Table Of Content

DAM FRENCHMAN MANUAL FOR OPERATION AND MAINTENANCE STATE DOCUMENTS COLLECTION uuN 0 7 2001 MONTANA STATE LIBRARY. 1515 E. 6th AVE. HELENA, MONTANA 59620 STATE WATER PROJECTS BUREAU WATER RESOURCES DIVISION DEPARTMENT OF NATURAL RESOURCES AND CONSERVATION 48 NORTH LAST CHANCE GULCH BOX P.O. 201601 MT HELENA, 59620-1601 Initial Publication May 2001 3 0864 0015 5832 2 DAM FRENCHMAN MANUAL FOR OPERATION AND MAINTENANCE STATE WATER PROJECTS BUREAU WATER RESOURCES DIVISION DEPARTMENT OF NATURAL RESOURCES AND CONSERVATION 48 NORTH LAST CHANCE GULCH P.O. BOX 201601 MT HELENA, 59620-1601 Initial Publication May 2001 Digitized by the Internet Archive 2015 in https://archive.org/details/frenchmandammanu2001mont TABLE OF CONTENTS Page OVERVIEW 1 Frenchman Reservoir Location Map (Figure 3 1) Frenchman Project Map (Figure 2) 4 Frenchman Dam General Layout (Figure 3) 5 Frenchman Dam Access Routes (Figure 4) 6 STATISTICAL INFORMATION 7 OPERATING PROCEDURES 11 Method and Schedule of Operation 11 Safe Drawdown 12 Limits of Appurtenances 12 Dam Operator 13 Storage Determination 14 Weather Monitoring 14 Interaction with Other Dams 14 Emergency 15 INSPECTION AND MONITORING 17 Structural Features Inspection 17 Riprap Inspection 18 Seepage Monitoring 18 MAINTENANCE 19 Routine Maintenance 19 Annual Maintenance 20 Record Keeping .....20 REFERENCES 23 APPENDICES 25 A. RATING CURVES AND TABLES Al Table SLOPE/ELEVATION/STORAGE TABLE A2 1 . Table 2. ACTIVE STORAGE TABLE A3 Table 3. OUTFLOW RATING TABLE A4 Table 4. SPILLWAY AND DIKE RATING CURVE AND TABLE A5 B. INSPECTION REPORT FORM Bl C. DISTRIBUTION LIST CI D. PROJECT DRAWINGS Dl 2001 i 2001 11 OVERVIEW The project is located on Frenchman Creek tributary of the Milk River in Phillips County. The project is located about 22 miles north of Saco, Montana (see Figures 1 and 2). Figure 3 provides a general layout of the dam, spillway and outlet works. Figure 4 is a map of the access routes to the dam. Frenchman Dam is owned by the Montana Department of Natural Resources and Conservation (DNRC) and is managed by the State Water Projects Bureau (SWPB) of the DNRC. The Frenchman Water Users Association (herein called the "association") operates and maintains the dam. The original earthfill dam was first completed in 1951. The dam failed on April 15, 1952 due to very high stream flows resulting from rapid snowmelt, which caused a very rapid filling of the reservoir. The dam was reconstructed in 1952-1953 with a larger spillway and revisions to the seepage cutoff. The dam is 44 feet high and 2, 100 feet long with a dike on the west end 8 feet high and 1,000 feet long. The reservoir stores 3,752 acre-feet at spillway crest and 13,540 acre-feet at dam crest. The dam's outlet works consists of a 60-inch diameter concrete outlet pipe, and two wet wells containing a 60-inch diameter emergency slide gate and a 60-inch operating slide gate. There is also a 24-inch diameter irrigation outlet in the downstream wet well. Both gates are controlled from the top of the tower in a gatehouse. The maximum capacity of the outlet works is 505 cubic feet per second (cfs), and 40 cfs from the 24-inch diameter irrigation outlet. 2001 1 The spillway is a reinforced concrete chute having a 1 19.0- foot wide crest (less bridge piers). The maximum capacity of the spillway is 17,500 cfs at the minimum dam crest. Water from the reservoir is primarily used for agricultural irrigation. The reservoir is also used for water-based recreation and the regulation of stream flow rates. 2 2001 3 2001