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of Engineers report done for the Animas River basin. This report also determines the average <br />velocity of the 100 year peak flow event to be 8 feet/second. In designing the size of the <br />boulders used in the rock jetty, the uppermost tier of boulders (2 boulders) would be the <br />weakest since they do not have the weight of any boulders above them. The size of the boul- <br />ders were analyzed using the CSU procedure, which sums the moments around a pivot point <br />and calculates the turning forces in a given condition to determine a safety factor. A safety <br />factor is calculated for a boulder in a normal bed and on a sideslope. The calculations are pre- <br />sented below: <br />Project Name: THOMAS PIT JETTY <br />Date: l13/05/02 By: GL <br />Description: JETTY OF 5' DURABLE ROCK FOR 100 YR EVENT <br />ASSUME FLOW IS 11.5 FEET HIGH OR 6.5 FEET <br />ABOVE UPPERMOST BOULDER <br />TEST 1 RIPRAP STREAMBED LINING CSU PROCEDURE <br />INPUT D= 11.5 Depth of flow feet <br />INPUT Y= 62.4 Density of water Iblcu.ft. <br />INPUT S= 0.00734 slope of channel %/100 <br />T= Tractive force Ib/cu.ft. <br />T= 5.267184 =(D*Y'S) <br />N= Stability = 21T no units <br />Parameter Y(SG-1)Dso for turbulent flow <br />INPUT Dso= 4.5 Average diameter of riprap in feet <br />SG= 2.65 Specific Gravity of the rock used <br />from above N= 0.238735 <br />INPUT 0= 70 Angle of repose of riprap Degrees <br />INPUT Z= 0.41997 Bedslopa angle Degrees <br />SF(BOTTOM)= 4.142336 cos(Z)*tan(O) SAFETY FACTOR <br />sin(O)+N*tan(O) <br />BOTTOM RIPRAP IS STABLE <br />TEST 2 <br />INPUT A= <br />INPUT SS= <br />B= <br />N'= <br />SF(BANK)= <br />Thomas Pit 2/02 <br />RIPRAP BANK LINING CSU PROCEDURE <br />0.41997 Angle of streamline (bed) assuming uniform flow <br />(same as bedslope angle Z) DEGREES <br />63.43 sideslope angle <br />20.08714 tan's (cos(A)/(2•sin(A)/N'tan(O)+sin(A)) <br />0.365694 <br />0.161165 N• (1+SIN(A+B)/2) BANK STABILITY PARAMETER <br />2.054569 cos(A)*tan(O) 2.747404 <br />N'han(O) + sin(SS)"cos(B) 1.337217 <br />BANK RIPRAP (JETTY ROCK) IS STABLE <br />15 <br />Received <br />MAR072~82 <br />Durango Field OffiCl3 <br />Division of Minerals & Geology <br />