a motor operated plug valve and may be controlled remotely at the Control Center. Inflow to each basin is measured by an insertion flowmeter. Water levels in each basin are measured and monitored by pressure transducers.

The project design includes sloped basin bottoms. The slope of each of the 19 basins follows the natural gradient of the site. A minimum of 3 feet is excavated during construction. A typical basin has up to 4 feet of depth in the down-gradient portion of the basin and up to 1 foot of depth in the up-gradient end of the basin. Each basin includes an overflow spillway to protect from overflows.