Research Problem and Background:
Typically, 30 to 50 percent of irrigation water is lost through canal seepage, with the most severe (angular) soil conditions accounting for the highest seepage rates and the most design challenges. Canal-lining technologies are needed that can minimize seepage losses at reasonable costs. Low-tech lining systems that can be installed by irrigation district forces offer the most promise. Test sections will be evaluated for effectiveness and long-term durability.

Project Objectives:
Identify lining options best suited for use on Reclamation facilities. Determine effectiveness, design life, maintenance costs, life-cycle costs, seepage rates, and cost of conserved water ($/acre-foot) for each test section.

Overall Outcome or Conclusions:
Test sections are being evaluated for effectiveness and long-term durability. Effectiveness is determined by comparing pre-construction and post-construction seepage rates as measured by full-scale ponding tests. The ponding tests are repeated after 5 and 10 years of service to determine long-term effectiveness. All the test sections are being inspected every 6 to 12 months to ascertain condition, collect maintenance data, and predict durability. Life-cycle costs will be calculated from initial construction costs, maintenance costs, and life expectancies. Finally, the cost of conserved water will be calculated ($/acre-foot) for use in cost/benefit analysis.

Ponding tests on the new test sections (1993) showed that seepage had been reduced by 90 to 99 percent, depending on the lining material. The 5-year ponding tests (1998) showed some increase in seepage with age; however, seepage rates have still been reduced by 80 to 95 percent, depending on the lining material. Preliminary life-cycle costs and conserved water costs will be calculated for the 7-year report

Ten-man crew installs exposed geomembrane over a geotextile cushion

Partners:
PN Region provided about $2 million for construction of 23 test sections, and an additional $400,000 for Jack Haynes as co-investigator. Geosynthetic Manufacturers provided about $1 million in lining materials and technical expertise during the construction of the test sections, plus an additional $100,000 for maintenance and repair of the test sections. Five irrigation districts (North Unit, Arnold, Tumalo, Lugert Altus, and Juniper Flat) provided about $100,000 of in-kind services during construction and maintenance of the test sections.

Publications and/or Other Deliverables
December 1993 - Article for USBR "Currents" Magazine
May 1994 - Construction Report (R-94-06)
September 1994 - Paper for 5th International Conference on Geosynthetics
December 1994 - 2-Year Durability Report (R-94-14)
December 1994 - Article for O&M Bulletin
December 1995 - Poster Session for GRI-9 Conference
January 1997 - 5-Year Durability Report (R-97-01)
October 1997 - 5-Year Ponding Report - Arnold Canal
February 1998 - DOE Report - Conductivity Studies to Locate Areas of High Seepage on the North Unit Canal December 1998 - 6-Year Ponding Report - North Unit Canal
April 1999 - Paper for Geosynthetics 99 Conference
September 1999 - 7-Year Durability and Supplemental Construction Report
September 2002 - Final Report