Tips with Creation of your Erosion and Sediment Control Plan

Transcription

1 Tips with Creation of your Erosion and Sediment Control Plan By Chris Droste, CESCO Senior Erosion Control Specialist Westmoreland Conservation District

2 Forming Your Narrative Use the DEP checklist. Page in DEP E&S manual Page details everything you need to provide in the plans.

3 Tips when forming a Narrative We suggest presenting all calculations for controls such as traps, basins, channels, in standard format from the DEP manual If using your own spreadsheets, present ALL of the data required from the DEP worksheets.

4 Drawing Details Stage the E&S control design: - Clearing and grubbing and topsoil removal - Phase 1- controls for bulk grading - Phase 2- Controls for building pads, homes, roadways.

5 General sequence of Controls Establish limits of clearing Install rock construction entrance first Clear landing area for equipment Clear area for installation of Silt fence Clear areas only for installation of sediment traps, basins, Diversion and collector channels if called out in plan. Construct Diversion channels Construct basins, traps Then, Construct collector channels to the basins and traps Begin stripping of topsoil and grading activities

6 General Tips and suggestions for control installation and sequence Keep collection channels from interfering with the work area. Channels should be positioned below fills or bulk grading areas Avoid traps and basins that cannot be installed until the fills are to grade. Access roads are best controlled with compost socks or sock traps.

7 Plan Example: design channels and traps to catch the most runoff

8 Surveying issues Flying a site without verifying the site conditions can lead to problems with your plan. Surveying is important You may miss important features such as: Ravines Steep slopes Drainage paths Wetland areas

9 Site survey problems with E&S control installations Problems with trap and channel installation can happen Entering Channel is the same elevation as trap bottom

10 Access to the site

11 Site Access

12 How do you control the runoff from entrance roads?

13 Initial Site access E&S control design When you have steep entrance cuts, how do you control the runoff during excavation? Use a small sediment trap to the side of the entrance. Use cutoff channels, or water bars or broad based dips to take water to traps. Wash racks may be required for HQ/EV watersheds

14 Runoff control at site entrances Trap installed at entrance to site

15 Direct access road water to compost filter traps

16 Controlling narrow and long access roads Plans show a compost Filter sock trap at the entrance with water bars To direct runoff from the road into the trap.

17 Sediment Barriers

18 . Calibri All Sediment barriers must be installed on existing level grade

19 Silt fence

20 Detail. Calibri Standard (18 ) Silt Fence Fabric width shall be 30 minimum. Stakes shall be 2 X 2 hardwood or equivalent steel (U or T) stakes.

21 Compost socks. Calibri

22 . Calibri Compost socks avoid: Using 8 diameter socks anywhere other than for small (<1/4 acre) house lots

23 Sediment traps:

24 Tips with design of traps Fine clay soils require larger sized traps. Ex. (5 acre traps would require 115 x230 surface area.) If you cant fit this size trap, then: Fore bays can be used Turbidity curtains can be used Flocculants can be used

25 Please utilize the charts for calculations for trap design!

26 What to do when Riser holes are blocked with debris Riser holes are blocked with straw And debris Solution is to install a rock filter of 2B stone around the base to drain The lower holes

27 Standard Detail # 7-11 The plan details can include this detail of the riser to prevent clogging

28 Sock traps

29 Compost sock trap

30 Design is critical with sock traps To function properly Socks not high enough Socks are stacked high enough

31 Where is a good location to outlet the trap or basin? Defined waterway channel (best) Municipal storm sewer Roadside swales Level spreader Well Vegetated areas, embankment traps.

32 Structural Level spreaders can work well provided you Have a good vegetated field, and an easement!

33 The use of T-box outlets are an excellent way to discharge below the basin into a dry ravine

34 Selecting locations to discharge Know what you are discharging your water into! Look for collapsed or blocked Culverts Look for proper sizing of culverts Example: discharge pipe= 36 Culvert pipe= 18

35 Selecting locations to discharge Look at the downstream impacts to: - Driveway culverts Roadside swales Spring seeps

36 Problem: Partially collapsed Culvert CMP metal pipe has the bottom rotted out and could collapse * this should be replaced prior to basin construction

37 Know what your discharging to is very important!

38 Roadside swale discharge Analyze swale so not to create a hazardous situation!

39 Leaving room for your basin, trap, and channels.

40 Leaving room for basins, Traps, and Channels Think of the design of appropriate erosion controls first! Access is necessary for equipment to maintain controls. Long linear traps and basins may fit the site better.

41 Problems: Not leaving room for proper controls The site is not controlled properly Sediment pollution is more of a risk Resident impacts Traffic safety impacts

42 Leave room for basins and traps A trap was installed here but barely fits Access is hard for equipment To maintain channels and trap

43 Take into account when designing the sock traps, you need Access for machines to clean them out!

44 Sediment Basin design tips

45 Details. Calibri Utilize the standard design details in your plans and narratives!

46 Permanent storm water trash rack for Type M inlet box risers Raised open frame design Allows more flow Prevents backing up water over principal spillway

47 Stone berms around riser help filter fine clays for better performance

48 . Calibri

49 Sediment Fore-bays Can help reduce requirement of flow length to Width ratios of 2:1.

50 Baffles Help keep sediment to one side of basin or trap for easy cleanout. Orient baffles to contain sediment at incoming channels

51 Multiple baffles are sometimes required to achieve proper flow length

52 Using Jersey Barriers as baffles Contractor can clean out basin easily

53 Outfall barrels

54 Outlet Barrel Installation Detail

55 Barrel and anti-seep collar installation * HP (grey) polypropylene pipe is used in this example

56 Long discharge outfalls may need Drop manholes to reduce energy

57 Designing collection swales and berms

58 Collection channels

59 Tips on designing Collection Channels and Linings: Collection channels to traps and basins - Trapezoidal channels are more stable - Utilize linings that have woven coconut blends, curled wood types, plastic mesh. - Provide the manufacture in the design details. - Rip rap channels cannot be cleaned out

60 Temporary collection channel Avoid bed-slopes less than 1% Avoid Rock check dams in channels to slow water down Avoid sharp bends Road crossing pipes need adequately sized to channel dimension.

61 Emergency spillways should not be next to a collection channel Adjust the locations not to interfere with function of each

62 Top of slope berms, benches and slope pipes Control water during and after fill placement Berms must at least be 2 wide and a minimum of 1 high to prevent water from spilling over the slope. Use Slope pipes to control ponding water behind the berm. Pipes should discharge to traps, channels or benches.

63 Top of slope berms

64 Top of Slope berm detail with incremental fill layers

65 Benches: Width should be minimum 6 Depth at inside minimum 1 Maintain the dimension at all times of fill levels.

66 Benches On large fill sites, leaning fill back as layers progress can Help with water control and prevent slope washout and failure

67 Top of slope benches Top is benched back 2-3% to inside to control water

68 Slope pipes

69 Slope pipes need sized for drainage areas Undersized pipes result in overtopping washing beside pipe and Causing severe slope erosion

70 - Compost traps control the fill as its brought in - Top of slope berms and pipes control bench water at final grade

71 Using Benches in fill slopes with slope pipes Install slope pipe here from slope berm Bench channel controls Runoff from upper fill

72 Road grading and controlling runoff Roads can contribute to runoff problems

73 Water bar use on during road grading operations Not recommended for active roadways

74 How do you control water on roads that are not paved yet?

75 Berms are used behind inlets on roadways to capture runoff Compacted earth berm 2-3 feet high and 3 foot Wide. Inlets drain to a sediment basin to treat runoff

76 Stabilization: Selecting seed mixtures for your site

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80 Specify incremental Seeding in plans On long, steep cut slopes, seeding/ blanketing should occur in 15 increments

81 Slope stabilization methods Slope blankets should be selected as to allow grass to grow through media easily. (Straw with Net) blankets work well to allow grass to grow. Bonded Fiber Matrix or spray on Blankets work well.

82 The End Questions? Contact info: