update on odots l&d manual for post-construction control bmps mike wawszkiewicz, p.e....
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UPDATE ON ODOT’S L&D MANUAL FOR UPDATE ON ODOT’S L&D MANUAL FOR POST-CONSTRUCTION CONTROL BMP’SPOST-CONSTRUCTION CONTROL BMP’S
Mike Wawszkiewicz, P.E.◦Hydraulic/BMP Specialist, Central
Office Production
IntroductionIntroductionTopics
◦ 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?
IntroductionIntroductionMagnitude 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
ODOT/Storm Water ODOT/Storm Water AcronymsAcronyms 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
Linear Transportation Linear Transportation BMPsBMPs 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
Linear Transportation Linear Transportation BMPsBMPs
◦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
Linear Transportation Linear Transportation BMPsBMPsRural
Construction◦ Options are
limited Vegetated Biofilter Small Dry Detention
Areas
Urban Construction◦ Options are very
limited Manufactured
Systems Exfiltration Trench Underground
Storage
Linear Transportation Linear Transportation BMPsBMPsOhio 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. “
Linear Transportation Linear Transportation BMPsBMPsODOT and OEPA agreed that the
following alternative BMPs can be used for linear transportation projects:◦Manufactured System◦Vegetated Biofilter◦Exfiltration Trench
Linear Transportation Linear Transportation BMPsBMPsManufactured
Systems – Item 895◦ Filtering devices
that allow for treatment of a portion of the flow in a storm sewer
Note off-line configuration
Linear Transportation Linear Transportation BMPsBMPs
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
Design RequirementsDesign RequirementsODOT 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
Design RequirementsDesign RequirementsODOT 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
Design RequirementsDesign RequirementsNew 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
Design RequirementsDesign 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
Design RequirementsDesign 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)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 1115.6.1 and 1115.6.2
Design RequirementsDesign RequirementsRedevelopment: No increase to
runoff coefficient◦The area within existing ODOT R/W is
considered impervious area for the purpose of post-construction BMP calculations
Design RequirementsDesign RequirementsRedevelopment
◦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
Design RequirementsDesign RequirementsWhat does Redevelopment mean for
the amount of treatment required?◦ Localized Treatment: Provide 100%
treatment for an area equal to 20% of the Project EDAor
◦ 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 1115.6.1
Design RequirementsDesign 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.
Redevelopment – Vegetated Redevelopment – Vegetated BiofilterBiofilter
Redevelopment – Vegetated Redevelopment – Vegetated BiofilterBiofilterDesign Examples for vegetated
biofilters and exfiltration trenches can be found at the following website:◦http://www.dot.state.oh.us/
Divisions/ProdMgt/Production/bmp/Pages/PostConstructionBMP.aspx
Design RequirementsDesign 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)
Design RequirementsDesign 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 project
◦Discharging to 4th order stream◦Ultra-urban areas
Design RequirementsDesign RequirementsWater Quantity alternative options:
◦ Stream Protection based on culvert/bridge design Grade Controls for bridges and culverts L&D Volume 2, Section 1115.2 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
Design RequirementsDesign RequirementsNothing fits my project – What now?
◦ ODOT-Let Projects – Contact ODOT Central Office Production (Mike Wawszkiewicz)
◦ Local-Let Projects Contact Ohio EPA – District Contact http://www.epa.state.oh.us/dsw/storm/
contacts_storm.html
◦ 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
ODOT ExperiencesODOT ExperiencesConsider 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 ProjectsWhy?
◦ Construction Cost◦ R/W Cost and Acquisition Time
Especially Vegetated Biofilters◦ Maintenance Costs and Time to Maintain!!!!
ODOT ExperiencesODOT 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.
ODOT ExperiencesODOT 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
ODOT ExperiencesODOT ExperiencesConstructability
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
ODOT ExperiencesODOT ExperiencesMaintenance Issues
◦ Understand the materials/equipment/training needed for maintenance are available for the specified BMPs
◦ Disposal of BMP wastes…Hazardous?
Maintenance Maintenance ResponsibilitiesResponsibilities
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
Maintenance Maintenance ResponsibilitiesResponsibilitiesMaintenance 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.
Maintenance Maintenance ResponsibilitiesResponsibilitiesMaintenance 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
Maintenance Maintenance ResponsibilitiesResponsibilitiesODOT 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
Maintenance Maintenance ResponsibilitiesResponsibilitiesODOT 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
Permitting ResponsibilitiesPermitting ResponsibilitiesLocal-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.
What’s next?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…
Watershed Specific Watershed Specific PermitsPermits 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
Watershed Specific Watershed Specific PermitsPermits 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
Watershed Specific Watershed Specific PermitsPermitsOhio 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)
Watershed Specific Watershed Specific PermitsPermits“Mitigation for mitigation”
◦Overlapping Mitigation resulting from State or Federal environmental regulations (i.e. 404/401) may be adjusted in recognition of these requirements.
Watershed Specific Watershed Specific PermitsPermitsRedevelopment 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.
Watershed Specific Watershed Specific PermitsPermitsBig Darby and Olentangy were
generated by TMDL recommendations
More TMDL watersheds have potential to become Watershed Specific Permits.
Manufactured System
Vegetated Biofilter
Exfiltration Trench
Detention Basin
Questions?Questions?
Mike Wawszkiewicz, P.E.◦Phone: 614-728-4585◦Email:
◦ODOT Post-Construction BMP Website:http://www.dot.state.oh.us/Divisions/ProdMgt/Production/bmp/Pages/PostConstructionBMP.aspx