DEPARTMENT OF TRANSPORTATION

DISTRICT OF COLUMBIADEPARTMENT OF TRANSPORTATIONGREEN INFRASTRUCTURESTANDARDS2014

DISTRICT OF COLUMBIADEPARTMENT OF TRANSPORTATIONGREEN INFRASTRUCTURE STANDARDSSUPPLEMENT TO DESIGN AND ENGINEERING MANUALSUPPLEMENT TO STANDARD DRAWINGSSUPPLEMENT TO STANDARD SPECIFICATION FOR HIGHWAYSAND STRUCTURESGREEN INFRASTRUCTURE PLANT LISTGREEN INFRASTRUCTURE MAINTENANCE SCHEDULES2014

DISTRICT OF COLUMBIADEPARTMENT OF TRANSPORTATIONTERRY BELLAMY, DIRECTORRONALDO T. NICHOLSON, P.E., CHIEF ENGINEERMUHAMMED KHALID, P.E., DEPUTY CHIEF ENGINEERRAVINDRA GANVIR, P.E., DEPUTY CHIEF ENGINEERWASI KHAN, P.E., CHIEF QA/QC DIVISION

Green Infrastructure Standards Development TeamDDOT/IPMA/StormwaterMeredith Upchurch, ASLACarmen Franks, Ph.D.Alit BalkReginald Arno, P.E.Kyle Ohlson, P.E.DDOT/Urban ForestryJohn ThomasSharon DendyEarl EutslerJoseph BurckleDDOT/IPMA/QA-QCWasi Khan, P.E.Rezene Medhani, Ph.D., P.E.Larry ChungAlbert LadipohDDOT/IPMARichard Kenney, P.E.Adil Rizvi, P.E.DDOT/Active Transportation BranchJim Sebastian, AICPGeorge BranyanHeather DeutschDistrict Department Of EnvironmentRebecca StackSteve SaariGreg Hoffmann, P.E., Center for Watershed ProtectionA Morton ThomasLaura Mehiel, P.E.Don Rissmeyer, P.E.Steve Torgerson, RLA, ASLALarry G. Trout, Jr., P.E.Robert Pine, P.E., FASLA, Pine & Swallow

TABLE OF CONTENTSSUPPLEMENT TO DESIGN AND ENGINEERING MANUALCHAPTER 2 PROJECT DEVELOPMENT . D-12.3 Project Design Requirements D-12.3.10 Soil Erosion and Sediment Control and Stormwater Management . .D-12.3.11 Submittals . D-32.3.11.1 Preliminary Plan Submittal – 30% Review D-32.3.11.1.9 Stormwater Management Plan Submission at 30% Design Phase . D-42.3.11.2 Intermediate (Pre-Final) Plan Submittal – 65% Review . . . D-52.3.11.2.9 Stormwater Management Plan Submission at 65% Design Phase . . D-62.3.11.3 Final Construction Plans, Specifications, and Cost Estimates – Final Review . D-82.4 Preparation of Drawings . . . D-82.4.3 Description and Contents of Drawings . . D-82.4.3.16 Landscape and Planting Plans . . D-82.4.3.37 Stormwater Management Plan and BMP Design Submittal Requirements . D-9CHAPTER 33 ROADWAY DRAINAGE . . D-1033.14 Green Infrastructure/Low Impact Development Stormwater Management . .D-1033.14.1 General . . D-1033.14.2 Authority . D-1033.14.3 Design Guidance . . D-1033.14.4 Permeable Pavement . D-1133.14.5 Bioretention . .D-1633.14.6 Utility Clearances at LID Facilities . .D-21CHAPTER 47 LANDSCAPE DESIGN CRITERIA . . D-2347.7 Tree Space Design . D-2347.8 Planting Guidance for Vegetated Stormwater Systems . D-27SUPPLEMENT TO STANDARD DRAWINGSPERMEABLE PAVEMENT SERIES621.01Pervious Concrete Pavement (Roadway and Alley)621.02Pervious Concrete Sidewalk621.03Porous Asphalt Pavement (Roadway and Alley)621.04Porous Asphalt Sidewalk621.05Permeable Interlocking Unit Paver Pavement (Roadway and Alley)621.06Permeable Paver Sidewalki

621.10Permeable Pavement Elevation – 1621.11Permeable Pavement Elevation – 2621.12Permeable Pavement Edge RestraintBIORETENTION SERIES621.20Bioretention in Open Area621.21Bioswale Adjacent to Roadway621.22Bioretention Planter Adjacent to Roadway 1 – No Step Out Zone621.23Bioretention Planter Adjacent to Roadway 2 – With Step Out Zone621.24Curb Extension In-Planting Strip Bioretention621.25Curb Extension In-Street Bioretention621.30Bioretention Facility Street Side Edge Treatment -1621.31Bioretention Facility Street Side Edge Treatment -2621.32Bioretention Facility Sidewalk Side Edge Treatment621.40Inlet and Outlet for Curb Extension Bioretention621.41Curb Cut with Splash Pad - 1621.42Curb Cut with Splash Pad - 2621.43Curb Cut Metal Trench Drain Cover - 1621.44Curb Cut Metal Trench Drain Cover - 2621.45Metal Plate over Curb CutFLOW CONVEYANCE SERIES621.50Overflow Riser with Beehive Grate621.51Stormwater Facility Underdrain Pipe Risers621.52Stormwater Facility Underdrain Bedding and Catch Basin ConnectionCHECK DAM SERIES621.60Concrete Check Dam621.61Rock Check Dams621.62Plastic Lumber Check Dam621.63Acrylic Sheet Check Dam621.64Alternate Permeable Pavement Check DamsTREE SPACE SERIESii621.70Structural Soil under Sidewalk – Covered Tree Space621.71Structural Soil under Sidewalk – Continuous Open Tree Space621.72Structural Soil under Sidewalk – Confined Open Tree Space621.73Structural Soil under Covered Tree Space Only621.74Tree Space Covered Soil Volume Subsurface Drainage Options621.75Covered Soil Volume 1 – Pervious Cover or Impervious Cover with Linear Grate621.76Covered Soil Volume 2 – Impervious Cover with Catch Basin621.77Tree Space Grate Catch Basin

SUPPLEMENT TO STANDARD SPECIFICATIONS FOR HIGHWAYS ANDSTRUCTURES621.01Aggregates for Stormwater Management S-1621.02Geosynthetics for Stormwater Management . .S-7621.03Underdrains for Stormwater Facilities . .S-12621.04Pervious Concrete Pavement . S-16621.05Porous Asphalt Pavement . .S-25621.06Permeable Unit Paver Pavement . .S-34621.07Porous Flexible Pavement . S-40621.08Porous Grass Paving . .S-44621.09Bioretention, Plant Bed, Lawn and Sand Based Structural Soils . .S-47621.10Triple Shredded Hardwood Mulch . .S-6 621.11Curb Cut Metal Trench Drain Cover . S-6 621.12Domed Overflow Riser . .S-64621.13Check Dams for Stormwater Facilities . .S-65621.14Sidewalk Linear Slot Drain . .S-68621.15Tree Space Grate Catch Basin . .S-69621.16CU Soil . .S-70621.17Lightweight Aggregate . .S-71621.18Structural Cells for Soil Rooting Volume . S-72GREEN INFRASTRUCTURE PLANT LISTGuide for Green Infrastructure Planting . .P-1Plants for Use in Bioretention .P-3Trees for Use in Public Space P-19GREEN INFRASTRUCTURE MAINTENANCE SCHEDULESPermeable Pavement .M-1Bioretention . M-2Tree Space . M-3iii

DISTRICT OF COLUMBIADEPARTMENT OF TRANSPORTATIONGREEN INFRASTRUCTURE STANDARDSSUPPLEMENT TO DESIGN AND ENGINEERING MANUAL2014

SUPPLEMENT TO DDOT DESIGN AND ENGINEERING MANUALDistrict of Columbia Department of Transportation Design and Engineering ManualThe sections provided in this Standards Manual are to supplement the existing Design andEngineering Manual. No sections of the current manual are deleted and no text is modified. Allsections herein are to follow any existing sections and text sequentially.Supplement To: CHAPTER 2PROJECT DEVELOPMENT2.3 Project Design Requirements2.3.10 Soil Erosion and Sediment Control and Stormwater Management2.3.10.1 Stormwater Management Permit Requirements - Designing to the MaximumExtent PracticableProjects within the Public Right of Way are required to implement stormwater retention inaccordance with District Stormwater regulations to the Maximum Extent Practicable (MEP).This process must be a serious attempt to comply, considering every opportunity to achievethe full retention of the regulated stormwater volume. Construction projects in the Right ofWay are faced with a multitude of unique site constraints that vary widely. Limited spaceoutside of the roadway restricts opportunities for infiltration and evapotranspiration, and inmany cases the width of the roadway cannot be reduced to create additional space. Thespecific steps that must be explored for MEP design are stipulated in the DDOE StormwaterGuidebook, and include: Identify Drainage Areas and Calculate Stormwater Retention Volume (SWRv)Evaluate InfiltrationDemonstrate Full Consideration of Opportunities with Existing InfrastructureDemonstrate Full Consideration of Land Cover Conversions and Optimum BMPPlacementSize BMPsAddress Drainage Areas where Zero-Retention Practices are Installed (i.e. noretention is achieved)The DDOE Stormwater Guidebook defines the applicability of the design steps describedbelow to DDOT Public Right of Way projects, and/or to parcel development projects thatreconstruct the adjacent existing Public Right of Way as portion of the project (Type 1 andType 2 projects, respectively).D-1

SUPPLEMENT TO DDOT DESIGN AND ENGINEERING MANUAL2.3.10.2 Stormwater Management SubmissionsStormwater Management Plan (SWMP) submissions will be made with the 30%, 65%, 90%,and Final (100%) Design packages. The SWMP will contain a stormwater managementmap (SMM), MEP Worksheet, and Project Narrative as further in the Design Process section.The submissions will include increasingly more detail commensurate with the design stage.The SWMP is first submitted at the DCRA Permit Intake Center with a Building Permitapplication at 30% design. At DCRA, the SWMP is given to the DDOE technician forfurther detailed plan review. Each design phase SWMP will be submitted to the DDOETechnician at the DCRA Permit Intake Center. The timing of the submission should bewithin 2 weeks of the design plan milestone submission to DDOT. The submission will bereviewed by the DDOT project manager prior to submission at the Intake Center. DDOEplan review may take 10-30 business days.2.3.10.3 Design Process for MEPPrior to Project Design:Before the project reaches the design stage, the following items will be identified andincorporated into the Designer’s scope of work:a. Level of Disturbance: the level of disturbance will determine whether or not the retentionregulation applies to the project.b. Ownership of Land Adjacent to Right of Way: Projects must identify public lands andpublic rights of way adjacent to the project’s limit of disturbance. DDOT will consultwith adjacent public property owners and managers to evaluate opportunities to directstormwater runoff from the project drainage area to adjacent public lands. (This stepapplies only to DDOT projects, not to parcel projects which include construction withinthe Right of Way).c. Feasibility to Use Public Parking Zone: DDOT will define whether or not the PublicParking areas (between the sidewalk zone and the right of way line) are feasible for BMPplacement or land conversion.d. Feasibility to Use “Paper Streets”, “paper alleys”, and adjacent traffic islands: Anyundeveloped or green space right-of-way within or adjacent to the limits of disturbance ofpublic Right of Way projects will be evaluated for stormwater retention opportunitiesprior to design.Planning Phase:During the planning phase of a project, areas for stormwater retention should be identified tothe planning project level of detail. The steps in 30% design phase should be used toaccomplish as much advanced planning as the project allows. Steps that may be appropriatein the planning phase are: identifying available space, safe access issues, pedestriancirculation requirements, impervious surface removal, location of existing utilities, existingD-2