Mike Wawszkiewicz, P.E.

Transcription

1 UPDATE ON ODOT S L&D MANUAL FOR POST-CONSTRUCTION CONTROL BMP S Mike Wawszkiewicz, P.E. Hydraulic/BMP Specialist, Central Office Production

2 Introduction Topics Linear Transportation Post-Construction BMPs Differences from standard residential/commercial development Design Requirements Amount of Treatment ODOT Experiences Design, Construction, Maintenance Issues Maintenance and Permitting Responsibilities What s next?

3 Introduction Magnitude of Permitting Per OEPA database of Construction General Permit Permittees: ODOT has ~660 permits To ensure a consistent application regarding post-construction BMPs for roadway projects, ODOT needed to have design guidelines

4 ODOT/Storm Water Acronyms BMP Best Management Practice CGP Construction General Permit EBW Enhanced Bankfull Width EDA Earth Disturbed Area ExT Exfiltration Trench L&D Manual ODOT Location and Design Manual LPA Local Public Agency NOI Notice of Intent NPDES National Pollutant Discharge Elimination System OEPA Ohio Environmental Protection Agency SWPPP or SWP3 Storm Water Pollution Prevention Plan T% - Treatment Percent TSEC Temporary Sediment and Erosion Control VBF Vegetated Biofilter WQf Water Quality Flow WQv Water Quality Volume

5 Linear Transportation BMPs Linear Transportation Projects vs. Standard Land Development Difficulty implementing BMPs listed in the Construction General Permit R/W limitations (Eminent Domain) Safety of the traveling public Linear nature results in crossing multiple watersheds (centralized BMP impossible) Dangers of Ponded Water Multiple Watersheds Crossed

6 Linear Transportation BMPs Difficulty implementing BMPs listed in the Construction General Permit (cont.) Roadway improvements offer little ability to change alignment to allow easier BMP implementation. Not an option to relocate existing bridges and roads in most cases. Urban environments Highly developed areas with little room for storm water facilities Henderson Road Bridge

7 Linear Transportation BMPs Rural Construction Options are limited Vegetated Biofilter Small Dry Detention Areas Urban Construction Options are very limited Manufactured Systems Exfiltration Trench Underground Storage

8 Linear Transportation BMPs Ohio EPA Construction General Permit for Storm Water Discharge (OHC000003) Part III.G.2.e Post-Construction Storm Water Management Requirements Transportation Projects ODOT L&D Volume 2 The construction of new roads and roadway improvement projects by public entities (i.e., the state, counties, townships, cities, or villages) may implement post-construction BMPs in compliance with the current version (as of the effective date of this permit) of the Ohio Department of Transportation s Location and Design Manual, Volume Two Drainage Design that has been accepted by Ohio EPA as an alternative to the conditions of this permit.

9 Linear Transportation BMPs ODOT and OEPA agreed that the following alternative BMPs can be used for linear transportation projects: Manufactured System Vegetated Biofilter Exfiltration Trench

10 Linear Transportation BMPs Manufactured Systems Item 895 Filtering devices that allow for treatment of a portion of the flow in a storm sewer Note off-line configuration

11 Linear Transportation BMPs Exfiltration Trench Item 835 Pervious concrete layer at top allowing water to enter a 12 inch layer of filter material Standard Construction Drawing: WQ-1.3

12 Design Requirements ODOT Location & Design, Volume 2 Project Thresholds Earth Disturbed Area (EDA > 1 acre) Routine Maintenance Projects are exempt Projects that do not change original line, grade and hydraulic capacity of the facility (i.e. resurfacing) EDA < 5 acres List of maintenance activities in L&D Vol. 2, Section 1200

13 Design Requirements ODOT Location & Design, Volume 2 Project Classifications for Post-Construction Storm Water BMP Design Redevelopment vs. New Construction Redevelopment - 20% treatment required New Construction Treatment % (T%) required

14 Design Requirements New Construction New Construction does not necessarily mean a brand new highway alignment. Any project where pavement is added outside the existing R/W resulting in a change in the runoff coefficient. The area within existing ODOT R/W is considered impervious area for the purpose of post-construction BMP calculations Calculate Weighted Average of New Impervious vs. Existing Impervious to determine amount of treatment

15 Design Requirements New Construction New construction projects allow for a reduction of treatment based on the weighted average of existing vs. new impervious area in a drainage area or for a project (Treatment Percent) A brand new alignment project would require 100% treatment

16 Design Requirements What does New Construction mean for the amount of treatment required? Localized Treatment: 100% treatment for a specific area of the project (Area must be equal to T% x Project Earth Disturbed Area) or Project Wide Treatment: Provide reduced treatment for the entire project based on T% Allowable treatment reductions for specific BMPs (i.e. exfiltration trench), see L&D Vol. 2, Section and

17 Design Requirements Redevelopment: No increase to runoff coefficient The area within existing ODOT R/W is considered impervious area for the purpose of post-construction BMP calculations

18 Design Requirements Redevelopment Projects that do not add impervious area outside the existing R/W are considered redevelopment Includes most ultra-urban projects and divided highways that widen toward the median Widening toward the median would be considered redevelopment for this divided highway

19 Design Requirements What does Redevelopment mean for the amount of treatment required? Localized Treatment: Provide 100% treatment for an area equal to 20% of the Project EDA or Project Wide Treatment: Provide 20% treatment for the entire project Allowable treatment reductions for specific BMPs (i.e. exfiltration trench), see L&D Vol. 2, Section

20 Design Requirements When storm water treatment is being applied using a Localized Treatment : Credit toward meeting the treatment goal (% of EDA) is only applied to the portion of the contributing drainage area to the BMP within the roadway right-of-way (onsite). Any offsite contributing drainage area must be included in the BMP calculations for sizing purposes (i.e. width of ditch, length of ExT, etc.). The offsite area will not be included in the reduction of the required amount of project EDA that requires treatment.

21 Redevelopment Vegetated Biofilter

22 Redevelopment Vegetated Biofilter Design Examples for vegetated biofilters and exfiltration trenches can be found at the following website: Production/bmp/Pages/PostConstructionBMP. aspx

23 Design Requirements Water Quantity/Water Quality Differences Most linear BMPs treat water quality only Water quantity post-construction BMPs are typically detention facilities (difficult to fit in the linear transportation footprint)

24 Design Requirements Water Quantity (stream protection/stability) treatment not needed when: One or less acre of new impervious area is created in new permanent right-of -way area being acquired for the project Discharging to 4th order stream Ultra-urban areas

25 Design Requirements Water Quantity alternative options: Stream Protection based on culvert/bridge design Grade Controls for bridges and culverts L&D Volume 2, Section provides additional information for culvert design options that provide water quantity credit (i.e. concrete aprons, bankfull design) OEPA considers cutoff walls at culverts as a grade control

26 Design Requirements Nothing fits my project What now? ODOT-Let Projects Contact ODOT Central Office Production (Mike Wawszkiewicz) Local-Let Projects Contact Ohio EPA District Contact Possible Options at increased ratio (1.5:1 WQv) Offsite Mitigation Conservation Easements Offsite mitigation and conservation easements should be coordinated through Ohio EPA prior to NOI submittal

27 ODOT Experiences Consider the impacts of BMPs during plan development! Right-of-way Issues need to be identified early Take advantage of the treatment reductions allowed through the CGP and L&D Volume 2. Take the time to calculate the T%. Do not provide post-construction BMPs on Routine Maintenance Projects Why? Construction Cost R/W Cost and Acquisition Time Especially Vegetated Biofilters Maintenance Costs and Time to Maintain!!!!

28 ODOT Experiences Design Considerations Depth of BMP (manufactured system) Location of BMP for access. Vacuum trucks needed for manufactured systems. Confined Space issues Can one manufactured system replace long runs of Exfiltration Trench? The initial cost may be higher. However, for maintenance purposes, it may be more beneficial to use a single manufactured system.

29 ODOT Experiences Design Considerations (cont.) Detention Facilities: Consider the effects of ponding water on the upstream drainage system. Culvert tailwater effects Ditch flow depths Storm sewer capacity

30 ODOT Experiences Constructability Issues Utility Conflicts Maintaining BMPs free of construction debris (sequencing of construction activities) Condition of BMP at point of hand-off from construction to maintenance

31 ODOT Experiences Maintenance Issues Understand the materials/equipment/training needed for maintenance are available for the specified BMPs Disposal of BMP wastes Hazardous?

32 Maintenance Responsibilities Part IV.B.1 of CGP requires that a maintenance agreement is in place when filing the NOT ODOT will maintain BMPs on ODOT maintained roadways and facilities

33 Maintenance Responsibilities Maintenance Issues Where are the BMPs? ODOT is developing an inventory of post-construction BMPs on ODOT roadways Training of ODOT staff (County Managers) on maintenance procedures OEPA can audit MS4 s.

34 Maintenance Responsibilities Maintenance Issues Frequency for clean out of some linear BMPs is still unknown (i.e. Exfiltration Trench) Level of effort for some BMPs may be high based on frequency

35 Maintenance Responsibilities ODOT projects that extend onto Local Public Agency roadways Similar to other roadway features, ODOT will NOT maintain post-construction BMPs outside of ODOT right-of-way Local is responsible for maintenance Coordination during Preliminary Legislation development

36 Maintenance Responsibilities ODOT Projects extending onto LPA roadways Local may request a specific BMP type based on maintenance concerns ODOT may require Local to pay the difference in cost

37 Permitting Responsibilities Local-let LPA projects filed through ODOT Local agency files the NOI The LPA is responsible for providing post-construction BMP that meet Ohio EPA expectations (may use L&D Volume 2 or other EPA approved guidance) The LPA, not ODOT, must coordinate with Ohio EPA if deficiencies are identified.

38 What s next? Watershed Specific Permits Big Darby Portions of the Olentangy ODOT Research Exfiltration Trench - Performance, Durability and Maintenance Vegetated Biofilter - Performance Refinements to existing BMPs and continued monitoring

39 Watershed Specific Permits Big Darby Counties affected: Logan, Champaign, Clark, Union, Madison, Franklin, Pickaway Effective Date: October 27, 2006 Riparian Setback and Groundwater Mitigation Sediment Pond size: 134 CY/Ac of drainage Total Suspended Solids testing 45 mg/l TSS performance required

40 Watershed Specific Permits Olentangy Counties affected: Morrow, Marion, Delaware, Franklin Issued: January 23, 2009 Effective Date: April 8, 2009 Riparian Setback Mitigation Sediment Pond size: Same as Standard CGP

41 Watershed Specific Permits Ohio EPA Requirements Submittal of SWPPP with NOI application ODOT submits temporary sediment basin locations, post-construction BMP locations, and mitigation calculations. Contractor completes remainder of SWPPP when project is awarded. 45-day review period (standard CGP is 21 day review)

42 Watershed Specific Permits Mitigation for mitigation Overlapping Mitigation resulting from State or Federal environmental regulations (i.e. 404/401) may be adjusted in recognition of these requirements.

43 Watershed Specific Permits Redevelopment Projects covered by Watershed Specific Permits Projects located within the delineated setback boundary are exempt from Riparian Setback Mitigation provided the proposed project does not further intrude the delineated setback boundary.

44 Watershed Specific Permits Big Darby and Olentangy were generated by TMDL recommendations More TMDL watersheds have potential to become Watershed Specific Permits.

45 Detention Basin Exfiltration Trench Vegetated Biofilter Manufactured System

46 Questions? Mike Wawszkiewicz, P.E. Phone: ODOT Post-Construction BMP Website: uction/bmp/pages/postconstructionbmp.aspx