Briarwood Stormwater Pollution Load Reduction Report

The Briarwood Stormwater Treatment Facility (BSTF) was completed in 2012 in Venice, FL. Designed to treat surface water from a 65-acre wet detention pond between storm events, the treatment train includes physical and biological processes to reduce nitrogen loads to Alligator Creek. Water quality parameters are monitored monthly at BSTF to provide estimates of pollutant load reduction efficiency and inform on optimal operations. The results of the removal of total nitrogen and select nutrients are reported annually in the Sarasota County NPDES MS4 Annual Report.

Pollutant Load Reduction Reports

Pollutant Load Reduction Reports for the Briarwood Stormwater Treatment Facility are updated at least bi-monthly. These reports are generated utilizing water quality and flow data to calculate the estimated nitrogen load reductions for each month. The tables below contain the most recent 12 months of calculations. Reports are available for download for the entire period of record.

BOD, Biochemical oxygen demand

BSTF Pollutant Load Reduction Report for "BOD, Biochemical oxygen demand"
Year / Month Rainfall In (Wet well / Pump A) Out (Wet well / Pump B) Reduction Goal Percent Volume
Lost		 Percent BOD
Reduction
SARASOTA_ARMS - AL-1 (in) Volume (kgals) BOD conc. (mg/l) BOD load (lbs) Volume (kgals) BOD conc. (mg/l) BOD load (lbs) BOD (lbs) BOD (lbs)
2023 June 6.63 2,733 4.250 96 2,321 1.000 19 77 15.1 % 76.5 %
2023 May 0.69 2,819 6.170 145 2,399 1.630 32 113 14.9 % 73.6 %
2023 April 2.36 2,722 4.600 104 5,197 3.630 157 -53 -90.9 % 21.1 %
2023 March 0.70 1,375 4.650 53 0 4.700 -1.1 %
2023 February 0.07 422 3.970 13 0 2.840 28.5 %
2023 January 1.29 0 4.570 185 1.430 2 68.7 %
2022 December 0.83 46,471 4.120 1,597 40,513 3.580 1,210 387 12.8 % 13.1 %
2022 September 11.33 25,340 3.570 754 23,404 1.000 195 559 7.6 % 72.0 %
2022 August 8.85 27,231 7.390 1,679 22,255 5.100 947 732 18.3 % 31.0 %
2022 July 5.24 0 5.360 0 3.360 37.3 %
Totals 37.99 109,113 48.650 4,441 96,274 28.270 2,562 1,815 -3.7 % 42.1 %

Chlorophyll a, corrected for pheophytin

BSTF Pollutant Load Reduction Report for "Chlorophyll a, corrected for pheophytin"
Year / Month Rainfall In (Wet well / Pump A) Out (Wet well / Pump B) Reduction Goal Percent Volume
Lost		 Percent ChlaC
Reduction
SARASOTA_ARMS - AL-1 (in) Volume (kgals) ChlaC conc. (mg/l) ChlaC load (lbs) Volume (kgals) ChlaC conc. (mg/l) ChlaC load (lbs) ChlaC (lbs) ChlaC (lbs)
2023 June 6.63 2,733 32.900 750 2,321 3.350 64 686 15.1 % 89.8 %
2023 May 0.69 2,819 53.700 1,263 2,399 2.400 48 1,215 14.9 % 95.5 %
2023 April 2.36 2,722 27.700 629 5,197 0.839 36 593 -90.9 % 97.0 %
2023 March 0.70 1,375 37.400 429 0 1.190 96.8 %
2023 February 0.07 422 16.100 56 0 10.500 34.8 %
2023 January 1.29 0 86.500 185 2.490 3 97.1 %
2022 December 0.83 46,471 93.300 36,183 40,513 86.100 29,110 7,073 12.8 % 7.7 %
2022 September 11.33 25,340 128.000 27,068 23,404 7.630 1,490 25,578 7.6 % 94.0 %
2022 August 8.85 27,231 190.000 43,178 22,255 148.000 27,487 15,691 18.3 % 22.1 %
2022 July 5.24 0 42.900 0 7.990 81.4 %
Totals 37.99 109,113 708.500 109,556 96,274 270.489 58,238 50,836 -3.7 % 71.6 %

Nitrogen, Kjeldahl

BSTF Pollutant Load Reduction Report for "Nitrogen, Kjeldahl"
Year / Month Rainfall In (Wet well / Pump A) Out (Wet well / Pump B) Reduction Goal Percent Volume
Lost		 Percent TKN
Reduction
SARASOTA_ARMS - AL-1 (in) Volume (kgals) TKN conc. (mg/l) TKN load (lbs) Volume (kgals) TKN conc. (mg/l) TKN load (lbs) TKN (lbs) TKN (lbs)
2023 June 6.63 2,733 6.100 139 2,321 1.540 29 110 15.1 % 74.8 %
2023 May 0.69 2,819 2.130 50 2,399 2.170 43 7 14.9 % -1.9 %
2023 April 2.36 2,722 2.860 64 5,197 1.390 60 4 -90.9 % 51.4 %
2023 March 0.70 1,375 2.720 31 0 1.870 31.3 %
2023 February 0.07 422 2.260 7 0 2.080 8.0 %
2023 January 1.29 0 3.200 185 2.600 4 18.8 %
2022 December 0.83 46,471 2.440 946 40,513 1.870 632 314 12.8 % 23.4 %
2022 September 11.33 25,340 1.410 298 23,404 1.140 222 76 7.6 % 19.1 %
2022 August 8.85 27,231 3.420 777 22,255 2.330 432 345 18.3 % 31.9 %
2022 July 5.24 0 3.890 0 26.100 -571.0 %
Totals 37.99 109,113 30.430 2,312 96,274 43.090 1,422 856 -3.7 % -31.4 %

Nitrogen, Nitrite + Nitrate as N

BSTF Pollutant Load Reduction Report for "Nitrogen, Nitrite + Nitrate as N"
Year / Month Rainfall In (Wet well / Pump A) Out (Wet well / Pump B) Reduction Goal Percent Volume
Lost		 Percent NOx
Reduction
SARASOTA_ARMS - AL-1 (in) Volume (kgals) NOx conc. (mg/l) NOx load (lbs) Volume (kgals) NOx conc. (mg/l) NOx load (lbs) NOx (lbs) NOx (lbs)
2023 June 6.63 2,733 0.021 0 2,321 0.408 7 -7 15.1 % -1,842.9 %
2023 May 0.69 2,819 0.018 0 2,399 0.175 3 -3 14.9 % -872.2 %
2023 April 2.36 2,722 0.016 0 5,197 0.221 9 -9 -90.9 % -1,281.3 %
2023 March 0.70 1,375 0.029 0 0 0.438 -1,410.3 %
2023 February 0.07 422 0.019 0 0 0.421 -2,115.8 %
2023 January 1.29 0 0.083 185 0.015 0 81.9 %
2022 December 0.83 46,471 0.011 4 40,513 0.014 4 0 12.8 % -27.3 %
2022 September 11.33 25,340 0.008 1 23,404 0.211 41 -40 7.6 % -2,537.5 %
2022 August 8.85 27,231 0.030 6 22,255 0.155 28 -22 18.3 % -416.7 %
2022 July 5.24 0 0.006 0 0.439 -7,216.7 %
Totals 37.99 109,113 0.241 11 96,274 2.497 92 -81 -3.7 % -1,763.9 %

Nitrogen, Total

BSTF Pollutant Load Reduction Report for "Nitrogen, Total"
Year / Month Rainfall In (Wet well / Pump A) Out (Wet well / Pump B) Reduction Goal Percent Volume
Lost		 Percent TN
Reduction
SARASOTA_ARMS - AL-1 (in) Volume (kgals) TN conc. (mg/l) TN load (lbs) Volume (kgals) TN conc. (mg/l) TN load (lbs) TN (lbs) TN (lbs)
2023 June 6.63 2,733 6.121 139 2,321 1.948 37 102 278 15.1 % 68.2 %
2023 May 0.69 2,819 2.148 50 2,399 2.345 46 4 278 14.9 % -9.2 %
2023 April 2.36 2,722 2.876 65 5,197 1.611 69 -4 278 -90.9 % 44.0 %
2023 March 0.70 1,375 2.749 31 0 2.308 278 16.0 %
2023 February 0.07 422 2.279 8 0 2.501 278 -9.7 %
2023 January 1.29 0 3.283 185 2.615 4 278 20.3 %
2022 December 0.83 46,471 2.451 950 40,513 1.884 636 314 278 12.8 % 23.1 %
2022 September 11.33 25,340 1.418 299 23,404 1.351 263 36 278 7.6 % 4.7 %
2022 August 8.85 27,231 3.450 784 22,255 2.485 461 323 278 18.3 % 28.0 %
2022 July 5.24 0 3.893 0 26.539 278 -581.7 %
Totals 37.99 109,113 30.668 2,326 96,274 45.587 1,516 775 278 -3.7 % -39.6 %

Phosphorus as P

BSTF Pollutant Load Reduction Report for "Phosphorus as P"
Year / Month Rainfall In (Wet well / Pump A) Out (Wet well / Pump B) Reduction Goal Percent Volume
Lost		 Percent TP
Reduction
SARASOTA_ARMS - AL-1 (in) Volume (kgals) TP conc. (mg/l) TP load (lbs) Volume (kgals) TP conc. (mg/l) TP load (lbs) TP (lbs) TP (lbs)
2023 June 6.63 2,733 0.228 5 2,321 0.044 0 5 15.1 % 80.7 %
2023 May 0.69 2,819 0.221 5 2,399 0.042 0 5 14.9 % 81.0 %
2023 April 2.36 2,722 0.366 8 5,197 0.072 3 5 -90.9 % 80.3 %
2023 March 0.70 1,375 0.221 2 0 0.179 19.0 %
2023 February 0.07 422 0.228 0 0 0.054 76.3 %
2023 January 1.29 0 0.225 185 0.072 0 68.0 %
2022 December 0.83 46,471 0.189 73 40,513 0.182 61 12 12.8 % 3.7 %
2022 September 11.33 25,340 0.099 20 23,404 0.105 20 0 7.6 % -6.1 %
2022 August 8.85 27,231 0.148 33 22,255 0.162 30 3 18.3 % -9.5 %
2022 July 5.24 0 0.100 0 0.030 70.0 %
Totals 37.99 109,113 2.025 146 96,274 0.942 114 30 -3.7 % 46.3 %

Total Suspended Solids (TSS)

BSTF Pollutant Load Reduction Report for "Total Suspended Solids (TSS)"
Year / Month Rainfall In (Wet well / Pump A) Out (Wet well / Pump B) Reduction Goal Percent Volume
Lost		 Percent TSS
Reduction
SARASOTA_ARMS - AL-1 (in) Volume (kgals) TSS conc. (mg/l) TSS load (lbs) Volume (kgals) TSS conc. (mg/l) TSS load (lbs) TSS (lbs) TSS (lbs)
2023 June 6.63 2,733 32.900 750 2,321 4.670 90 660 15.1 % 85.8 %
2023 May 0.69 2,819 31.000 729 2,399 10.000 200 529 14.9 % 67.7 %
2023 April 2.36 2,722 54.000 1,226 5,197 14.000 607 619 -90.9 % 74.1 %
2023 March 0.70 1,375 28.000 321 0 7.500 73.2 %
2023 February 0.07 422 15.000 52 0 9.600 36.0 %
2023 January 1.29 0 15.200 185 6.000 9 60.5 %
2022 December 0.83 46,471 26.000 10,083 40,513 18.000 6,085 3,998 12.8 % 30.8 %
2022 September 11.33 25,340 18.000 3,806 23,404 3.600 703 3,103 7.6 % 80.0 %
2022 August 8.85 27,231 26.000 5,908 22,255 16.000 2,971 2,937 18.3 % 38.5 %
2022 July 5.24 0 88.000 0 40.000 54.5 %
Totals 37.99 109,113 334.100 22,875 96,274 129.370 10,665 11,846 -3.7 % 60.1 %