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Overview of Construction BMPs

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Presentation on theme: "Overview of Construction BMPs"— Presentation transcript:

1 Overview of Construction BMPs
Scott Taylor, P.E., CISEC

2 Construction BMP Review
Erosion controls Sediment controls Tracking controls Material and waste storage 2

3 When Should BMPs be Implemented?
Perimeter controls should be installed before breaking ground In preparation for a rain event In all areas that have been inactive for >14 days At all times – ‘appropriate’. This means if there is a discharge, there is no excuse Permit does not have a ‘rainy season’ 3

4 Erosion Controls Erosion controls provide 80% of sediment management
Sediment controls provide 20% of sediment management Protect surface from rain drop impact Help retain moisture in the soil Minimize the down-slope transport of soil particles They will degrade over time 4

5 Erosion Controls: Soil Binder
Generally temporary and may require reapplication Soil type dictates kind of soil binder to use Must be environmentally benign Typically last months Polyacrylamide (PAM) is an effective, low cost option 5

6 Erosion Controls: Mulches Hydraulic Mulch/Bonded Fiber Matrix
Most types need 24 hours to dry before rainfall occurs Hydraulic mulch generally good for 3 – 6 months Bonded Fiber Matrix may last several wet seasons Mixture of mulch and binder Maximum slope about 4:1 Place over previously seeded area, or add seeds to the mixture 6 V

7 Erosion Controls: Rolled Erosion Control Products
Used when disturbed soil may be difficult to stabilize or drying time an issue Blankets and mats may need to be removed and disposed of prior to application of permanent soil stabilization Install perpendicular to contours 7

8 8 V

9 Erosion Control Cost/Performance
Category Material Cost/acre Sediment Reduction (%) Longevity Binders Guar $410 80 Short Starch 60 Acrylic polymers $1,232 40 Polyacrylamide 55 Mulches Straw $2,100 90 Medium Cellulose Fiber $900 Recycled Paper 50 Bonded Fiber Matrix $5,400 Rolled Erosion Control Products Woven Jute Mesh $6,500 70 Excelsior $10,600 85 Long Straw Blanket $9,000 87 Coir (coconut shells) $13,000 Plastic Mesh Woven $2,000 9

10 Erosion control = turbidity control
Spray-on Erosion Control Video

11 Installation is critical for RECPs!
RECP Video

12 Sediment Controls: Fiber Rolls
Locate on level contours Use at top and on face of slopes Good for perimeter control Use recommended spacing in 2009 CGP Must be installed correctly: trenched and staked 12




16 Sediment Controls: Silt Fence
Located level on contours, not perpendicular Not for concentrated flow areas Must be keyed in (bottom six inches must be buried) 16

17 Sediment Control: Inlet Protection
Protect active inlets year-round Use where ponding won’t encroach into traffic Maintain/clean out after every storm 17

18 Sediment Control: Sediment Ponds
Capture and de-silt sediment laden runoff Use for large drainages and steep slopes where erosion control is not feasible Maintain/clean out on an as needed basis Video 18

19 Tracking Controls A VERY visible indicator of compliance effort (or lack of) Minimize number of access points Use coarse aggregate over filter fabric Year-round requirement In high traffic areas, street sweepers may be needed 19

20 Sediment Control Summary
BMP Application Flow Type Cost Longevity Silt Fence Perimeter Protection Sheet flow $ $9/foot 12-36 mo Reinforced S.F. Sediment Trap Shallow conc. high end of SF Fiber Roll Perimeter, inlet $1/foot (plus installation) Sed. Basin Online/offline Concentrated $2000/drainage acre Indefinite Inlet Filter Inlet Protection $200/inlet 12-24 mo Rock Entrance Tracking Controls N/a $1200-$4800 1-2 rain events Rumble Plate 20

21 Material Storage Cover and contain
Keeps site clean / good housekeeping Avoids potential sampling for non-visible pollutants 21

22 Waste Management Debris discharge from site is a permit violation!
Cover trash containers Provide water-tight concrete washouts 22

23 Example Photos

24 Inactive area with no erosion control
Soil Stabilization Potential Violation: Inactive area with no erosion control 24

25 Inactive area with erosion control BMPs
Soil Stabilization Better Practice: Inactive area with erosion control BMPs 25

26 Inactive slope with poor stabilization
Slope Stabilization Potential Violation: Inactive slope with poor stabilization 26

27 Application of soil stabilization BMPs
Slope Stabilization Better Practice Application of soil stabilization BMPs 27

28 Damaged / ineffective protection
Site Perimeter Potential Violations Damaged / ineffective protection 28

29 Proper controls & placement, well-maintained
Site Perimeter Better Practice Proper controls & placement, well-maintained 29

30 Dirt tracked onto streets,
Dirt Tracking Potential Violations Dirt tracked onto streets, lack of training 30

31 Dirt Tracking Better Practice 31 Stabilized lot & site entrances
Gravel & plates free of excessive dirt Do not avoid stabilization measures – use them! 31

32 Dust Control Potential Violations No dust control 32

33 Use water trucks for dust control
Better Practice Use water trucks for dust control 33

34 Stockpile Management Potential Violations Improper placement
No measures to prevent material discharges 34

35 Stockpile Management Better Practice Provide perimeter protection
Cover for long periods or before rain events Possibly mention that straw matting may be preferred with the new permit. Plastic degrades and falls apart in the sun. 35

36 Improper installation
Inlet Protection Potential Violations Improper installation Lack of maintenance 36

37 Inlet Protection Better Practice Use products properly
Actively maintain BMPs Prevent damage to devices Prevent pollutants from entering inlets 37

38 Poor Silt Fence Application

39 Silt Fence Potential Violations Poor installation Lack of maintenance

40 Silt Fence Better Practice Proper installation Maintained 40

41 Clean regularly – dry sweep or vacuum
Streets and Sidewalks Potential Violation Clean regularly – dry sweep or vacuum No water unless runoff directed away from drain inlets to pervious areas 41

42 Streets and Sidewalks Better Practice Well maintained 42

43 Construction Material Storage
Potential Violations No protection of soil 43

44 Construction Material Storage
Better Practice Cover, berm, and contain 44

45 Washout Pits Potential Violation Not using washout at all
Leaking / ineffective washout 45

46 Washout Pits Better Practice
Contractors must use a designated concrete washout Do not overfill Washout must be water tight 46

47 Leaking Equipment Potential Violations Leaks onto ground & no clean up
Damaged drip pans Flat oil trays Plastic does not prevent runoff 47

48 Leaking Equipment Better Practice 48

49 Good housekeeping is critical
Construction Waste Potential Violations Good housekeeping is critical 49

50 Construction Waste Better Practice
Cover trash cans/bins when storm is predicted Empty at least every week 50

51 Sawcutting Potential Violation Better Practice
Discharge to gutter/storm drain Vacuum saw cut slurry Away from concentrated flow paths 51

52 Secondary Containment
Potential Violations Storage of fuel/oils Improper storage No containment 52

53 Secondary Containment
Better Practice Do not store fuel on site Use proper secondary containment 53

54 Avoid placement in street gutter / flow areas
Portable Toilets Potential Violation Avoid placement in street gutter / flow areas 54

55 Placed out of gutters and flow paths
Portable Toilets Better Practice Placed out of gutters and flow paths 55

56 Good or Bad? 56

57 Good or Bad? 57

58 Good or Bad? 58

59 Good or Bad? Entrances/ inlet protection, fill at end of street. 59

60 Good or Bad? 60

61 Good or Bad? No controls. Will go onto street. 61

62 Good or Bad? 62

63 Good or Bad? No final stabilization. Dirt in street. 63

64 Good or Bad? 64

65 Good or Bad? 65

66 Good or Bad? 66

67 Solutions for Traditional Problem Areas
Site construction roadways, and undercut roadway sections Slopes Concentrated Drainage Areas near inlets (high energy) Final stabilization

68 Roadways Lignosulfonate
naturally occurring, glue-like polymer found in wood binds surface particles together Completely insoluble and water resistant provides dust control to PM10 standards Provides erosion control in low velocity applications

69 Roadways - Application
Scarify to the depth of cementation desired. Introduce Lignin and blade mix subgrade to optimum moisture content is reached.  The lignin is applied during the mixing process just as water would be to hydrate/condition the soil Compact with vibratory roller. Spray rolled surface once more with lignin as a topical application and let dry (24 hrs). Apply asphaltic emulsion like PASS QB (water based emulsion) so as to be dry to the touch within 24 hrs. Apply Type 2 slurry as the final layer

70 Roadways - Application

71 Slopes Slopes require good cover supplemented by a sediment control BMP A BFM or similar type of product is generally required on slopes to eliminate rilling Straw wattles are difficult to install correctly, and tend to deteriorate in less than one season – An alternative is compost socks.

72 Slope Treatments

73 Concentrated Drainage
Concentrated drainage on a construction site must be managed. Ultimate conveyances are preferred Temporary conveyances that use material for later construction stages is next best option New rules will necessitate temporary concrete ditches and rock ditches.

74 Concentrated Flow Solutions

75 Areas Near Inlets Areas at inlets are high-energy locations
Last line of defense A good practice is staged reduction in flow velocity prior to reaching the inlet pool Options: Shotcrete lining and compost socks or rock over filter fabric and gravel bags

76 Areas Near Inlets

77 Final Stabilization May require irrigation to establish vegetation
Include compost in hydroseed mix to help with water retention/germination Mulch is a good final cover for slopes Use fast-germinating seed mixes appropriate for the season (warm or cool) Blankets and BFM may be an option

78 Final Stabilization

79 Single Family Lots



82 What Would You Do Here?

83 Here?

84 Or Here?

85 Work in Creek

86 BMP in Creek

87 Sediment Basin?

88 What is Wrong? No controls. Will go onto street.

89 The Next Day

90 The Next Day

91 Stranded Water

92 Storing onsite…

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