Sediment Control and Pollution Prevention Presentation 3 of 3

Transcription

1 Sediment Control and Pollution Prevention Presentation 3 of 3 This presentation was produced by the JOHNSON COUNTY STORMWATER MANAGEMENT PROGRAM 1800 W. 56 Highway Olathe, KS 66061

2 Sediment Controls Device or product which will slow the overland flow of storm water and allow the energy to dissipate so soil particles fall out prior to the storm water leaving the construction site. If there is not enough energy in the storm water flow to keep the soil particles suspended then they will settle out.

3 Sediment Controls Silt (Sediment) Fence Wattles Ditch Checks/Check Dams Level Spreader Slope drains Inlet Protection Outlet Protection Detention/Retention Basins This training program does not cover straw/hay bales as many states and municipalities do not allow them to be used.

4 Silt fence as terraces Throughout this presentation we will refer to sediment barriers as silt fence since that is the common name in the industry; although, it should be referred to as sediment fence. Silt fence is the most over-used and misused product in our industry. Hopefully this course will introduce you to other products or devices that work as well or better than silt fence.

5 Silt Fence (sediment control fence) Woven, non-woven, or monofilament geotextile Woven Non-woven Mono-filament

6 Silt fence must be installed on the contour

7 Where are the stakes? When using silt fence to collect stormwater at a concentrated area, it is very important to reinforce the fence with extra stakes or wire backing.

8 Methods for Burying Trencher Slicing

9 Proper installation will hold water

10 There is a front and back to silt fence! The posts and wire-backing should be installed on the backside or down-gradient side of the fence.

11 Trenching

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13 Slicing The other way to install silt fence is to slice it in place with a machine specialized in silt fence installation.

14 Slicing Installation Embedded tightly to reduce the risk of blow out underneath the fence No open trench Fast

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16 Flexible Self Supporting Silt Fence

17 Proper Silt Fence Installation Placed along the contour with a slight turn up gradient at the ends. Only placed in those areas where stormwater leaves the site via overland flow. Never placed in concentrated flow areas It should be relocated as necessary when soil movement and land grading changes the overland flow patterns.

18 J-Hooking Designs called J-hooks insure water & sediment pond behind each silt fence like small sediment traps.

19 The picture on the right is of J-hooks which will gather smaller amounts of water flowing down gradient and treat the storm water multiple times before it exits the construction site. Silt Fence J-Hook J The installation on the left will concentrate the entire flow along the fence and could create erosion of the soil in the trench and a blow out under the fence.

20 Leave room for sediment storage at the toe of a slope. Erosion control is need until vegetation is established.

21 Other Perimeter Control Methods Triangular Foam Dike Sand or gravel bags

22 Ditch Checks / Check Dams Rock Ditch Checks As shown in the detail for a rock check dam there is a proper spacing to check dams. Alternative Products: Fiber Tubes Foam Dike Ridge Ditch check Wattles Degradable Non-degradable NOTE: KEY STONE INTO CHANNEL BANKS AND EXTEND IT BEYOND THE ABUTMENTS A MINIMUM OF 18" (0.5m) TO PREVENT FLOW AROUND DAM. FLOW FILE: RCKCHKDM 24" (0.6m) VIEW LOOKING UPSTREAM SECTION A - A `L' = THE DISTANCE SUCH THAT POINTS `A' AND `B' ARE OF EQUAL ELEVATION. POINT `A' 18" (0.5m) A 6" (150mm) SPACING BETWEEN CHECK DAMS A 8' (2.4m) NOT TO SCALE `L' 24" (0.6m) POINT `B' ROCK CHECK DAM

23 Incorrect Silt Fence Placement

24 Silt fence does not work in concentrated flows

25 Bio-Degradable Wattles/Logs Straw Excelsior/Wood Coconut/Coir Mulch Compost Not used for chemical containment.

26 Fiber Filtration Tubes Composite of wood fibers and man-made made fibers Polymers encased in knitted cylindrical tubes Designed for flow, filtration and flocculation

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28 Piedmont Red Clay Soil

29 This product will need to be replaced after it has filled with sediment but this is a good soil amendment so you can incorporate the logs into your topsoil mix.

30 Erosion Tubes This is a new wattle product that can be reused and moved from site to site. The tube is filled with wood and recycled tire product.

31 Triangular Foam Dike Fast & Easy Installation Effective Sediment Control Conforms to Rough Terrain Lightweight & Durable

32 Used in roadside ditches

33 In front of an inlet

34 Ridge Check Installation Channels Ditches High flow or concentrated flow areas Must be used in conjunction with a TRM Maintenance is somewhat difficult

35 Installation

36 In this picture we see the Geo Ridge is replacing straw bales across the channel. During the installation it began to rain.

37 The rolled erosion control products were not all installed yet at the time of the rain event and a large volume of water was moving down the swale.

38 Backside Front side

39 As the rain let up, this is the resulting sediment capture behind the dam just from slowing the flow of the stormwater.

40 Level Spreaders Used to diffuse concentrated flows to reduce the energy in the flowing water and the potential for erosion. They can be designed ed in many ways: Swale with a level wall so the water flows over evenly and spreads out over established vegetation Long T-pipe T at outflow with perforations to allow small amounts of water to discharge over a long section of pipe to dissipate the t overall point source discharge.

41 Swale Level Spreader - reducing scour and increasing infiltration.

42 T-Pipe Spreader

43 Slope Drains Used to reduce the amount of surface flow down a slope via terraces Collects small amounts of surface flow and directs the flow to the bottom of the slope via a pipe. Needs energy dissipation at the discharge point of the pipe at the bottom of the slope.

44 Stormwater flow is collected along a terrace and directed to a pipe then discharged at the bottom of the slope. There should be an energy dissipation device at the end of the pipe and no silt fence at the discharge point.

45 Inlet Protection There are a number of inlet protection devices that can be built around an inlet. These include: Block and gravel Silt fence drop inlet Gravel and wire mesh drop inlet Wooden weir curb inlet Excavated drop inlet sediment trap You need to check the design standards for your area to determine which of these are allowed to be used on your construction site.

46 No matter which device you use you must have a detail for that device and build it per the detail.

47 Other Inlet Products

48 Underground Device

49 Grate Cover This product fits around the grate and provides an overflow. This will reduce the depth of ponded stormwater in the area.

50 Carpet Roll This product is made from recycled carpet fibers and has holes to allow the ponded water to drain.

51 Compost sock With the use of compost socks, the compost can be added to the soil after use in a sock and is an excellent soil amendment.

52 Dewatering A compost or mulch filled socks can also be used for dewatering when placed in an area that is vegetated and will not erode.

53 Domed Device

54 Here a silt fence inlet protection device is used along an interstate drain.

55 It is removed and a silt saver is installed in it s place.

56 Pond Skimmers For dewatering sediment basins and wet ponds. A device like this one will float on the surface and remove the cleaner top water.

57 Monitor the device. Dewatering is discontinued when it gets down to the more turbid waters near the pond bottom.

58 Ponds Sediment Trap Small Temporary Detention Pond Outlet at the bottom Grass lined Retention Pond Outlet at the top Holds water

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60 Detention ponds and infiltration basins will work much more efficiently with a full, dense stand of vegetation.

61 Retention (Wet) Pond

62 Energy Dissipation at the end of a pipe Need to reduce velocity by: Slowing the flow Spreading the flow out This will reduce the potential for scour and erosion of the area around and down hill of the discharge. There should always be surface protection downstream of a point source discharge to protect the soil and vegetation from a high velocity discharge.

63 Short Circuit Design Inflow Outflow Construction of a baffle or weir is need to direct the flow out into the pond. This will add distance between inflow and outflow and greatly increase the effectiveness of the pond.

64 Pollution Prevention Good Housekeeping Phasing of BMPs Sequence of construction Track out

65 Good Housekeeping Solid Waste Hazardous Waste Sanitary Waste

66 Good Housekeeping Keep site clean Designate areas for waste disposal (locate away from sensitive areas) Arrange for regular waste collection Cover and contain wastes Educate your site personnel

67 This is not a pretty site (sight)!

68 Material Delivery and Storage Designate areas for delivery and storage (locate away from sensitive areas) Cover and contain materials Inspect after rain event

69 Secondary Containment Device

70 Concrete Wash-Out Avoid paving and concrete work during rain events Designate a concrete wash-out area and inform concrete truck drivers Prevent saw cut slurry, concrete acid washes and other wastes from entering storm drains Educate your subcontractors

71 Concrete mixer over the inlet? Should be located in an upland area with perimeter controls

72 Spill Reporting and Clean-Up The construction site should have a spill center and spill kit and they should be inspected and maintained with all over site best management practices. If a spill occurs of petroleum product or hazardous material check the SWPPP for the reportable quantity

73 Accidental Spills Contractor will immediately contain the spilled material. All hazardous waste material will be cleaned up and disposed of by the Contractor in the manner specifies by local, state, and federal regulations. As soon as possible the spill (if reportable), will be reported to the appropriate local, state, and federal agencies. Contractor will prepare a written record of the spill

74 Sanitary Wastes Portable toilets are considered best management practices for sanitary waste They need to be located on the site map They need regular inspection and maintenance They should be located away from waterways and inlets Some areas require secondary containment for them.

75 Phasing BMPs BMPs should be installed prior to any earth disturbing activities in any area. As construction progresses, BMPs should be modified, moved, and otherwise adjusted as necessary.

76 Sequence of construction Disturb as little of the existing vegetation as you can throughout construction. Re-establish establish temporary or permanent vegetation on any and all areas as soon as possible (especially outlots, later phases and perimeters). All ponds, basins and traps shall be vegetated immediately after installed.

77 Track Out Maintain construction exit to reduce track-out Sweep public street at the end of each day if sediment is on it Do NOT wash sediment from street into storm drain. This is the one BMP that all passer-bys notice!

78 Is this Construction Exit working? The exit should be rough with a stone size of 2-3 inches. The rock is suppose to make the truck bounce to drop the mud and dirt off the tires. When the rock voids fill up with sediments and makes the exit smooth, it no longer is a functioning practice.

79 Industrial Wheel Wash Systems Commonly used in the mining and landfill industry.

80 Rumble Plates There are also rumble plate type devices that cause the trucks to vibrate as they go over and the vibration will make dirt and mud dislodge from the trucks.

81 Mud Mats Mud mats, these devices spread the weight of the tires so they do not leave wheel ruts. It can also be used as a mat on small house lots or where vehicles bring in supplies.

82 The End. This was the third and final Erosion and Sediment Control presentation. If you have reviewed the other two presentations proceed to the Quiz Good Luck!