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DNRC Headquarters
1539 Eleventh Ave. Helena, MT 59601
Phone: (406) 444-2074 | Fax: (406) 444-2684
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Technical References

Filters and Drains

Filters for Embankment Dams – Best Practices for Design and Construction
Developed by FEMA, ASDSO, USBR, FERC, NRCS and USACE, this document provides procedures and guidance for best practices concerning embankment dam filter design and construction and represents an effort to collect and disseminate current information and experience having a technical consensus. This document is intended for use by personnel familiar with embankment dams, such as designers, inspectors, construction oversight personnel and dam safety engineers.
Gradation Design of Sand and Gravel Filters (NRCS Part 633 National Engineering Handbook, Chapter 26) Chapter 26 presents criteria for determining the grain size distribution (gradation) of sand and gravel filters needed to prevent internal erosion or piping of soil in embankments or foundations of hydraulic structures.
Filter Diaphragms (NRCS Part 628 National Engineering Handbook, Chapter 45)
Chapter 45 presents criteria for design and installation of filter diaphragms around outlet conduits.
Getting Water Into Pipes – Not As Easy As It Seems (Mark Pabst, 2007)
Although it is generally been believed that water can flow freely into collector pipes from clean, free-draining surrounding soils, this has been found not to be true in all cases. The paper addresses the practical aspects of flow into drain pipes associated with embankment dams.
Plastic Pipe Used in Embankment Dams (Chapter 4 from FEMA 675 Technical Manual)
This chapter presents methodology for the structural design of the drainpipe and the hydraulic design for the collection of water into the drainpipe. This chapter also discusses the relationship between soil backfill and the drainpipe.
Chimney Filter / Drain Design and Construction Considerations
This technical note was developed by URS Corporation for the Montana Dam Safety Program to provide engineers practical guidance for the design and construction of chimney filter and drainage features for embankment dams. The focus is on small embankment dams facing outlet replacement.

Contact Dam Safety
Dam Safety
DNRC Water Resources
1424 9th Avenue
PO Box 201601
Helena, MT 59620-1601


Bureau Chief
(406) 444-6816

Michele Lemieux, PE
Dam Safety Program Manager / Civil Engineer
(406) 444-6613

Chadrick Hill 
Civil Engineering Specialist
(406) 444-1358

Administrative Support
(406) 444-0862

Helena Regional Office
(406) 444-9724

Havre Regional Office
(406) 265-5516

Sam Johnson, PE
Billings Regional Office
(406) 247-4423

Larry Schock, CFM
Missoula Regional Office
(406) 542-5885

Marc Pitman, PE CFM
Kalispell  Regional Engineering Specialist
(406) 752-2713

Sterling Sundheim, CFM
Lewistown Regional Office
(406) 538-7459

, EI
Bozeman Regional Office
(406) 556-4508