Low Impact Development Training Module 3: Bioretention System Construction Dennis Chestnut

Sponsors 2 District Department of Transportation U.S. Department of Transportation Federal Highway Administration The Low Impact Development Center, Inc. University of the District of Columbia Funding for this project was provided through a grant from the Federal Highway Administration, U.S. Department of Transportation

Contributors 3 The Low Impact Development Center, Inc. John Shorb Landscaping, Inc. Logo Groundwork Anacostia River, D.C.

Copyright 4 Unless otherwise noted, Low Impact Development Training, funded by DDOT & DDOE, is licensed under a Creative Commons Attribution-NonCommerical- ShareAlike 3.0 Unported License. Content provided by cited entities remains the property of those entities and may not be used without their explicit permission.

Outline Doing Business in The District Preparing bids for bioretention construction Estimating construction costs Bioretention construction sequencing Common construction errors 5

Expected Outcomes Know what licenses and certifications are required to do business in The District Be able to prepare bids for construction of bioretention cells Know the proper construction sequence for bioretention cells Be able to anticipate and avoid common construction mistakes 6

Doing Business in the District 30-minute lecture to be given by a guest speaker from DCRA Licenses Certifications Training 7

Bioretention Costs and Bids Justification for costs (sources) Lump sum or line item? –Confirm certified sources (Agency schedule) –Bond costs –Means™ –Recent bids 8

Estimating Materials Costs Local sourced credits? Seasonal Availability and multiple sources Damage/breakage/theft? FOB? Labor for handling Access 9

Estimating Crew and Equipment Costs Rental/lease/own Labor certification Training time for equipment Down time Weather Scheduling Subcontracting 10

Preparing Contract Documents Terms Work times Location of contract disputes Termination Weather Unknown/Unexpected conditions Subcontracting and transferability Liability Punchlist Closeout Errors Negotiations of extras 11

Permitting Permits are needed to occupy and construct in the public ROW: –Occupancy permit Apply in TOPS (Transportation Online Permit System )‎ Issued by the DDOT Public Space Permit Office If a DDOT contractor is doing maintenance or construction in the ROW, the DDOT project manager can set up a contract record to facilitate a no-cost occupancy permit in TOPS. –Building permit Issued by DCRA Includes Soil Erosion and Sediment Control and Stormwater Management Plans, if needed 12

Working with Site Plans 13 Plans Courtesy of the Low Impact Development Center, Inc.

Interpreting a Legend 14 Plans Courtesy of the Low Impact Development Center, Inc.

Understanding Scale in Plan View 15 Plans Courtesy of the Low Impact Development Center, Inc.

Using an Engineering Scale Plans will specify the scale at which they are drawn An engineer’s scale can be used to measure distances Use the side of the scale corresponding to the specified drawing scale Markings on the scale show distances in feet Caution: make sure you are using an engineering scale, NOT an architecture scale! 16

Reading Topographic Lines 17 Plans Courtesy of the Low Impact Development Center, Inc.

Reading Topographic Markings Grading plans will show both existing and planned topography Elevations of contour lines are printed on the lines and are given in feet above sea level Elevations between contour lines remain between the elevations of the bounding contour lines 18

Reading a landscape plan 19 Plans Courtesy of the Low Impact Development Center, Inc.

Understanding plant schedules 20 Plans Courtesy of the Low Impact Development Center, Inc.

Working with Specifications Material specifications for bioretention cells are specific and detailed They must be adhered to as closely as possible If substitutions are necessary, they should be cleared by an engineer Unapproved material substitutions are a common cause of bioretention failure 21

Bioretention media Bioretention media used in DDOT projects should be mixed offsite by the soil supplier, NOT by the contractor 22

Construction Notifications Maintenance of Traffic Coordination with Prime or other subs Briefings and reporting Inspection Documentation Closeout/Punchlist 23

Notifications DDOE Miss Utility / District One Call DDOT if working in the right-of-way 24

Inspections The approved SWMP will contain a construction inspection schedule, which specifies the stages of construction at which DDOE will conduct inspections Work cannot proceed past the stage of construction triggering an inspection until DDOE has inspected and approved the work done Section 5.2 of the Guidebook contains detailed instructions for scheduling and conducting inspections 25

Inspections In general, inspections are usually required: –Before construction begins –During infiltration tests –After construction of temporary sediment controls and drainage –After excavation to subgrade –During installation of underdrains and standpipes –After construction is completed 26

Crew and Equipment Selection Level of supervision Skillset and overlap of skills Equipment malfunctions/substitutes Location and availability of equipment Mobilization 27

Crew Training Safety Reporting and documentation Sequencing Observation/inspection Interaction with public and client 28

Mobilization and Storage Hazardous materials Storage requirements and location (e.g. watering, covering..) Mobilization area Work times Coordination with other contractors Utility notification 29

Construction Sequencing Pre-construction inspection and documentation Utility coordination Notifications Mobilization Construction and inspection Punch list Closeout 30

Slide 31 Photos Courtesy of The Low Impact Development Center

Step 1 Stabilize the entire contributing drainage area, preferably with vegetation Have utilities mark locations of existing lines 32

District One Call (Miss Utility) or call 811http:// Allow 2 business days for utilities to be marked Hand digging required within 18 inches of marked utilities 33

Understanding Utility Markings There is a uniform color code for marking underground utility lines, which is consistent across the country Proposed Excavation Temporary Survey Markings Electric Power Lines, Cables, Conduit and Lighting Cables Gas, Oil, Steam, Petroleum or Gaseous Materials Communication, Alarm or Signal Lines, Cables or Conduit Potable Water Reclaimed Water, Irrigation and Slurry Lines Sewer and Drain Lines 34

Step 2 Pre-construction meeting –Designer, installer, and DDOE inspector –DDOE inspector with check that the boundaries of the drainage area and inlet elevations conform to the original design –Submit material certifications for aggregate, soil media, and geotextiles 35

Step 3 Install temporary erosion and sediment controls to divert stormwater during construction 36 Photo Courtesy of DDOT

Maintenance of Traffic 37 Identify a qualified safety officer Determine need for permits Traffic Control Devices Personnel needs – trained Flagger Call Miss Utility Notify DDOT 48 hours before work is to begin

Maintenance of Traffic 38 Notify neighbors of parking restrictions Repair any damage that occurs during operations at the site Refer to the DDOT Work Zone Temporary Traffic Control Manual for detailed information

Maintenance of Traffic 39 Traffic is to be guided clearly and safely around the work zone Traffic includes vehicles, bicycles and pedestrians Review the “Daily Checklist for Temporary Traffic Control” found in the DDOT manual

Maintenance of Traffic 40 The safety officer is responsible for ensuring the safety of the area The safety officer is authorized to halt work should a problem or deficiency occur All traffic control devices must be removed once work is complete

Maintenance of Traffic 41 Pedestrian safety includes: –Signs and other devices to guide pedestrians around the work area –Notify neighboring properties in advance –Maintain access to businesses –Maintain access for handicapped individuals –Pedestrians are to be protected

Step 4 Excavate pretreatment cells, if applicable 42

Step 5 Excavate the bioretention cell Work from the sides; do not allow heavy equipment within the bioretention cell 43

Step 6 Rip bottom soils to 6-12 inch depth if necessary 44

Step 7 Place filter fabric, if specified, on sides of bioretention cell. Overlap sides by 6 inches. Place stone for storage layer, perforated underdrain pipe, stone diaphragm, choking layer, and permeable geotextile layers as specified. 45

Step 8 Place approved bioretention media Apply in 12-inch lifts to desired top elevation Allow media to settle for a few days, then add media as needed 46

Add media in 12” lifts Thoroughly wet and allow soil to drain Make sure the media is at specified height below overflow Bioretention: Media Placement Photo Courtesy of the Low Impact Development Center, Inc. 47

Step 9 Install trees and shrubs Follow the planting plan! Install temporary irrigation, if used 48

Slide 49 Follow the landscaping plan Incorporate the plan into maintenance Modify plan when plants are added, replaced, or removed Landscaping Plan Graphic Courtesy of the Low Impact Development Center, Inc.

Step 10 Install surface cover –Mulch to 3” depth –River stone at inlet, if specified 50

Step 11 Install herbaceous plant materials Follow the planting plan! Water as needed for the first two months of establishment 51

Step 12 Once drainage area and side slopes have good vegetative cover, unblock any blocked curb cuts or inlets, and remove erosion controls 52

Keep Erosion Controls in Place Until Drainage Area is Stabilized Irving St Images P & P Photos Courtesy of the Low Impact Development Center, Inc.

Step 13 Conduct final construction inspection Provide as-built certification to DDOE Submit GPS coordinates for each bioretention facility to DDOE for entry into their maintenance tracking database 54

55 Photo Courtesy of NC Cooperative Extension, NC State University

56 Photo Courtesy of NC Cooperative Extension, NC State University

57 Photo Courtesy of NC Cooperative Extension, NC State University

58 Photo Courtesy of NC Cooperative Extension, NC State University

59 Photo Courtesy of NC State BAE Stormwater Engineering Group

60 Photo Courtesy of NC State BAE Stormwater Engineering Group

61 Photo Courtesy of NC Cooperative Extension, NC State University

62 Photo Courtesy of NC Cooperative Extension, NC State University

63 Photo Courtesy of NC Cooperative Extension, NC State University

64 Photo Courtesy of NC Cooperative Extension, NC State University

65 Photo Courtesy of NC Cooperative Extension, NC State University

66 Photo Courtesy of NC Cooperative Extension, NC State University

9,000 ft 2 Drainage Area Rain Garden (1,500 ft 2 ) Photo Courtesy of NC Cooperative Extension, NC State University

68 Photo Courtesy of NC Cooperative Extension, NC State University

69 Photo Courtesy of NC Cooperative Extension, NC State University

70 Photo Courtesy of NC Cooperative Extension, NC State University

71 Photo Courtesy of NC Cooperative Extension, NC State University

72 Principal (Mrs. Greene) Photo Courtesy of NC Cooperative Extension, NC State University

73 Photo Courtesy of NC Cooperative Extension, NC State University

74 Photo Courtesy of NC Cooperative Extension, NC State University

Common Construction Errors

Inadequate Erosion Control or Protection of BMP Areas Photo Courtesy of the Low Impact Development Center, Inc. 76

77 Keep Erosion Controls in Place Until Drainage Area is Stabilized Irving St Images P & P Photos Courtesy of the Low Impact Development Center, Inc.

78 Unapproved Material Substitutions Photo Courtesy of the Low Impact Development Center, Inc.

Plant Density Plant Location Photos Courtesy of the Low Impact Development Center, Inc. 79

80 Photo Courtesy of the Low Impact Development Center, Inc.

81 Photos Courtesy of the Low Impact Development Center, Inc.

Improper Pooling Depth & Drainage Photos Courtesy of the Low Impact Development Center, Inc. 82

Incorrect grading Lack of curb cuts Compaction sequencing and documentation “Rogue” materials Incorrect slopes Incorrect equiptment 83

Resolving Issues and Challenges Contract terms Document, Document, Document Scheduling Impacts Adjustments 84

Demobilization Timing of equipment removal and labor Punch lists Documentation Closeout procedures Suggest follow up visit and notification 85

Reporting and Records Materials receipts and certifications Procedures for omissions and substitutions Organization of pictures, as-builts, and logs Labor use and timesheets Subcontractors 86

Review There is no such thing as to much documentation Create a checklist for each project Conduct basic training project overview for each crew Document any potential conflict or problem Follow up with client and make recommendations on how to improve projects 87

Resources Miss Utility Damage Prevention Guide eventionGuide.pdf eventionGuide.pdf Low Impact Development (LID) Construction and Maintenance Guidance Manual, Version 1.0. DDOE ( District of Columbia Stormwater Management Guidebook ( 88