Presentation on theme: "UPDATE ON ODOT’S L&D MANUAL FOR POST-CONSTRUCTION CONTROL BMP’S"— Presentation transcript:
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 developmentDesign RequirementsAmount of TreatmentODOT ExperiencesDesign, Construction, Maintenance IssuesMaintenance and Permitting ResponsibilitiesWhat’s next?Focus on Linear BMPs. Other BMPs in L&D Manual, but used less frequently.How much treatment is needed to meet the permit? Redevelopment and other options that allow reductions.
3 Introduction Magnitude of Permitting Per OEPA database of Construction General Permit Permittees:ODOT has ~660 permitsTo ensure a consistent application regarding post-construction BMPs for roadway projects, ODOT needed to have design guidelinesOEPA staff not capable of covering every project. However, our responsibility to meet the Permit.Therefore, ODOT needs consistent guidance (L&D Volume 2)
4 ODOT/Storm Water Acronyms BMP – Best Management PracticeCGP – Construction General PermitEBW – Enhanced Bankfull WidthEDA – Earth Disturbed AreaExT – Exfiltration TrenchL&D Manual – ODOT Location and Design ManualLPA – Local Public AgencyNOI – Notice of IntentNPDES – National Pollutant Discharge Elimination SystemOEPA – Ohio Environmental Protection AgencySWPPP or SWP3 – Storm Water Pollution Prevention PlanT% - Treatment PercentTSEC – Temporary Sediment and Erosion ControlVBF – Vegetated BiofilterWQf – Water Quality FlowWQv – Water Quality VolumeOne of the most confusing things can be the acronyms/terminology.
5 Linear Transportation BMPs Linear Transportation Projects vs. Standard Land DevelopmentDifficulty implementing BMPs listed in the Construction General PermitR/W limitations (Eminent Domain)Safety of the traveling publicLinear nature results in crossing multiple watersheds (centralized BMP impossible)Dangers of Ponded WaterR/W limitations – Avoid total takes and other major impacts to adjacent properties.Dublin has had bad experiences. Two unfortunate accidents. Emphasizes the need to be careful regardless of following design standards. L&D Volume 1 ( Obstacles) states that protection should be provided for any body of water with a normal depth greater than one foot depending on the likelihood of encroachment. Bottom line: Be conservative with standing 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 facilitiesImprovements to Henderson Road Bridge in Franklin County would be a lot easier if we removed it from an urban setting with less traffic. Not possible.Henderson Road Bridge
7 Linear Transportation BMPs Rural ConstructionOptions are limitedVegetated BiofilterSmall Dry Detention AreasUrban ConstructionOptions are very limitedManufactured SystemsExfiltration TrenchUnderground StorageStarted career prior to ODOT in Land Development (no problem).Moved to ODOT. Roadway hydraulics. Did not expect to be focused on water quality, but that was a primary focus.Rural: Not the best picture, but shows opportunity for vegetated biofilters in ditches or small dry detention at ramps.Urban shows the potential problems with using underground features. Very difficult implementation.
8 Linear Transportation BMPs Ohio EPA Construction General Permit for Storm Water Discharge (OHC000003)Part III.G.2.e – Post-Construction Storm Water Management RequirementsTransportation 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 SystemVegetated BiofilterExfiltration TrenchManufactured System (ODOT has a Qualified Products List)Vegetated Biofilter and Exfiltration Trench – both are currently being researched to verify benefits and improve design criteria.
10 Linear Transportation BMPs Manufactured Systems – Item 895Filtering devices that allow for treatment of a portion of the flow in a storm sewerBig item, big construction cost, and potentially difficult maintenance (depth, equipment).As stated earlier, QPL maintained by Office of Materials ManagementNote off-line configuration
11 Linear Transportation BMPs Exfiltration Trench – Item 835Pervious concrete layer at top allowing water to enter a 12 inch layer of filter materialStandard Construction Drawing: WQ-1.3Filtering device.Typo on the filter media.
12 Design Requirements ODOT Location & Design, Volume 2 Project ThresholdsEarth Disturbed Area (EDA > 1 acre)Routine Maintenance Projects are exemptProjects that do not change original line, grade and hydraulic capacity of the facility (i.e. resurfacing)EDA < 5 acresList 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 DesignRedevelopment vs. New ConstructionRedevelopment - 20% treatment requiredNew 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 calculationsCalculate 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 RequirementsWhat 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)orProject 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 redevelopmentIncludes most ultra-urban projects and divided highways that widen toward the medianWidening toward the median would be considered redevelopment for this divided highway
19 Design RequirementsWhat does Redevelopment mean for the amount of treatment required?Localized Treatment: Provide 100% treatment for an area equal to 20% of the Project EDAorProject Wide Treatment: Provide 20% treatment for the entire projectAllowable treatment reductions for specific BMPs (i.e. exfiltration trench), see L&D Vol. 2, Section“project wide” essentially means centralized treatment. As discussed previously, difficult on linear transportation.
20 Design RequirementsWhen 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 (on- site).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.You might end up with a BMP that is treating offsite flows if you cannot divert them. However, it may be the only location suitable for a BMP. Therefore, it is your best option.
21 Redevelopment – Vegetated Biofilter Project EDA: 3 acres20% Project EDA: 0.6 acresArea 1 and 2 exceed the 0.6 acres. Therefore if the ditch is sized appropriately, either of these ditches would be adequate.Area #3 is only 0.2 acres. Therefore, not enough.
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 onlyWater quantity post-construction BMPs are typically detention facilities (difficult to fit in the linear transportation footprint)
24 Design RequirementsWater 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 projectDischarging to 4th order streamUltra-urban areas
25 OEPA considers cutoff walls at culverts as a grade control Design RequirementsWater Quantity alternative options:Stream Protection based on culvert/bridge designGrade Controls for bridges and culvertsL&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 ContactPossible Options at increased ratio (1.5:1 – WQv)Offsite MitigationConservation EasementsOffsite 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 earlyTake 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 ProjectsWhy?Construction CostR/W Cost and Acquisition TimeEspecially Vegetated BiofiltersMaintenance Costs and Time to Maintain!!!!How much
28 ODOT Experiences Design Considerations Depth of BMP (manufactured system)Location of BMP for access. Vacuum trucks needed for manufactured systems.Confined Space issuesCan 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 effectsDitch flow depthsStorm 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 maintenanceWhat’s wrong with this picture? TSEC issues? What options are there for protection?Utilities aren’t very precisely marked. If you only have 6” clearance, you might not have enough room unless you have very good SUE.
31 ODOT Experiences Maintenance Issues Understand the materials/equipment/training needed for maintenance are available for the specified BMPsDisposal of BMP wastes…Hazardous?
32 Maintenance Responsibilities Part IV.B.1 of CGP requires that a maintenance agreement is in place when filing the NOTODOT will maintain BMPs on ODOT maintained roadways and facilities
33 Maintenance Responsibilities Maintenance IssuesWhere are the BMPs? ODOT is developing an inventory of post-construction BMPs on ODOT roadwaysTraining of ODOT staff (County Managers) on maintenance proceduresOEPA can audit MS4’s.
34 Maintenance Responsibilities Maintenance IssuesFrequency 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 roadwaysSimilar to other roadway features, ODOT will NOT maintain post-construction BMPs outside of ODOT right-of-wayLocal is responsible for maintenanceCoordination during Preliminary Legislation development
36 Maintenance Responsibilities ODOT Projects extending onto LPA roadwaysLocal may request a specific BMP type based on maintenance concernsODOT may require Local to pay the difference in cost
37 Permitting Responsibilities Local-let LPA projects filed through ODOTLocal agency files the NOIThe 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 ODOT Research Big DarbyPortions of the OlentangyODOT ResearchExfiltration Trench - Performance, Durability and MaintenanceVegetated Biofilter - PerformanceRefinements to existing BMPs and continued monitoring…
39 Watershed Specific Permits Big DarbyCounties affected: Logan, Champaign, Clark, Union, Madison, Franklin, PickawayEffective Date: October 27, 2006Riparian Setback and Groundwater MitigationSediment Pond size: 134 CY/Ac of drainageTotal Suspended Solids testing45 mg/l TSS performance required
40 Watershed Specific Permits OlentangyCounties affected: Morrow, Marion, Delaware, FranklinIssued: January 23, 2009Effective Date: April 8, 2009Riparian Setback MitigationSediment Pond size: Same as Standard CGP
41 Watershed Specific Permits Ohio EPA RequirementsSubmittal of SWPPP with NOI applicationODOT 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 PermitsProjects 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 recommendationsMore TMDL watersheds have potential to become Watershed Specific Permits.
45 Detention BasinExfiltration TrenchVegetated BiofilterManufactured System
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