B805 TEMPORARY EROSION AND SEDIMENT CONTROL MEASURES - OPSS 805

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Jack Neal
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1 B805 MEASURES - OPSS GENERAL Construction activities frequently remove protective cover and expose soil to accelerated rates of erosion. Sediments generated thereby can be conveyed via runoff and channelized flow to impact sensitive receiving waters or other environmentally sensitive areas. Temporary erosion and sediment control measures are warranted on contracts which call for grading, drainage and other work that will disturb the earth surface. Measures shall be employed to minimize erosion and to remove sediments from water flowing from the construction site in order to meet environmental legislative requirements. OPSS 805 does not identify all available erosion and sediment control measures which the designer may consider, however, it does address most of the temporary measures commonly used during construction. The specification provides a large number of options for specifying either generic or specific items. When generic items are specified, the specification is designed so that the contractor is given the option of choosing from amongst a variety of items. This permits the cost-effective selection of end result performance items. In addition, OPSS 805 addresses the management of erosion and sediment control items which includes the requirements for maintaining erosion and sediment control measures and the removal of accumulated sediments from behind such measures. Design guidance provided in this section is not intended to supercede detail design of temporary erosion and sediment controls. Information within this section is intended to assist in the design and estimating required for the preparation of the contract package. The following constraints should be observed when considering the use of tender items found within OPSS 805: For control of erosion on bare earth surfaces other than temporary control in areas of channelized flow, reference should be made to OPSS 804 Construction Specification for Seed and Cover. All temporary measures identified in OPSS 805 are intended for removal at the completion of the contract or when permanent erosion and sediment control measures are in place and functioning. Permanent erosion and sediment control measures are not covered by OPSS 805. The measures identified in OPSS 805 are intended for use only during normal spring, summer, and fall construction. Special measures not addressed by OPSS 805 may be required when permanent cover will not be established prior to winter shut down. January 2016 Page 1 of 10 B805

2 Winter construction may require special measures not addressed in OPSS 805. When identifying the location of rock flow check dams, the designer should consider their location and potential for an errant vehicle following the ditch line to impact rock flow check dams. A rock flow check dam presents a potential snagging point for an errant vehicle. Designers should try to locate rock flow check dams in roadside ditches as far from the traveled portion of the roadway as practical or where they will be located behind existing roadside barriers. Shielding of rock flow check dams should be considered as a last resort when the rock flow check dams need to be located where there is a high potential for impact Maintenance All temporary measures identified in OPSS 805 require inspection, maintenance and sediment removal to ensure that they function as intended. In selecting any temporary measures, consideration should be given to the length of time such measures shall be in place, the effectiveness of related erosion control measures such as seeding and cover specifications, resulting frequency of sediment removal and the removal of the measures at the end of the contract. The designer should consider the following factors when selecting temporary erosion and sediment control measures: Straw bales are intended for use over short periods of time to ensure protection during establishment of vegetative cover, and in conjunction with an operational constraint for a time limit (e.g. 45 days) for the placement of specified, permanent cover after the completion of grading. Placement of erosion and sediment control measures should always take into account the access needs for maintenance and final removal REFERENCES MTO Environmental Guide for Erosion and Sediment Control during Construction of Highway Projects HSB Provincial Engineering Memorandum , New Erosion and Sedimentation Control Program Design Policy TENDER ITEMS Unit of Measure - By Metre Light-Duty Sediment Barriers Light-Duty Straw Bale Barriers Light-Duty Silt Fence Barriers Light-Duty Fibre Roll Barriers January 2016 Page 2 of 10 B805

3 Heavy-Duty Sediment Barriers Heavy-Duty Silt Fence Barriers Heavy-Duty Wire-Backed Silt Fence Barriers Berm Barriers Sandbag Barriers Fibre Roll Grade Breaks Turbidity Curtains Unit of Measure - By Each Flow Check Dams Straw Bale Flow Check Dams Fibre Roll Flow Check Dams Sandbag Flow Check Dams Rock Flow Check Dams Sediment Traps Slope Drains Diversion Ditches Sediment Traps for Dewatering Filter Bags Cofferdams SPECIFICATIONS Details of the work are contained in OPSS SPECIAL PROVISIONS Refer to Chapter E of this Manual to review the applicable special provisions. The timing for installation and removal of measures is specified in SSP 805F STANDARD DRAWINGS Applicable Standard Drawings are contained in the 219 series of the Ontario Provincial Standards Drawings (OPSD) and Ministry of Transportation of Ontario Drawings (MTOD) DESIGN Three approaches to temporary erosion and sediment control are addressed by OPSS 805 including: January 2016 Page 3 of 10 B805

4 1) the use of mitigation measures that control erosion by slowing the velocity of water in channelized flow; 2) the use of mitigation measures that control sedimentation by ponding water from overland flow and allowing sediment to settle out; and 3) the use of mitigation measures that minimize damage from sediment release by isolating environmentally sensitive areas and work areas. Under each approach a number of items are available for selection by the designer through OPSS 805. Table 1 provides design criteria and limits of use for temporary erosion and sediment control measures addressed in OPSS 805. The MTO Environmental Guide for Erosion and Sediment Control during Construction of Highway Projects shall be consulted for more detailed guidance on selection and design of temporary erosion and sediment controls including development of Erosion and Sediment Control Plans when required Slowing Water to Control Erosion in Channelized Flow The following tender items are available in OPSS 805 to minimize and control erosion of bare earth surfaces in channels, ditches and swales until such time as the specified permanent protection is provided: Flow Check Dams Straw Bale Flow Check Dams Fibre Roll Flow Check Dams Sandbag Flow Check Dams Rock Flow Check Dams Ponding Water to Control Sediment OPSS 805 addresses two kinds of temporary sediment control measures to pond water: sediment barriers; and sediment traps. The following sediment barrier tender items are available in OPSS 805 to prevent sediment from entering concentrated flows found in swales, ditches, and watercourses, or from reaching other sensitive locations including private property: Light-Duty Sediment Barriers Light-Duty Straw Bale Barriers Light-Duty Silt Fence Barriers January 2016 Page 4 of 10 B805

5 Light-Duty Fibre Roll Barriers Heavy-Duty Sediment Barriers Heavy-Duty Silt Fence Barriers Heavy-Duty Wire Backed Silt Fence Barriers Berm Barriers Sandbag Barriers Fibre Roll Grade Breaks Sediment traps are designed to receive sediments and control the release of water by intercepting and ponding sediment-laden concentrated flows in ditches and channels or from dewatering operations. They are designed to hold water for sufficient duration for settling sediments. The following trap tender items are available in OPSS 805: Sediment Traps Sediment Traps for Dewatering Filter Bags Isolating Sensitive Areas and Work Areas OPSS 805 addresses the following situations where measures are required to isolate sensitive areas and work areas: where work must be done within a waterbody and sediments generated in the work area must be prevented from entering the adjacent waterbody; and where runoff or other water flowing from adjacent areas into the work area can cause erosion damage to the work area and result in the need for additional erosion and sediment control downstream of the work area. The following tender items are available in OPSS 805 to isolate in-water work areas to prevent the passage of sediments to the adjacent water body: Coffer Dams Turbidity Curtains Where runoff or other water can flow into or over the work area resulting in erosion and sediment damage, the following tender items are available in OPSS 805: Light-Duty Sediment Barriers Heavy-Duty Sediment Barriers Slope Drains Diversion Ditches January 2016 Page 5 of 10 B805

6 805.8 COMPUTATION Sources of Information The main sources for information are field investigations, drainage plans, grading plans, fisheries assessments, erosion and sediment overview risk assessments, the Regional Geotechnical Section and the Regional Environmental Section Method of Calculation All tender items in this specification are PQP and are measured in metres or by each. The quantity for items measured in metres is calculated following the alignment of the item and the contour of the ground. All elements, including the rock flow check dam, required for the construction of a sediment trap are included with the sediment trap tender item. All elements, including the barrier and rock flow check dam, required for the construction of a sediment trap for dewatering are included with the sediment trap for dewatering tender item. All elements, including the corrugated pipe, inlet and outlet end sections, sediment trap and berm barrier, required for the construction of a slope drain are included with the slope drain tender item. All elements required for the construction of diversion ditches, including the excavation of the ditch, flow check dams, and other applicable components, are included with the diversion ditch tender item. All elements required for the construction of berm barriers, including the berm material, geotextile, and other applicable components, are included with the berm barriers tender item. Removal of materials used in the construction of measures and sediment removal are paid under the appropriate tender item for the temporary measure involved. Sediment removal is part of the maintenance component of the work DOCUMENTATION Contract Drawings Show the location and, where applicable, the plan alignment of the following items. Include a reference to the appropriate OPSD number. In some cases, a drawing detail will be required to clearly show the requirements. January 2016 Page 6 of 10 B805

7 Light-Duty Straw Bale Barriers Light-Duty Silt Fence Barriers Light-Duty Fibre Roll Barriers Heavy-Duty Silt Fence Barriers Heavy-Duty Wire-Backed Silt Fence Barriers Sandbag Barriers Fibre Roll Grade Breaks Straw Bale Flow Check Dams Fibre Roll Flow Check Dams Sandbag Flow Check Dams Rock Flow Check Dams Sediment Traps Slope Drains Sediment Traps for Dewatering Turbidity Curtains With the OPSD reference, show applicable dimensional information, as follows: Light Duty Fibre Roll Barriers roll diameter, d Fibre Roll Grade Breaks - roll diameter, d Fibre Roll Flow Check Dams - roll diameter, d Sediment Traps - basin length, L m Slope Drains - pipe diameter, mm Sediment Traps for Dewatering - basin dimensions, L x L m Typical fibre roll diameters are 150, 200, and 300 mm. When a silt fence barrier is used for property delineation, a notation ( For Property Delineation ) shall be included under the OPSD reference. When the contract drawings do not include removal or new construction drawings, the above information may be included in table format on the location or typical section drawings. There is no OPSD for the cofferdams, filter bags, diversion ditches, and berm barriers items. The work required for these items shall be shown on a drawing detail. Details and components may include but not be limited to: Cofferdams - alignment, offset from waterbody Filter Bags - volume of water to be filtered, geotextile filtration opening size (FOS) Diversion Ditches - alignment, dimensions, erosion control blanket, check dams, riprap Berm Barriers - alignment, dimensions, geotextile, outlet, riprap January 2016 Page 7 of 10 B805

8 Quantity Sheets Record all items on the Quantities - Miscellaneous Sheets. Each tender item requires a separate column. Enter each separate installation on one line of the Q-sheet. Show the chainage and offset in the location column. For linear measured (metre) tender items, enter the calculated installation length. For items with each measure, enter the unit quantity 1 for each installation Documentation Accuracy Stations are recorded to the nearest metre. Offsets are recorded to the nearest 0.1 m. Quantity entries are recorded to the nearest metre Non-Standard Special Provisions Write project and item specific requirements in an NSSP using the standard format described in this manual. Topics that may require an NSSP are: a filter bag geotextile with different properties than those specified is required; the retention of riparian vegetation constraint must be relaxed; a different timing constraint for the protection of erodible stockpiles is required; changes to the earth layer compaction method. January 2016 Page 8 of 10 B805

9 TABLE 1 OPSS 805 Design Criteria and Limits for Temporary Erosion and Sediment Control Temporary Control Measure Catchment Area Flow Velocity Slowing Water to Control Erosion in Channelized Flow Channel Slope Barrier Length/Unit Area Upstream Life Expectancy **** Flow Check Dams*** 2 ha 0.15 m/s 0.5 % N.A. N.A. 45 days Straw Bale Flow Check Dams Fiber Roll Flow Check Dams Sand Bag Flow Check Dams Rock Flow Check Dams* Ponding Water to Control Sediment Light-Duty Sediment Barriers *** Light-Duty Straw Bale Barriers Light-Duty Silt Fence Barriers Light-Duty Fibre Roll Barriers Heavy-Duty Sediment Barriers *** Heavy-Duty Silt Fence Barriers Heavy-Duty Wire-Backed Silt Fence Barriers 2 ha 0.3 m/s 0.5 % N.A. N.A. 45 days 2 ha 0.15 m/s 0.5 % N.A. N.A. 6 months 2 ha 1 m/s 0.5 % N.A. N.A. 6 months 4 ha 2 m/s 0.5 % N.A. N.A. 6 months N.A m/s N.A. 3:1 30 m/1000m 2 45 days N.A. 0.3 m/s N.A. 3:1 30 m/1000m 2 45 days N.A m/s N.A. 3:1 30 m/1000m 2 6 months N.A. Roll size dependent N.A. 3:1 30 m/1000m 2 45 days N.A m/s N.A. 2:1 30 m/1000m 2 45 days N.A m/s N.A. 2:1 30 m/1000m 2 6 months N.A m/s N.A. 2:1 30 m/1000m years Berm Barriers N.A. 1 m/s N.A. 2:1 30 m/1000m 2 6 months Sand Bag Barriers N.A. 1 m/s N.A. 2:1 30 m/1000m 2 6 months Fibre Roll Grade Breaks N.A. 1 m/s N.A. Up to 1:1 30 m/1000m 2 6 months Sediment Traps 2 ha 1.5 m/s N.A. N.A. N.A. 6 months Sediment Traps for Dewatering Filter Bags Pump size dependent N.A. N.A. N.A. N.A. 6 months ** Pump and sediment particle size dependent N.A. N.A. N.A. N.A. Variable per manufacturer s direction January 2016 Page 9 of 10 B805

10 Temporary Control Measure Catchment Area Isolating Sensitive Areas and Work Areas Flow Velocity Turbidity Curtains N.A. 0.3 m/s Coffer Dams Light-Duty Sediment Barriers *** Heavy-Duty Sediment Barriers *** Channel Slope Barrier Length/Unit Area Upstream all in-water body controls require site specific engineering design all in-water body controls require site specific engineering design Life Expectancy **** 2 ha 0.15 m/s N.A. 3:1 30 m/1000m 2 45 days 2 ha m/s N.A. 2:1 30 m/1000m 2 45 days Slope Drains 2 ha N.A. N.A. 1.5:1 N.A. 6 months Diversion Ditches 2 ha N.A. 6 months * Rock Flow Check Dams intended for placement in situations which exceed the limits outlined in this table require site specific engineering design. ** Life Expectancy of Sediment Traps for Dewatering is dependent on the type of sediment barrier used in its construction. *** Minimum design criteria have been used for the general category control measures. If this limit is to be exceeded, the designer must specify a specific measure. **** Life Expectancy assumes that regular maintenance is being undertaken. January 2016 Page 10 of 10 B805

Temporary Erosion Control

Construction operations And methods **Temporary Erosion Control** The test will more than likely just have a basic word problem dealing with Erosion control, if it has anything on the test. So just review,