Research Problem and Background:
The number of cases of piping problems in Reclamation embankment structures demonstrates that improved methods for remediation grouting of piping are needed. As the average age of Reclamation dams increases, the original methods of preventing seepage around structures are exposed to forces that erode material. Seepage and piping problems will increase as these forces continue to act over time.

Project Objectives:
Possible uses of different grouts and grouting techniques in piping situations to find and fill piping conduits needed to be determined to prevent failures and accidents. The first step was to determine the state-of-the-industry of remedial grouting piping techniques that can be applied to Reclamation’s unique infrastructures. Laboratory investigations were conducted. Project funds were obligated for two field programs to help determine which methods and materials can be readily adapted to meet our needs.

Overall Outcome or Conclusions:
After a very thorough review of methods for remediation grouting of piping and how they pertain to Reclamation structures, we developed the following conclusions:

A wide variety of grouting techniques and materials are available for remedial grouting. There are many materials available for remedial grouting of piping, but little information on methods for remedial grouting of piping is publically available. Modification of grouting methods to seal fractures and cracks in concrete and rock are a good starting point for developing methods to seal piping conduits associated with embankments. These modified methods need to be fully evaluated and tested under controlled conditions to determine their effectiveness.

Remedial grouting to decrease water loss is far more difficult than grouting foundations for original or new construction. Additionally, involvement with dam safety modifications has demonstrated a need for a thorough understanding of the usage and behavior of chemical grouts, such as polyurethane resins, silicates, acrlyamides, and acrylates, to block seepage through rock and soil foundations and fills. Special grouts, grout additives, and application procedures are needed to successfully remedy these situations.

Improved methods are needed to identify piping conduits in embankment dams. A key element in remedial grouting of piping is intercepting the piping conduit. Once that is done, materials can be selected and proportioned to stop leaks.

Partners
Montana Area Office, Provo Area Office provided candidate field sites to test methods.

Publications and/or Other Deliverables
Internal Reports:
1) Report on laboratory tests of modules grouted in a soil box.
2) State-of-the-art paper on remedial grouting of piping
3) Report summarizing repair of leaking seal at Willow Springs Dam,
Montana
4) Report summarizing repairs of leaks under spillway at Beaver Dam,
Utah

External Publications:
Harris, David W., Kurt von Fay, and Nathan Snorteland. 1998. A Laboratory Simulation of In-Situ Grouting Using Portland Cement and Polyurethane Materials with Standard Methods. Annual Conference of the Association of State Dam Safety Officials, Las Vegas, Nevada, October 11-15, 1998