INSPECTION & MAINTENANCE OF BMPs: PROGRAM COMPONENTS & ASSET MANAGEMENT

Transcription

1 INSPECTION & MAINTENANCE OF BMPs: PROGRAM COMPONENTS & ASSET MANAGEMENT APWA ANNUAL CONFERENCE Fernando Pasquel Noelle Slater May 2016

2 Learning objectives Recognize the benefits of a well-structured stormwater inspection and maintenance program Describe elements of a maintenance program and evaluate how design considerations can impact maintenance needs. Demonstrate how EPA/WERF s 10-step AM process can be used as a framework to develop and implement a stormwater asset management program. 2

3 Outline Stormwater Best Management Practices (BMPs) Types of BMPs and how they work An asset management approach to maintenance Inspection and Maintenance of BMPs Why do BMPs need to be maintained Elements of a maintenance program Routine and non-routine maintenance needs May 19,

4 Types of stormwater BMPs Stormwater Asset Category Basins Swales and Strips Filters Example Types of Assets Dry basins Cisterns and rain barrels Wetlands Swales Level spreaders Surface and subsurface sand filters Landscaped / vegetated roofs Manufactured filters (boxes) Wet basins Vaults and swirl concentrators Forebays Vegetated strips Bioretention Drain inlet inserts Subsurface gravel wetlands Infiltrators Gross Pollutant Traps and Mechanical Operations Infiltration basins Dry wells Screens Baskets Hoods Infiltration trenches and vaults Permeable pavement Nets Racks Adapted from Design of Urban Stormwater Controls (WEF Press, McGraw Hill, 2012) 4

5 How BMPs work: factors in BMP design Volume (runoff inflow and outflow) Velocity Resuspension (consideration of by-pass flows) Pollutant concentration Dissolved or suspended pollutants 5

6 How BMPs work: use different pollutant removal mechanisms Storage Settling Filtering Biological and chemical processes Evapotranspiration Soil infiltration 6

7 BMP design and maintenance criteria need to be improved Routine maintenance is not being performed BMPs are failing Performance feedback is needed to address design and maintenance needs 7

8 Implement Asset Management 8

9 Asset Management definition adapted from USEPA Asset Management is a body of management practices that Is applied to the entire portfolio of infrastructure assets at all levels of the organization Seeks to minimize total costs of acquiring, operating, maintaining, and renewing assets Works within an environment of limited resources Delivers service levels customers desire and regulators require Targets acceptable level of risk to the organization 9

10 There is more to Asset Management than Data Collection 10

11 EPA/WERF s 10-step process provides a framework for asset management 11

12 A well-defined AM structure is critical ASSET GROUP Outfalls/ Pipes Junctions/ Chambers Pumps ASSET TYPE Pipe Pipe Inlet Pipe Outlet Manhole Catch basin Junction box Drop inlet Pump Gate Valve ASSET COMPONENT Manhole Catch basin Headwall Flume Walls Chimney Lid Motor (if <100 HP pump) Familiar Assets 12

13 A well-defined AM structure is critical ASSET GROUP Open Linear Systems BMPs/GI ASSET TYPE Ditch Channel Swale Rain gardens Bioswales Wet ponds Dry ponds Constructed wetlands Manufactured devices ASSET COMPONENT Check dams Vegetation Forebay Overflow / riser Channel Vegetation Structure protection Non-Traditional Assets 13

14 A key focus of the Asset Management process is Risk-Based Evaluations Risk Is a Simple Equation: Probability * Consequence 14

15 Condition assessment helps determine probability of failure Condition Type Failure Mode Description Assessment Method Capacity Does not meet demand (flow, loading, storage volume, etc.) Test or Desktop Performance Level of Service Does not meet functional needs (regulatory permits, customer commitments) Desktop Physical Efficiency Mortality Not lowest cost alternative (labor, maintenance, obsolescence) Current state of repair and operation as influenced by age, historical maintenance and operating environment Desktop Test, Visual, Desktop, Modeling 15

16 Probability of Failure is Higher Value of Physical and Performance Score Condition Scoring Criteria for Physical and Performance Pipes/Culverts/ Outfalls Structural (PACP) None (no/minor defects, failure is unlikely) Erosion None (No erosion near barrel observed) Trash None (No trash or debris present) Sedimentation Odor None (No sedimentation present) None (No odor present) Slight (minor defects, pipe is unlikely to fail for 20+ years) Slight (Slight erosion near barrel, no imminent concern on condition of barrel) Slight (Limited trash and/or debris present) Slight (Limited sedimentation) Slight (Limited odor detected, may be sign of illicit discharge) Moderate (has moderate defects and will likely fail in the next years) Moderate (noticeable erosion near barrel that could lead to future collapse or pipe failure) Moderate ( Trash and/or debris present, but will not cause flooding or inhibit O&M or emergency operations) Moderate (Sedimentation present, but will not cause flooding or inhibit O&M or emergency operations) Moderate (Detectable odor present, likely sign of illicit discharge) Severe (has severe defects and will likely fail in the next 5-10 years ) Severe (severe erosion/undercutting around barrel, collapse or failure could oocur) Severe (Trash and/or debris present that will likely cause flooding or inhibit O&M or emergency operations) Severe (Sedimentatoin present that will likely cause flooding or inhibit O&M or emergency operations) Severe (Severe odor present, definite sign of illicit discharge) Failure (has failed or will likely fail in the next few years) 16 Failure Failure Failure Failure

17 Physical condition examples Condition Score 1 Condition Score 5 17

18 Multiple stormwater assets example Stormwater Assets: Detention basins 6 Retention basins 4 Storm filters 3 Underground pipe 1 Filterra 23 Streams/Channels 2 18

19 Condition ratings for all stormwater asset types Condition Assessment Rating Object ID Location ID Asset ID Technology/ Type Structure Number Structural Problem Erosion/ Sedimentation Vegetation Clogging Trash Pretreatment Device Inspection Comments Detention Fenced but unlocked, 3' to top of trash rack, odorous Detention WCVE concrete outlet structures with slot drains at grade. No inlet into pond, berm around perimeter Retention Home Depot Fenced but unlocked, section of fence missing. Heavily silted, oil sheen on water Detention Locked behind 6' fence. Property management said Chesterfield County has the key. Pond is overgrown and doesn't appear to have any inlet or outlet structures Extended Detention # Sedimentation issue: 1 inlet causing scour, 2 others are silted in Extended Detention # Concrete inlet pointed directly at outlet, PVC inlet silted Filterra F Curb inlet coming in Storm Filter Sedimentation issue Detention Completely overgrown and silted in Retention # Fenced in, could not gain access. Four roof drains appear to drain in to pond as well as whatever over land surface flow enters Retention # Fenced in, could not gain access 19

20 Which assets to repair/retrofit? Total Score No. of Assets Percent Repair Priority % None % Low % Medium High Total % 20

21 Benefits of Asset Management Informed asset investment decisions Managed risk Demonstrated compliance Improved organizational sustainability Improved efficiency and effectiveness Improved services and outputs Demonstrated social responsibility = Real organizational savings (reduced borrowing costs, right-timed asset replacement, reduced asset failures) 21

22 Why BMPs Need Maintenance 22

23 Maintenance of BMPs? No BMP is maintenance free A properly cared for stormwater management facility can work effectively for years without major maintenance costs Neglected, a stormwater BMP can potentially be a continual financial drain May 19,

24 Maintenance requirements will change as BMPs age

25 Maintenance requirements will change as BMPs age 25

26 Maintenance requirements will change as BMPs age 26

27 Outflow impacts on maintenance requirements 27

28 Downstream impacts on maintenance requirements 28

29 Dry Ponds specs and debris management 29

30 Retrofitted pond 30

31 Inspections 31

32 Inspections? 32

33 Spillway maintenance 33

34 34

35 Establish a Maintenance Program 35

36 Identify BMP characteristics Dry Pond Wet Pond Infiltration Trench Bioretention Facility Vegetated Swale Permeable Paving Vegetated Rooftop Underground Detention Manufactured Device 36

37 Define maintenance tasks Regular Inspections Vegetation Management Embankment and Outlet Stabilization Debris and Litter Control Mechanical Components Maintenance Insect Control Access Maintenance Overall Pond Maintenance Sediment/Pollutant Removal Components Replacement Source: City of Portland, OR 37

38 Identify costs and allocate resources Type of BMP Annual Maintenance Cost* Wet Pond $1,000 to $100,000 Dry Pond $1,000 to $100,000 Infiltration Trench $1,500 to $2,000 Bioretention System $1,500 to $2,000 Vegetated Swale $500 to $1,000 Permeable Paving $500 to $1,000 Vegetated Rooftop $500 to $7,000 Underground Detention $1,000 to $1,500 Manufactured BMP $500+ *- based on costs from WERF and Northern Virginia Regional Commission publications 38

39 Identify costs and allocate resources Annual Maintenance Cost GI Type Unit Low Avg High Bioswale sf $0.06 $0.15 $0.22 Bioretention Basin/Rain Garden sf $0.06 $0.15 $0.22 Rain Barrels / Cisterns gal $0 $0 $0.05 Porous/Permeable Pavement sf $.09 $0.16 $0.23 Green Roofs sf $0.02 $0.25 $0.40 *- based on costs from WERF and Northern Virginia Regional Commission 39

40 Perform routine inspections Detect issues early First line of defense to ensure optimal operation Helps avoid long term problems Source: Northern Virginia Regional Commission 40

41 Regular inspections reduce maintenance costs Inspection Checklist Remove obstructions of the inlet or outlet devices by trash and debris Look for excessive erosion, scouring, or sedimentation in the pond perimeter, inlets, outlets, and energy dissipaters Look for cracking or settling in the embankment, dam, inlet and outlet structures Look for animal burrows, nests, or lodges Look for permanently ponded areas in the bottom of an extended-detention dry pond or bioretention facility Look for sluggishly draining infiltration devices Look for algae growth, stagnant pools, or noxious odors Look for poor or distressed stands of grass 41

42 Regular inspections reduce maintenance costs Inspection Checklist (continued) Look for distressed aquatic vegetation Look for deterioration of pipes and conduits Look for piping along the outlet barrel Look for deterioration in the emergency spillway (grass should not be cut to less than 8 inches in height) Look for washouts, bulges or slumps, and woody growth in the embankment Identify seepage at the toe of wet ponds or constructed treatment wetlands Identify unstable side slopes and embankments Document deterioration of downstream channels Document signs of vandalism 42

43 Provide proper/consistent training Provide guidance on proper maintenance techniques for different BMPs Keep staff up-to-date on changes in BMP technology Provide instruction on use of maintenance equipment Source: King County, WA Source: NYCDEP 43

44 Keep records of maintenance Identifying persistent problems by asset type Identify chronic maintenance problems by location Aid in future budget preparation Source: Clemson University 44

45 Don t forget to involve the public! Educating and involving the community is a cost-effective way to prolong the life of the stormwater BMPs Activities can range from organized clean-up days to a community-wide education program Supplies, resources, and technical support should be provided to businesses and communities Source: Alliance for the Bay 45

46 Provide routine maintenance Costs are relatively consistent and can usually be predicted for an annual budget Typical range is 1 to 10% of original capital construction costs per year depending on BMP type and size Source: City of Wilmington, NC 46

47 Considerations for frequency of maintenance Visibility of the Facility/ Aesthetics Landscaping Upstream Conditions Source: NDRC Safety Need for Professional Judgement Financing Source: City of Berkeley, CA 47

48 Wet/dry pond maintenance Cleaning and removal of debris Harvesting vegetation Repairing embankment and side slopes Repairing control structure 48

49 Bioretention facility maintenance Remove invasive plants Remove sediment and replace soil periodically Replace mulch annually or as needed Source: University of Maryland 49

50 Plan for non-routine maintenance Non-routine maintenance is highly specific and varies depending on different factors Costs can be substantial over the long run, especially when considering the possibility of eventual BMP replacement Source: Lakeside Marine Construction Having a dedicated BMP maintenance fund account to cover these costs is highly recommended 50

51 Non-routine maintenance items Major sediment removal Inflow and outflow pipes Trash racks and anti-vortex devices Valves, orifices, and aerators Concrete structures (riser structures in ponds, etc.) Pumps and switches Manhole covers and access hatches Earthworks such as embankments and side slopes Mulch and vegetation 51

52 Summary Old Problems Reactive response to BMP maintenance Limited funding New Solutions Proactive response to BMP maintenance Establish a maintenance program Implement an asset management approach to maintenance Provide routine and non-routine maintenance 52

53 Contacts Fernando Pasquel, CPM Senior Vice President, Arcadis National Director, Stormwater & Watershed Management Contact: , Noelle Slater Senior Environmental Engineer, Arcadis Expert in MS4 compliance and BMP design Contact: ,

54 Thank You! 54

55 Infiltration trench maintenance Cleaning and removing debris and sediment Mowing upland vegetation Repairing/replaci ng aggregate Maintaining inlets/outlets Source: Montgomery County, MD May 19,

56 Vegetated swale maintenance Remove sediment, replace check dams (usually made of earth, riprap, or wood) Reseed or sod (if grassed) or replace dead plants, every two years May 19,

57 Permeable Pavement Maintenance Vacuum sediments from surface, twice a year Remove garbage and debris May 19,

58 Vegetated roof maintenance Repair leaks, as necessary Replenish soil and plants, annually Install an irrigation system or provide supplemental watering if drought is a concern Source: NYCDEP May 19,

59 Underground detention maintenance Vacuum accumulated sediment and debris, twice a year May 19,

60 Manufactured device maintenance Vacuum accumulated sediment, oil, and debris, every six months, or as required Source: Contech May 19,

61 When is sediment removal needed? Sediment depth is damaging or killing vegetation, sediment is preventing the facility from draining in the time designed (usually hours) or 50% of the volume has been lost Source: City of Charlotte/Mecklenburg County, NC For underground storage, at least annually or when the basin is half-full Source: City of Amherst, NY 61

62 Sediment removal Type of BMP Sediment Removal Frequency Facility Life Span* Wet Pond 5 to 15 years 20 to 50 years Dry Pond 2 to 10 years 20 to 50 years Infiltration Trench Monthly or as needed 10 years Bioretention System 5 to 10 years 10 to 25 years Vegetated Swale As needed 10 to 25 years Permeable Paving 3 to 4 times per year 25 years Vegetated Rooftop Every 5 years 25 years Underground Detention Annually or as needed 10 to 30 years Manufactured BMP Annually or as required 20 to 100 years *- Assumes the facility is maintained on a regular basis 62

63 Performance examples Capacity Regulatory O&M / Availability Obsolescence 63

64 Risk Assessment provides apples-toapples comparison across all assets District Location R-O-W Group Type Physical Score Performance Score Condition Score COF Score Risk Score City name City name City name DOT Pipe Pipe DOT Pipe Outfall City BMP Pond City name DOT Open Linear Ditch City name DOT BMP Bioswale

65 Things happen! 65

66 Be creative! 66

67 Dry Pond? Spillway Location Slope Maintenance 67

68 Spillway maintenance 68

69 Spillway maintenance 69