OAEA *T I M TIME OF TRAVEL STUDIES: AVERAGE AND HIGH FLOWS RIVER OCK Miss V Johnson Consultancy Services AEA Technology 1 7 ^ 364 Harwell, Didcot Oxfordshire 0X11 ORA E n v i r o n m e n t Ag e n c y DATE DUE NATIONAL LIBRARY & 23 AUG 2000 INFORMATION SERVICE HEAD OFFICE Rio House, Waterside Drive. Aztec West, Almondsbury, Bristol BS32 4UD May 1993 D*mco, Inc 38-293 _ AGENCY 052190 Time of Travel Studies: Average and High Flows for the River Ock Table showing the velocity of the tracer for each stretch at average and high flows and for average and peak arrival time 1 1 ! 1 | Reach j Average Flow Conditions High Flow Conditions ; 1 t I i < i 1 1 i i | From TO Reach | Peak Average Velocity of Tracer Velocity of Tracer Peak Average Velocity of Tracer J Velocity of Tracer j 1 Length | Arrival Arrival at Peak Arrival Time at Average Arrival Time Arrival Arrival at Peak Arrival Time at Average Arrival Time | 1 (km) | Time Time , (cm/s) (cm/s) Time Time (cm/s) ' (cm/s) 1 1 'I i i * ' | (mins) (mins) (mins) (mins) 1 1 1 1 :i ! : i 1 ! 1 :l 1 1 ! | 1 1 ! 1 | Wantage STW East Hanney ll 36 | 79 81 28.69 27. 98 71 73 31.92 | 31.05 | I 1 1 j East Hanney Venn Mill 3.70 | 227 229 27.17 26.93 235 236 26.24 25.91 | 1 1 1 1 I ! | Venn Mill Marcham 3' 10 | 262 266 19.72 19.42 245 247 21.09 j 20.92 | 1 1 1 I 1 1 | Marcham R .Thames 4 .79 | 449 452 17.78 17.66 318 315 25.10 | 25.34 | I 1 1 1 1 Time of Travel Studies: Average and High Flows for the River Ock Table showing the velocity of the tracer for each stretch at average and high flows and for average and peak arrival time i1 1 1 | Reach Average Flow Conditions High Flow Conditions 1 i 1 1 1 | From TO Reach Velocity of Tracer Velocity of Tracer Velocity of Tracer Velocity of Tracer j 1 Length at Peak Arrival Time at Average Arrival Time at Peak Arrival Time at Average Arrival Time | 1 (km) (cm/s) (cm/s) (cm/s) (cm/s) j 1 1 1 1 1 1 1 1 | Wantage STW East Hanney 1.36 28.69 27.98 31.92 31.05 | 1 1 1 1 | East Hanney Venn Mill 3 .70 27.17 26.93 26 .24 25.91 | I 1 1 1 | Venn Mill Marcham 3.10 19.72 19.42 21.09 20.92 | 1 1 | Marcham R. Thames 4 .79 17.78 17.66 25 .10 25.34 | 1 1 1 - .........1 Time of Travel Studies: Average and High Flows for the River Ock Table showing the velocity of the tracer for each stretch at average and high flows and for average and peak arrival time 1 1 | Reach ;1 Average Flow Conditions High Flow Conditions 1 i , 1 1 1 ■ , ' ] From TO Reach (| Peak Average Velocity of Tracer Velocity of Tracer Peak Average Velocity of Tracer ' Velocity of Tracer | 1 Length ’J Arrival Arrival at Peak Arrival Time at Average Arrival Time Arrival Arrival at Peak Arrival Time at Average Arrival Time | 1 (km) | Time Time ^cm/s) (cm/s) Time Time (cm/s) ' (cm/s) ! | :i 1 | (mins) (mins) (mins) (tnins) ) i '1 i : ! 1 1 1 ■ 1 1 1 : i | Wantage STW Bast Hanney 1.36 | 79 81 28.69 27.98 71 73 31. 92 | 31.05 | 1 I 1 1 | East Hanney Venn Mill 3.70 | 227 229 27.17 26.93 235 238 26.24 | 25.91 | 1 1 I , 1 1 1 | | Venn Mill Marcham 3.10 | 262 266 19.72 19.42 245 247 21.09 [ 20.92 | i i 1 1 1 1 | Marcham R .Thames 4 .79 j 449 452 17.78 17.66 318 315 25.10 | 25.34 | .i 1 i 1 1 1 1 1 I Time of Travel Studies:1 Average and High Flows for the River Ock Table showing the velocity of,the tracer for each stretch at average and high flows and for average and peak arrival time 1 1 • | Reach Average Flow Conditions High Flow Conditions 1 1 1 '1 | From To Reach Velocity of Tracer Velocity of Tracer Velocity of Tracer Velocity of Tracer | 1 Length at Peak Arrival Time at Average Arrival Time at Peak Arrival Time at Average Arrival Time | 1 (km) {cm/s> (cm/s) (cm/s) (cm/s) | 1 1 1 1 1 1 1 1 | Wantage STW Bast Hanney 1.36 28.69 27.98 31.92 31. 05 | 1 'i 1 1 J East Hanney Venn Mill 3 .70 27.17 26. 93 26 .24 25. 91 | 1 1 1 1 | Venn Mill Marcham 3.10 19.72 19.42 21.09 20. 92 | ;i i 1 1 1 | Marcham R.Thames 1 4 .|79 17.78 17.66 25.10 25. 34 | 1 1 ) 1 - ...... 1 Time of Travel Studies: Average and High Flows for the River Ock f Table showing the velocity of the1 tracer for each stretch at average and high flows and Cor average and peak arrival time I I ! : i * | Reach | Average Flow Conditions High Flow Conditions ' ! ■ ! 1 1 ' ^ | From To Reach | Peak Average Velocity of Tracer Velocity of Tracer Peak Average Velocity of Tracer Velocity of Tracer | Length | Arrival Arrival at Peak Arrival Time at Average Arrival Time Arrival Arrival at Peak Arrival Time at Average Arrival Time | (km)' |'Time Time (cm/s) (cm/s) Time Time (cm/a) (cm/s) , I 1 1 j1(mins) (mins) (mins) (mins) •* ! : 1 11 i i : ' : 1 ' | Wantage STW East Hanney 1.36 ) 79 SI 28.69 27. 9B 71 73 31.92 1 31.05 | 1 1 1 | East Hanney Venn Mill 3 .70 ) 227 229 27.17 2S.93 235 238 26.24 , 25.91 | t 1 ( Venn Mill Marcham 3.10 j 262 266 19.72 19.42 245 247 21.09 j 20.92 | 1 1 , 1 ( | Marcham R .Thames 4.79 | 449 452 17.78 17.66 310 315 25.10 | 25.34 | 1 ■ 1 I ■ ! Time of Travel Studies: Average and High Flows for the River Ock ; i ( Table showing the velocity of‘the tracer for each (Stretch at average and high flows and for average and peak arrival time 1 1 1 | Reach - Average Flow Conditions High Flow Conditions 1 i 1 1 1 | Prom to ; Reach Velocity of Tracer Velocity of Tracer Velocity of Tracer Velocity of Tracer | 1 > Length at Peak Arrival Time at Average Arrival Time at Peak Arrival Time at Average Arrival Time | ■[ (km) (cm/s) ! (cm/s) (cm/s) < cm/s) | 1 i. 1 1 1 1 1 1 1 1 | wantage STVJ East Hanney 1 36 28.69 27. 98 31.92 31.05 | i 1 1 1 :l | East Hanney Venn Mill 3 70 27.17 26.93 26.24 25.91 [ i I I 1 | Venn Mill Marcham 3 10 19.72 ' 19.42 21.09 20.92 | I 1 1 [ Marcham R.Thames 4 79 17.78 17.66 25.10 25.34 | t 1 1 1 ■ v ' y Table of Contents 1 Introduction.................................................................................................I 2 Technical Details........................................................................................1 2.1 Tracer Release Protocol........................................................................... 1 2.2 Tracer Sampling Protocol......................................................................... 2 3 Notes on the reaches.................................................................................. 2 3.1 East Hanney................................................................................................2 3.2 Venn M ill................................................... ,............................................... 2 3.3 Marcham................................................... ..................................................3 ' 3 7 4 ^ '.Trrrrrrr.' rrr-. tt." r. 4 Results of the Time of Travel Study........................................................ 4 5 Conclusion.................................................................................................. 6 Map showing the location of rivers, sampling points, sewage treatment works and reaches used in the Ock time of travel study. Sampling point National Sewage River Reach used Key: (Number represents Grid Treatment in time of the last two Reference Work travel study numbers in URN i.e. POCR.OOO8) i i Kingston Bagpuize 90 ; - a 08 STW i (2700) i & 1 Introduction This report was prepared by Consultancy Services, AEA Technology, and addresses NRA's requirement to measure the 'time of travel' for both average and high flow conditions in specified reaches of the River Ock. Rhodamine WT was used as a tracer in-determining water's travel time, in terms of the time of first arrival, peak arrival time and the average time for a labelled plume to pass specified reaches of the River Ock. The results are based on measurements made during the dry period 3rd to 11th March 1993 for the average flow, when there had been little rainfall since the very wet January. The measurements involving high flow conditions were made on the 15th and 16th of April after a very wet Easter. The dates for carrying out the.studies were agreed with the NRA. 2 Technical Details 2.1 Tracer Release Protocol A solution of Rhodamine WT in 10 litres of water was introduced into the river at mid stream and/or where maximum turbulence existed. To ensure a rapid mix this was done by emptying the container within a very few seconds. The amount of tracer that needs to be added depends upon the potential dispersion of the dye between release and sampling point, the concentration on sampling having to be high enough to give a clear definition of the first and the peak arrival of the tracer. We assumed the length of dispersion to be 10% or more of the travel distance, and thus the amount of tracer used in each measurement was based on a volume of diluting water that allowed a dispersion of 10% of the travel distance, aiming at a concentration of tracer on sampling of maximum 20 ppb.