Permeable pavements: Performance

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TSS Reduction[edit]

TSS - permeable pavement.JPG

The performance results for Permeable pavement/Porous Asphalt: Life Cycle Costs practices, located within TRCA's watershed originate from three primary sites:

  • Kortright Centre Parking Lot
  • Seneca College
  • IMAX Corporation, head office

The mean performance value recorded at the outlet for Permeable Pavement practices' ability to remove Total Suspended Sediments (TSS) was was calculated based on 296 separate recordings between 2005-2007, and 2010-2017 amongst the three sites previously mentioned.

As can be seen in the corresponding boxplot the mean performance removal efficiency of the permeable pavement practices monitored are well below the suggested guideline of 30 mg/L (Canadian Water Quality Guideline (CWQG), or (background (assumed at <5 mg/L)+ 25 mg/L for short term (<24 hour) exposure) (CCME, 2002[1]; (TRCA, 2021[2]).

The median value of the 301 samples taken was 8.95 mg/L whereas the mean was 17.10 mg/L, with a 12% guideline exceedance.

TP - permeable pavement.JPG

Phosphorus Reduction[edit]

The performance results for Permeable pavement/Porous Asphalt: Life Cycle Costs practices, located within TRCA's watershed originate from three primary sites:

  • Kortright Centre Parking Lot
  • Seneca College
  • IMAX Corporation, head office

The mean performance value recorded at the outlet for Permeable Pavement practices' ability to remove Total Phosphorus (TP) was calculated based on 300 separate recordings between 2005-2007, and 2010-2017 amongst the three sites previously mentioned.

As can be seen in the corresponding boxplot, the mean performance removal efficiency of the bioretention practices monitored are not meeting the acceptable upper extent range of nutrients as of 0.03 mg/L (30 µg/L) (Environment Canada, 2004[3]; OMOEE, 1994[4]).

The median value of the 355 samples taken was 0.04 mg/L whereas the mean was 0.08 mg/L, with a 62% guideline exceedance. Given the age of most of these practices, more inspection, maintenance and necessary rehabilitation will be needed to ensure they are able to meet the federal and provincial governments' guideline requirement for stormwater quality.

Please refer to the Phosphorus page and the additives page for more information on how LIDs can reduce contaminant loading in stormwater

Recent Performance Research[edit]

Shown here are the two variations of hydrodynamic separators (Oil and grit separators) used in the 6-year study conducted by Lee, et al., 2014. All four OGS' used were of different sizes. The first (Type A) was a dip cylindrical plate with a centershaft and the second (Type B) was a hollow cylindrical screen. All four sites where the OGS' were installed were in urban settings in Gyunggi Province, Korea, and discharge into Gyung-An stream, which deposits into the Pal-dang Lake. This lake is the the primary drinking water source for Seoul's Metropolitan area (Lee, et al. 2014[5]

.

  • (Clary et al., 2020) - International Stormwater BMP Database: 2020 Summary Statistics.
    • The International Stormwater Best Management Practices (BMP) Database is a publicly accessible repository for BMP performance monitoring study, design, and cost information. As of December 2019, the BMP Database contains data sets collected over four decades from over 700 BMP studies through the U.S., Canada, Sweden, New Zealand, Australia, China, etc. that are accessible on the project website ([www.bmpdatabase.org]). The performance data for both TSS and TP are as follows within the report:
      • Median TSS value of outflow/effluent of stormwater from P.P is 22 mg/L in comparison to 77 mg/L influent levels. These levels are computed using the BCa bootstrap method described by Efron and Tibishirani (1993). This value is below the required CCME levels for TSS in stormwater.
      • Median Total phosphorus (TP) value of outflow/effluent of stormwater from P.P is 0.10 mg/L in comparison to 0.17 mg/L influent levels. These levels are computed using the BCa bootstrap method described by Efron and Tibishirani (1993). This value is below the required CCME levels for TP in stormwater.

[6]).

  • (Lee, et al. 2014) - Performance evaluation and a sizing method for hydrodynamic separators treating urban stormwater runoff.
    • This study conducted performance monitoring over a 6-year period (137 separate storm events) of four different hydrodynamic separators in Korean urban catchments between 2006 - 2012. Removal rates were relatively low at all four sites (1. Roadway site: Avg. Inflow = 239.32 mg/L vs Avg. Outflow = 122.2- mg/L / 2. Residential site: Avg. Inflow = 59.74 mg/L vs Avg. Outflow = 50.35 mg/L / 3. Roadway Site: Avg. Inflow = 62.50 mg/L vs. Avg. Outflow = 33.76 mg/L / 4. Residential(63.5%) & Roadway (36.5%) CDA site: Avg. Inflow = 236.24 mg/L vs. Avg. Outflow = 160.54 mg/L). The low removal rates were due to high rates of extreme overflow events occurring with most suspended sediment being quite small/fine in nature (<75μm)(Lee, et al. 2014[8].

References[edit]

  1. Canadian Council of Ministers of the Environment (CCME). 2002. Canadian water quality guidelines for the protection of aquatic life: Total particulate matter. In: Canadian Environmental Quality Guidelines, Canadian Council of Ministers of the Environment, Winnipeg
  2. TRCA. 2021. Spatial Patterns (2016-2020) and Temporal Trends (1966-2020) in Stream Water Quality across TRCA’s Jurisdiction Prepared by Watershed Planning and Ecosystem Science. https://trcaca.s3.ca-central-1.amazonaws.com/app/uploads/2021/10/29113334/2016-2020-SWQ-Report-v11_FINAL_AODA-FA.pdf
  3. Environment Canada. (2004). Canadian guidance framework for the management of phosphorus in freshwater systems. Ecosystem Health: Science‐based solutions report no. 1–8. Cat. No. En1–34/8–2004E.
  4. Ontario Ministry of Environment and Energy (OMOEE), 1994. Policies, Guidelines and Provincial Water Quality Objectives of the Ministry of Environment and Energy. Queen’s Printer for Ontario. Toronto, ON.
  5. Lee, D.H., Min, K.S. and Kang, J.H., 2014. Performance evaluation and a sizing method for hydrodynamic separators treating urban stormwater runoff. Water science and technology, 69(10), pp.2122-2131)
  6. Clary, J., Jones, J., Leisenring, M., Hobson, P. and Strecker, E. 2020. International stormwater BMP database 2020 summary statistics. Water Environment & Reuse Foundation.
  7. Jianghua, Y., Qitao, Y. and Kim, Y. 2009. Performance analysis of a hydrodynamic separator for treating particulate pollutants in highway rainfall runoff. Environmental Engineering Research, 14(4), pp.262-269. https://www.eeer.org/upload/eer-14-4-262-.pdf
  8. Lee, D.H., Min, K.S. and Kang, J.H., 2014. Performance evaluation and a sizing method for hydrodynamic separators treating urban stormwater runoff. Water science and technology, 69(10), pp.2122-2131)