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Line 39: + + + + + + + − <h5>Sizing Stone Reservoirs</h5> − The following calculation is used to size the stone storage bed (reservoir) used as a base course for designs without underdrains. It is assumed that the footprint of the stone bed will be equal to the footprint of the pavement. The following equations are taken from the ICPI Manual <ref>Smith, D. 2006. Permeable Interlocking Concrete Pavements; Selection, Design, − Construction, Maintenance. 3rd Edition. Interlocking Concrete Pavement Institute. − Burlington, ON.</ref> − The equation for the depth of the stone bed is as follows: − − <math>db= [Qc\times R + P - i\times T ] / V</math> − where:{{plainlist|}} − *''db'' = Stone bed depth (m) − *''Qc'' = Depth of runoff from contributing drainage area, not including permeable paving surface(m) − *''R'' = Ac/Ap = Ratio of contributing drainage area (Ac) to permeable paving area (Ap) − *''P'' = Rainfall depth (m) − *''i'' = Infiltration rate for native soils (m/day) − *''T'' = Time to fill stone bed (typically 2 hr) − *''Vr'' = Void ratio for stone bed (typically 0.4 for 50 mm dia. stone) − − Note that the contributing drainage area (Ac) should not contain pervious areas. − For designs that include an underdrain, the maximum depth of the stone reservoir below the invert of the underdrain pipe can be calculated as follows: − <math>dr_{max} = [i \times ts] / Vr </math> − Where: − {{plainlist|}} − *''dr<sub>max'' = Maximum stone reservoir depth (m) − *''i'' = Infiltration rate for native soils (m/hr) − *''Vr'' = Void space ratio for aggregate used (typically 0.4 for 50 mm clear stone) − *''ts'' = Time to drain (design for 48 hour time to drain is recommended) − − The value for native soil infiltration rate (i) used in the above equations should be the design infiltration rate that incorporates a safety correction factor based on the ratio of the mean value at the proposed bottom elevation of the practice to the mean value in the least permeable soil horizon within 1.5 metres of the proposed bottom elevation − On highly permeable soils (e.g., infiltration rate of 45 mm/hr or greater), a maximum stone reservoir depth of 2 metres is recommended to prevent soil compaction and loss of permeability from the mass of overlying stone and stored water. − If trying to size the area of permeable paving based on the contributing drainage area, the following equation may be used: − − <math>Ap= [Qc \times Ac] / [Vr \times dp – P + i \times T] </math> − Geotextiles can be used to prevent downward migration of smaller particles in to larger aggregates, and slump of heavier particles into finer underlying courses. The formation of biofilm on geotextiles has also been shown to improve water quality: + − *By degrading petroleum hydrocarbons<ref>Newman AP, Coupe SJ, Spicer GE, Lynch D, Robinson K. MAINTENANCE OF OIL-DEGRADING PERMEABLE PAVEMENTS: MICROBES, NUTRIENTS AND LONG-TERM WATER QUALITY PROVISION. https://www.icpi.org/sites/default/files/techpapers/1309.pdf. Accessed July 17, 2017</ref> − *By reducing organic pollutant and nutrient concentrations<ref>Paul P, Tota-Maharaj K. Laboratory Studies on Granular Filters and Their Relationship to Geotextiles for Stormwater Pollutant Reduction. Water. 2015;7(4):1595-1609. doi:10.3390/w7041595.</ref> − *When installing geotextiles an overlap of 150 - 300 mm should be used. − Material specifications should conform to OPSS 1860 for Class II geotextile fabrics<ref>ONTARIO PROVINCIAL STANDARD SPECIFICATION METRIC OPSS 1860 MATERIAL SPECIFICATION FOR GEOTEXTILES. 2012. http://www.raqsb.mto.gov.on.ca/techpubs/OPS.nsf/0/2ccb9847eb6c56738525808200628de1/$FILE/OPSS%201860%20Apr12.pdf. Accessed July 17, 2017</ref> − *Fabrics should be woven monofilament or non-woven needle punched. − *Woven slit film and non-woven heat bonded fabrics should not be used, as they are prone to clogging. − In choosing a product, consider: − {{plainlist|}} − *''The maximum forces that will be exerted on the fabric (i.e., what tensile, tear and puncture strength ratings are required?)'', − *''The load bearing ratio of the underlying native soil (i.e. is the geotextile needed to prevent downward migration of aggregate into the native soil?)'', − *''The texture (i.e., grain size distribution) of the overlying and underlying materials, and'' − *''The suitable apparent opening size (AOS) for non-woven fabrics, or percent open area (POA) for woven fabrics, to maintain water flow even with sediment and microbial film build-up''
→Design
<h3>Modeling permeable paving in the Treatment Train Tool</h3>
<h3>Modeling permeable paving in the Treatment Train Tool</h3>
'''[[Permeable paving: TTT]]'''
'''[[Permeable paving: TTT]]'''
<h3>Sizing Stone Reservoirs</h3>
[[Permeable paving: Sizing and modeling]]
<h3>Materials</h3>
<h3>Materials</h3>
<h4>Proprietary blocks</h4>
<h4>Cast in place</h4>
<h4>Stone Reservoir</h4>
<h4>Stone Reservoir</h4>
The stone reservoir must meet both runoff storage and structural support requirements.
The stone reservoir must meet both runoff storage and structural support requirements.
The bottom of the reservoir should be level so that water infiltrates evenly. If the system is not designed for infiltration, the bottom should slope at 1 - 5% toward the underdrain.
The bottom of the reservoir should be level so that water infiltrates evenly. If the system is not designed for infiltration, the bottom should slope at 1 - 5% toward the underdrain.
{{:Gravel}}
{{:Gravel}}
<h4>Geotextile</h4>
<h4>Geotextile</h4>
{{:Geotextiles}}
==Performance==
==Performance==