Journal of Environmental Management 139 (2014) 69e79
Contents lists available at ScienceDirect
Journal of Environmental Management journal homepage: www.elsevier.com/locate/jenvman
Stormwater quality of springesummer-fall effluent from three partial-infiltration permeable pavement systems and conventional asphalt pavement Jennifer Drake a, *, Andrea Bradford b, Tim Van Seters c a b c
Department of Civil Engineering, University of Toronto, 35 St. George St., Toronto, ON, Canada M5S 1A4 School of Engineering, University of Guelph, 50 Stone Rd., Guelph, ON, Canada N1G 2W Sustainable Technologies Evaluation Program, Toronto and Region Conservation, 9550 Pine Valley Drive, Vaughan, ON, Canada L41 1A6
a r t i c l e i n f o
a b s t r a c t
Article history: Received 24 July 2013 Received in revised form 13 November 2013 Accepted 22 November 2013 Available online 27 March 2014
This study examined the spring, summer and fall water quality performance of three partial-infiltration permeable pavement (PP) systems and a conventional asphalt pavement in Ontario. The study, conducted between 2010 and 2012, compared the water quality of effluent from two Interlocking Permeable Concrete Pavements (AquaPaveÒ and Eco-OptilocÒ) and a HydromediaÒ Pervious Concrete pavement with runoff from an Asphalt control pavement. The usage of permeable pavements can mitigate the impact of urbanization on receiving surface water systems through quantity control and stormwater treatment. The PP systems provided excellent stormwater treatment for petroleum hydrocarbons, total suspended solids, metals (copper, iron, manganese and zinc) and nutrients (total-nitrogen and totalphosphorus) by reducing event mean concentrations (EMC) as well as total pollutant loadings. The PPs significantly reduced the concentration and loading of ammonia (NHþ 4 þ NH3 ), nitrite (NO2 ) and organic-nitrogen (Org-N) but increased the concentration and loading of nitrate (NO 3 ). The PP systems had mixed performances for the treatment of phosphate (PO3 4 ). The PP systems increased the concentration of sodium (Na) and chloride (Cl) but EMCs remained well below recommended levels for drinking water quality. Relative to the observed runoff, winter road salt was released more slowly from the PP systems resulting in elevated spring and early-summer Cl and Na concentrations in effluent. PP materials were found to introduce dissolved solids into the infiltrating stormwater. The release of these pollutants was verified by additional laboratory scale testing of the individual pavement and aggregate materials at the University of Guelph. Pollutant concentrations were greatest during the first few months after construction and declined rapidly over the course of the study. Ó 2014 Elsevier Ltd. All rights reserved.
Keywords: Permeable pavement Stormwater quality Low permeability soil Pollutant removal Cold climate Seasonal performance
1. Introduction Permeable pavements (PP) allow for the treatment and management of stormwater near to its source. PP systems reduce the total pollutant mass delivered to receiving systems by capturing pollutants within the pavement system and removing them from stormwater (Bean et al., 2007). In partial-infiltration systems, a significant proportion of stormwater will infiltrate into native soils while some excess stormwater is discharged to a receiving surface water system by way of underdrains. Outflow from an underdrained PP system is not considered runoff and is referred to as * Corresponding author. Tel.: þ1 416 978 8248. E-mail addresses: [email protected] (J. Drake), [email protected] (A. Bradford). http://dx.doi.org/10.1016/j.jenvman.2013.11.056 0301-4797/Ó 2014 Elsevier Ltd. All rights reserved.
exfiltrated stormwater or effluent (Bean et al., 2007; Roseen et al., 2012). Particulates within stormwater are captured by mechanical filtration through the PP surface and base layers. As water migrates through the PP additional treatment is possible through adsorption, transformation, biological degradation and volatization. Numerous researchers (Rushton, 2001; Brattebo and Booth, 2003; Bean et al., 2007; Toronto and Region Conservation Authority, 2008; Roseen et al., 2009; Fassman and Blackbourn, 2010) have observed that PP effluent has lower suspended solids and heavy metal (e.g. Pb, Zn, Cu, Cd and Fe) concentrations than runoff from traditional asphalt pavements. Legret and Colandini (1999) reported that, relative to a reference catchment, runoff from a porous asphalt pavement reduced the loading of suspended sediments, Pd, Cd and Zn by 59%, 84%, 77% and 73% respectively to downstream systems. Rushton (2001) evaluated the annual loads
70
J. Drake et al. / Journal of Environmental Management 139 (2014) 69e79
Fig. 1. Study site schematic.
from runoff from two PP-to-swale systems. Relative to a traditional asphalt pavement, the PP and swale reduced TSS, and heavy metal (Fe, Pb, Mn and Zn) loads. The PP system was particularly effective at capturing solids and metals as removal rates for these pollutants ranged between 75% and 94%. Fassman and Blackbourn (2010) observed 70% reduction in total suspended solids and Cu loads and a 96% reduction in total Zn loads from sampled storms. Long term studies, such as Brattebo and Booth (2003), have noted that PP systems can continue to improve stormwater quality even after several years of use. Effluent quality, however, does change with time which can result in both positive and negative changes in performance. The capacity for pollutant removal over time and the possibility of remobilization have important implications for sustained benefits of PP systems as well as the potential contamination of groundwater systems. PP exfiltrate has been consistently shown to have a pH ranging between 8 and 9.5 (Pratt et al., 1995; Sansalone and Teng, 2004; Kwiatkowski et al., 2007; TRCA, 2008) whereas rainfall and asphalt
runoff tend to be more acidic. For the protection of aquatic life, common water quality guidelines recommend that pH should be maintained between 6.5 and 8.5 (MOE, 1994) so PP effluent sometimes fails to meet this guideline. Monitoring studies conducted by Roseen et al. (2009) and TRCA (2008) have observed that PP effluent contains low or non-detectable concentrations of petroleum-based hydrocarbons. Nutrient concentrations in PP effluent have been addressed in several studies (Bean et al., 2007; Roseen et al., 2009; Collins et al., 2010; Tota-Maharaj and Scholz, 2010). Collins et al. (2010) reported that PP exfiltrate had consistently lower TKN and NHþ 4 concentrations and higher NO concentrations than asphalt runoff indicating 3 occurrence of nitrification (NHþ 4 / NO3 ). As a filtering system, PP can capture particulate-bound P leading to reductions in TP concentrations. Although several studies (Bean et al., 2007; TRCA, 2008; Roseen et al., 2009; Tota-Maharaj and Scholz, 2010) have noted that PP effluent has reduced TP levels, the long-term retention of nutrients has not yet been demonstrated.
Fig. 2. Profile of permeable interlocking concrete pavers.
J. Drake et al. / Journal of Environmental Management 139 (2014) 69e79
71
Fig. 3. Profile of pervious concrete.
To fully understand the environmental impact of partialinfiltration PP systems more information is needed regarding stormwater quality of effluent. In cold climates, like Ontario, a distinction between the winter season and other times of the year is needed to interpret water quality performance data. Roseen et al. (2009) evaluated the seasonal performance of numerous low impact development technologies including porous asphalt and concluded that LID have a higher level of functionality during winter months. The objective of this study is to compare overall stormwater quality of PP effluent from three partial-infiltration PP systems and asphalt runoff throughout spring-summer-fall (warm) season. The stormwater quality of permeable interlocking concrete pavement (PICP) and pervious concrete effluent will be examined and trade-offs between the two systems will be discussed. Stormwater quality is evaluated for general quality, petroleum-based hydrocarbons, nutrients and metals. The results of this study demonstrate the environmental benefits of partial-infiltration PP systems in the context of stormwater quality.
the north and south sides of the parking lot and approximately half of the berm area slopes towards the pavement. Each PP cell is drained by a 100 mm diameter Big O perforated tubing placed at the base of an aggregate trench at the interface between the aggregate reservoir and the native soil. The ASH cell is drained via a catchbasin. Infiltrated stormwater collected from each PP cell is conveyed separately in sealed pipes to a downstream
Table 1 Stormwater quality parameters, minimum detection limits and water quality guidelines. Pollutant
Units
MDLa
Max level
Sourcea
500 Variable 120 (long-term), 640 (short-term) 200 8.5
CWQG CEQG CEQG
75 200 0.5 5 300 5 50
PWQO-Interim PWQO PWQO-Interim PWQO-Interim PWQO PWQO-Interim CWQG
20
PWQO-Interim
0.02 3.2 45
PWQO CWQG CWQG
0.03
PWQO-Interim
Variable
PWQO
General quality DS TSS Cl
mg/L mg/L mg/L
2. Methodology
Na pH
mg/L e
0.04 5
2.1. Site design
Metals Al B Cd Cu Fe Pb Mn K Sr Zn
mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L
1 10 0.5 5 30 0.5 0.01 0.06 1 20
Nutrients NH4þ þ NH3 NOL 2 NOL 3 org-N TN PO3 4 TP
mg/L mg/L mg/L mg/L mg/L mg/L mg/L
The PP parking lot is located at the Kortright Centre for Conservation in Vaughan, Ontario. Constructed over the fall of 2009 and the spring of 2010 the facility consists of four pavement cells which are 230e233 m2 in size and have a capacity for 8e10 parked vehicles in each cell (Fig. 1). Two cells are constructed with PICP; AquaPaveÒ (AP) and Eco-OptilocÒ (EO), one cell is constructed with HydromediaÒ; Pervious Concrete (PC) supplied by Lafarge and one cell is constructed with traditional asphalt (ASH). The pavement cells are separated by a raised concrete curb which extends below the surface to the native soils preventing the cross-flow of stormwater. Aggregate reservoirs below the PP (Figs. 2 and 3) are constructed with two layers of 19 mm and 60 mm diameter clear stone providing a combined depth of at least 40 cm. The EO pavement has joints which are 13e14 cm wide and uses high performance bedding (HPB) as joint and bedding material (diameter w1e9 mm) while the AP pavement has joints which are 3e4 cm wide and uses HPB as bedding and Engineered Joint Stabilizer (diameter w2e 3 mm) as joint material. The AP pavement also includes an InbitexÒ geotextile placed between the bedding and aggregate layers. Vegetated berms approximately 5e6 m wide with mature trees line
Guideline
50 2.5 1
0.01 0.02 0.005 0.09 0.11 0.0025 0.01
Petroleum based hydrocarbons Solvent extractable mg/L 1 PAHs ng/L e a
CWQG PWQO
Acronyms: Minimum detection limit (MDL), Provincial water quality objective (PWQO), Canadian water quality guideline (CWQG), Canadian environmental quality guideline (CEQG).
72
J. Drake et al. / Journal of Environmental Management 139 (2014) 69e79
Table 2 General quality concentration and mass loading results. Pollutant
DS
TSS
Cl
Na
pH
Pavement
ASH AP EO PC ASH AP EO PC ASH AP EO PC ASH AP EO PC ASH AP EO PC
Concentrations (mg/L)
Loadings (kg/ha)
Range
x
~ x
s
RE
Range
x
~ x
s
SOL
Contents lists available at ScienceDirect
Journal of Environmental Management journal homepage: www.elsevier.com/locate/jenvman
Stormwater quality of springesummer-fall effluent from three partial-infiltration permeable pavement systems and conventional asphalt pavement Jennifer Drake a, *, Andrea Bradford b, Tim Van Seters c a b c
Department of Civil Engineering, University of Toronto, 35 St. George St., Toronto, ON, Canada M5S 1A4 School of Engineering, University of Guelph, 50 Stone Rd., Guelph, ON, Canada N1G 2W Sustainable Technologies Evaluation Program, Toronto and Region Conservation, 9550 Pine Valley Drive, Vaughan, ON, Canada L41 1A6
a r t i c l e i n f o
a b s t r a c t
Article history: Received 24 July 2013 Received in revised form 13 November 2013 Accepted 22 November 2013 Available online 27 March 2014
This study examined the spring, summer and fall water quality performance of three partial-infiltration permeable pavement (PP) systems and a conventional asphalt pavement in Ontario. The study, conducted between 2010 and 2012, compared the water quality of effluent from two Interlocking Permeable Concrete Pavements (AquaPaveÒ and Eco-OptilocÒ) and a HydromediaÒ Pervious Concrete pavement with runoff from an Asphalt control pavement. The usage of permeable pavements can mitigate the impact of urbanization on receiving surface water systems through quantity control and stormwater treatment. The PP systems provided excellent stormwater treatment for petroleum hydrocarbons, total suspended solids, metals (copper, iron, manganese and zinc) and nutrients (total-nitrogen and totalphosphorus) by reducing event mean concentrations (EMC) as well as total pollutant loadings. The PPs significantly reduced the concentration and loading of ammonia (NHþ 4 þ NH3 ), nitrite (NO2 ) and organic-nitrogen (Org-N) but increased the concentration and loading of nitrate (NO 3 ). The PP systems had mixed performances for the treatment of phosphate (PO3 4 ). The PP systems increased the concentration of sodium (Na) and chloride (Cl) but EMCs remained well below recommended levels for drinking water quality. Relative to the observed runoff, winter road salt was released more slowly from the PP systems resulting in elevated spring and early-summer Cl and Na concentrations in effluent. PP materials were found to introduce dissolved solids into the infiltrating stormwater. The release of these pollutants was verified by additional laboratory scale testing of the individual pavement and aggregate materials at the University of Guelph. Pollutant concentrations were greatest during the first few months after construction and declined rapidly over the course of the study. Ó 2014 Elsevier Ltd. All rights reserved.
Keywords: Permeable pavement Stormwater quality Low permeability soil Pollutant removal Cold climate Seasonal performance
1. Introduction Permeable pavements (PP) allow for the treatment and management of stormwater near to its source. PP systems reduce the total pollutant mass delivered to receiving systems by capturing pollutants within the pavement system and removing them from stormwater (Bean et al., 2007). In partial-infiltration systems, a significant proportion of stormwater will infiltrate into native soils while some excess stormwater is discharged to a receiving surface water system by way of underdrains. Outflow from an underdrained PP system is not considered runoff and is referred to as * Corresponding author. Tel.: þ1 416 978 8248. E-mail addresses: [email protected] (J. Drake), [email protected] (A. Bradford). http://dx.doi.org/10.1016/j.jenvman.2013.11.056 0301-4797/Ó 2014 Elsevier Ltd. All rights reserved.
exfiltrated stormwater or effluent (Bean et al., 2007; Roseen et al., 2012). Particulates within stormwater are captured by mechanical filtration through the PP surface and base layers. As water migrates through the PP additional treatment is possible through adsorption, transformation, biological degradation and volatization. Numerous researchers (Rushton, 2001; Brattebo and Booth, 2003; Bean et al., 2007; Toronto and Region Conservation Authority, 2008; Roseen et al., 2009; Fassman and Blackbourn, 2010) have observed that PP effluent has lower suspended solids and heavy metal (e.g. Pb, Zn, Cu, Cd and Fe) concentrations than runoff from traditional asphalt pavements. Legret and Colandini (1999) reported that, relative to a reference catchment, runoff from a porous asphalt pavement reduced the loading of suspended sediments, Pd, Cd and Zn by 59%, 84%, 77% and 73% respectively to downstream systems. Rushton (2001) evaluated the annual loads
70
J. Drake et al. / Journal of Environmental Management 139 (2014) 69e79
Fig. 1. Study site schematic.
from runoff from two PP-to-swale systems. Relative to a traditional asphalt pavement, the PP and swale reduced TSS, and heavy metal (Fe, Pb, Mn and Zn) loads. The PP system was particularly effective at capturing solids and metals as removal rates for these pollutants ranged between 75% and 94%. Fassman and Blackbourn (2010) observed 70% reduction in total suspended solids and Cu loads and a 96% reduction in total Zn loads from sampled storms. Long term studies, such as Brattebo and Booth (2003), have noted that PP systems can continue to improve stormwater quality even after several years of use. Effluent quality, however, does change with time which can result in both positive and negative changes in performance. The capacity for pollutant removal over time and the possibility of remobilization have important implications for sustained benefits of PP systems as well as the potential contamination of groundwater systems. PP exfiltrate has been consistently shown to have a pH ranging between 8 and 9.5 (Pratt et al., 1995; Sansalone and Teng, 2004; Kwiatkowski et al., 2007; TRCA, 2008) whereas rainfall and asphalt
runoff tend to be more acidic. For the protection of aquatic life, common water quality guidelines recommend that pH should be maintained between 6.5 and 8.5 (MOE, 1994) so PP effluent sometimes fails to meet this guideline. Monitoring studies conducted by Roseen et al. (2009) and TRCA (2008) have observed that PP effluent contains low or non-detectable concentrations of petroleum-based hydrocarbons. Nutrient concentrations in PP effluent have been addressed in several studies (Bean et al., 2007; Roseen et al., 2009; Collins et al., 2010; Tota-Maharaj and Scholz, 2010). Collins et al. (2010) reported that PP exfiltrate had consistently lower TKN and NHþ 4 concentrations and higher NO concentrations than asphalt runoff indicating 3 occurrence of nitrification (NHþ 4 / NO3 ). As a filtering system, PP can capture particulate-bound P leading to reductions in TP concentrations. Although several studies (Bean et al., 2007; TRCA, 2008; Roseen et al., 2009; Tota-Maharaj and Scholz, 2010) have noted that PP effluent has reduced TP levels, the long-term retention of nutrients has not yet been demonstrated.
Fig. 2. Profile of permeable interlocking concrete pavers.
J. Drake et al. / Journal of Environmental Management 139 (2014) 69e79
71
Fig. 3. Profile of pervious concrete.
To fully understand the environmental impact of partialinfiltration PP systems more information is needed regarding stormwater quality of effluent. In cold climates, like Ontario, a distinction between the winter season and other times of the year is needed to interpret water quality performance data. Roseen et al. (2009) evaluated the seasonal performance of numerous low impact development technologies including porous asphalt and concluded that LID have a higher level of functionality during winter months. The objective of this study is to compare overall stormwater quality of PP effluent from three partial-infiltration PP systems and asphalt runoff throughout spring-summer-fall (warm) season. The stormwater quality of permeable interlocking concrete pavement (PICP) and pervious concrete effluent will be examined and trade-offs between the two systems will be discussed. Stormwater quality is evaluated for general quality, petroleum-based hydrocarbons, nutrients and metals. The results of this study demonstrate the environmental benefits of partial-infiltration PP systems in the context of stormwater quality.
the north and south sides of the parking lot and approximately half of the berm area slopes towards the pavement. Each PP cell is drained by a 100 mm diameter Big O perforated tubing placed at the base of an aggregate trench at the interface between the aggregate reservoir and the native soil. The ASH cell is drained via a catchbasin. Infiltrated stormwater collected from each PP cell is conveyed separately in sealed pipes to a downstream
Table 1 Stormwater quality parameters, minimum detection limits and water quality guidelines. Pollutant
Units
MDLa
Max level
Sourcea
500 Variable 120 (long-term), 640 (short-term) 200 8.5
CWQG CEQG CEQG
75 200 0.5 5 300 5 50
PWQO-Interim PWQO PWQO-Interim PWQO-Interim PWQO PWQO-Interim CWQG
20
PWQO-Interim
0.02 3.2 45
PWQO CWQG CWQG
0.03
PWQO-Interim
Variable
PWQO
General quality DS TSS Cl
mg/L mg/L mg/L
2. Methodology
Na pH
mg/L e
0.04 5
2.1. Site design
Metals Al B Cd Cu Fe Pb Mn K Sr Zn
mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L
1 10 0.5 5 30 0.5 0.01 0.06 1 20
Nutrients NH4þ þ NH3 NOL 2 NOL 3 org-N TN PO3 4 TP
mg/L mg/L mg/L mg/L mg/L mg/L mg/L
The PP parking lot is located at the Kortright Centre for Conservation in Vaughan, Ontario. Constructed over the fall of 2009 and the spring of 2010 the facility consists of four pavement cells which are 230e233 m2 in size and have a capacity for 8e10 parked vehicles in each cell (Fig. 1). Two cells are constructed with PICP; AquaPaveÒ (AP) and Eco-OptilocÒ (EO), one cell is constructed with HydromediaÒ; Pervious Concrete (PC) supplied by Lafarge and one cell is constructed with traditional asphalt (ASH). The pavement cells are separated by a raised concrete curb which extends below the surface to the native soils preventing the cross-flow of stormwater. Aggregate reservoirs below the PP (Figs. 2 and 3) are constructed with two layers of 19 mm and 60 mm diameter clear stone providing a combined depth of at least 40 cm. The EO pavement has joints which are 13e14 cm wide and uses high performance bedding (HPB) as joint and bedding material (diameter w1e9 mm) while the AP pavement has joints which are 3e4 cm wide and uses HPB as bedding and Engineered Joint Stabilizer (diameter w2e 3 mm) as joint material. The AP pavement also includes an InbitexÒ geotextile placed between the bedding and aggregate layers. Vegetated berms approximately 5e6 m wide with mature trees line
Guideline
50 2.5 1
0.01 0.02 0.005 0.09 0.11 0.0025 0.01
Petroleum based hydrocarbons Solvent extractable mg/L 1 PAHs ng/L e a
CWQG PWQO
Acronyms: Minimum detection limit (MDL), Provincial water quality objective (PWQO), Canadian water quality guideline (CWQG), Canadian environmental quality guideline (CEQG).
72
J. Drake et al. / Journal of Environmental Management 139 (2014) 69e79
Table 2 General quality concentration and mass loading results. Pollutant
DS
TSS
Cl
Na
pH
Pavement
ASH AP EO PC ASH AP EO PC ASH AP EO PC ASH AP EO PC ASH AP EO PC
Concentrations (mg/L)
Loadings (kg/ha)
Range
x
~ x
s
RE
Range
x
~ x
s
SOL
