View Full Table | Close Full ViewTable 1.

Flow volumes of water passing through the gypsum filter bed and total dissolved phosphorus removal (chemical efficiency) for individual storm events.

 
Storm event date Filtered flow Chemical efficiency based on concentration
Chemical efficiency based on load
Influent TDP† Effluent TDP Removal Influent TDP Effluent TDP Removal
L × 103 mg L−1 % kg %
13 Apr. 2007 16 0.056 0.032 42 0.001 0.001 54
18 Apr. 2007 571 1.576 1.073 32 0.811 0.503 38
6 June 2007 2 0.171 0.012 93 0.001 0.001 100
30 July 2007 57 0.879 0.289 67 0.129 0.027 79
22 Aug. 2007 97 1.000 0.700 30 0.098 0.064 35
8 Feb. 2008 158 0.200 0.136 32 0.031 0.025 21
20 Feb. 2008 366 0.365 0.330 10 0.220 0.210 42
28 Apr. 2008 340 0.578 0.266 54 0.229 0.116 49
9 May 2008 148 1.581 0.405 74 0.319 0.104 67
16 May 2008 87 0.576 0.241 58 0.154 0.028 82
5 June 2008 315 1.721 0.310 82 0.540 0.106 80
5 July 2008 170 1.843 0.255 86 0.314 0.050 84
11 Dec. 2008 484 1.111 0.759 32 0.635 0.393 38
15 Mar. 2009 124 0.616 0.281 54 0.077 0.034 56
6 Apr. 2009 230 0.722 0.548 24 0.166 0.093 44
11 Apr. 2009 201 0.810 0.734 9 0.104 0.076 27
14 Apr. 2009 318 0.526 0.607 −15 0.081 0.090 −11
18 June 2009 225 1.909 0.078 96 0.014 0.001 96
3 Aug. 2009 68 1.871 0.128 93 0.127 0.009 93
12 Aug. 2009 146 1.207 0.057 95 0.157 0.009 95
24 Aug. 2009 256 2.231 0.065 97 0.571 0.016 97
10 Sept. 2009 255 0.985 0.064 93 0.274 0.014 95
17 Oct. 2009 1 1.196 0.049 96 0.316 0.013 96
12 Nov. 2009 263 1.033 0.040 96 0.396 0.015 96
9 Dec. 2009 73 0.234 0.035 85 0.060 0.005 91
23 Jan. 2010 118 0.729 0.021 97 0.086 0.002 97
29 Mar. 2010 16 0.821 0.013 98 0.013 0.001 98
9 Apr. 10 27 1.860 0.011 99 0.050 0.001 99
1 Oct. 10 285 1.433 0.577 60 1.314 0.545 59
Mean 1.029 0.280 0.251 0.088
Total dissolved phosphorus.
Dates in italics indicate that storm flow did not breach the weir. All flow passed through the gypsum bed.



View Full Table | Close Full ViewTable 2.

Total ditch flow volumes, percent of total flow passing through the filter bed, influent and effluent total dissolved phosphorus, and total dissolved phosphorus removal as a proportion of total phosphorus load entering the ditch filter system (system efficiency) for individual storm events.

 
Storm event date Total ditch flow Influent TDP† Effluent TDP Removal
L × 103 (% of total flow) kg %
13 Apr. 2007 16 (100) 0.001 0.000 54
18 Apr. 2007 7879 (7) 13.807 13.498 2
6 June 2007 2 (100) 0.000 0.000 100
30 July 2007 57 (100) 0.129 0.027 79
22 July 07 97 (100) 0.098 0.064 35
8 Feb. 2008 454 (35) 0.113 0.084 25
20 Feb. 2008 1328 (28) 0.730 0.520 29
28 Apr. 2008 406 (84) 0.312 0.200 36
9 May 2008 183 (81) 0.464 0.249 46
16 May 2008 87 (100) 0.154 0.028 82
5 June 2008 2326 (14) 3.900 3.466 11
5 July 2008 250 (68) 0.516 0.252 51
11 Dec. 2008 2336 (21) 3.412 3.169 7
15 Mar. 2009 124 (100) 0.077 0.034 56
6 Apr. 2009 592 (39) 0.681 0.609 11
11 Apr. 2009 800 (25) 0.599 0.571 5
14 Apr. 2009 1289 (25) 0.299 0.299 0
18 June 2009 233 (97) 0.082 0.068 17
3 Aug. 2009 148 (46) 0.127 0.009 46
12 Aug. 2009 439 (33) 0.157 0.009 33
24 Aug. 2009 1876 (14) 0.571 0.016 16
10 Sept. 2009 2953 (9) 3.453 3.193 8
17 Oct. 2009 3 (9) 3.703 3.399 8
12 Nov. 2009 9237 (3) 10.974 10.593 3
9 Dec. 2009 3416 (2) 1.542 1.487 4
23 Jan. 2010 2135 (6) 1.460 1.376 6
29 Mar. 2010 848 (2) 0.657 0.644 2
9 Apr. 2010 82 (33) 0.150 0.100 33
1 Oct. 2010 1202 (24) 1.720 0.951 45
Total 51.87 47.11
Total dissolved phosphorus.
Dates in italics indicate when storm flow did not breach the weir. All flow passed through the gypsum bed.



View Full Table | Close Full ViewTable 3.

Ditch flow, total dissolved phosphorus loads, and phosphorus removal efficiencies by year of operation.

 
Year Apr.–Dec. 2007 Jan.–Dec. 2008 Jan.–Dec. 2009 Jan.–Dec. 2010
Total ditch flow, L × 103 11.6 12.8 75.9 27.3
Ditch flow passing through the filter, L × 103 4.3 7.0 13.2 4.6
Ditch flow passing through the filter, % 37 55 17 17
TDP† in ditch flow, kg 8.6 13.3 48.2 22.8
TDP removed, kg 2.2 4.4 9.8 4.0
System efficiency based on load, % 25 30 20 17
Chemical efficiency based on load, % 68 57 84 89
Total dissolved phosphorus.