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Stormwater BMP Design

 

The project involved design of a stormwater best management practice (BMP) for capture and treatment of post-construction stormwater runoff from a commercial development in Brunswick County, North Carolina. The stormwater BMP was designed pursuant to the requirements outlined in the North Carolina’s Coastal Stormwater Regulations and the Brunswick County Stormwater Regulations, and because post construction built-upon area exceeded 30% of the total developed area and post-development peak runoff exceeded pre-development peak runoff from a 1-year, 24-hour storm.

Stormwater runoff from the site’s impervious surfaces (roofs, parking lots, and vehicle and pedestrian travel areas) and a portion of the off-site drainage areas (existing roadways) was designed to be through surface and subsurface conveyance measures (curb-and gutter) and finished surface grade into two (2) subsurface infiltration trench systems installed on the northern and southern corners of the property. Each infiltration trench system was designed to capture and treat the first 1.5 inches of stormwater runoff from its respective drainage area, in accordance with State Coastal Stormwater Management requirements. Runoff in excess of the first 1.5 inches was designed to be routed via sheet surface flow into vegetated ditches constructed within the Right-of-Ways along the southern property line.

Each infiltration trench system consisted of ADS 30-inch diameter perforated piping. The piping was installed in a row-like fashion and manifolded into a header at the inlet end of each trench. The piping was installed on a bed of 10-inches of washed stone with a 2-inch thick stone covering. A 12-inch stone border was placed along the outer perimeter of the chamber matrix, and the chambers and stone will be installed within a filter fabric liner, and covered with a minimum 2-inch layer of compacted fill and 2 inches of asphalt pavement. The infiltration trenches were installed at a final depth of at least two feet above the seasonal high ground water table depth in accordance with State BMP requirements. The piping was designed with a traffic loading rating of ASHTO H-20 due to the thin layer of cover required to maintain final site grade and depth restrictions.

The stormwater management system was permitted through the North Carolina Division of Water Quality and Brunswick County, and was installed in the Fall of 2007.

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Latest News at Duncklee & Dunham
 

August  2010

Rodak Engineering has merged into Duncklee & Dunham.  As a result, Duncklee & Dunham now offers engineering services such as air pollution control design and permitting, stormwater design permitting and monitoring, wastewater system design, point of entry treatment system design and construction, soil and groundwater treatment system design, and environmental compliance auditing and management system support.  For more information about our engineering services, please contact Andy Rodak, PE at andy@dunckleedunham.com .

May 2010

Duncklee & Dunham has been a NC DENR Registered Environmental Consultant (REC) since 1998 and has three DENR approved Registered Site Managers (RSMs) under the REC Program. Duncklee & Dunham RSMs are managing four active REC site projects involving metal, chlorinated solvent, and nutrient contamination in soil and ground water.

February  2010

Dave Duncklee, Tom Dunham, Daphne Jones, and Bryson Trexler of Duncklee & Dunham and Andy Rodak of Rodak Engineering recently attended the 2010 Southeastern In Situ Soil and Groundwater Remediation Conference to maintain our edge in In Situ Chemical Oxidation (ISCO), In Situ Chemical Reduction (ISCR),  and bioaugmentation technologies. The technical presentations, as well as interfacing with other consultants, scientists, and regulators, proved to be valuable.

January  2010

Dave Duncklee remains active in the Association of Environmental and Engineering Geologists (AEG), currently serving as treasurer on the Carolinas Section board, as short course committee chair on the AEG Charleston 2010 national meeting, and as co-chair of the national AEG continuing education committee. Dave has also recently been approved by the Interstate Training and Regulatory Council (ITRC) to participate in the newly formed Environmental Molecular Diagnostics team.

November  2009

Duncklee & Dunham's Bryson Trexler is using innovative techniques to develop site specific soil clean-up levels and develop a ground water variance for site metals restoration. The site is under the REC program and currently being managed on a fast track basis to accommodate expedited clean-up of soil and groundwater once plant modifications are made.

Duncklee & Dunham is preparing to implement full scale injection plan involving sodium persulfate into shallow groundwater under and adjacent to a former manufacturing building. A corrective action plan and an injection permit were submitted and approved under the Ga EPD HSR program.

November  2009

Congratulations to Jayson Kilcoyne on his promotion to Project Environmental Scientist II. His efforts are currently concentrating on the assessment and remediation of agrichemical and petroleum UST projects.

October  2009

In partnership with a local law firm, Duncklee & Dunham has recently provided pro bono professional assistance to Hope Elementary Charter School in Raleigh, North Carolina. Work was conducted to assess and dispose approximately three tons of soil, potentially contaminated with lead-based paint, from the school property. The closure report was submitted to the school in October 2009.

April  2009

Duncklee & Dunham is performing our third GIS brownfield inventory project for a local NC municipality. This project is being performed for several hundred parcels and will be completed in approximately five weeks time start to finish.

March 2009

Duncklee & Dunham has completed a 1,700 parcel GIS brownfields inventory for a local NC municipality. Muti-parcel Phase I ESAs are currently being performed under this US EPA brownfields grant funded project. To our knowledge, this is the second GIS brownfields inventory completed in NC, both of which have been performed by the firm. Dr. Trexler is currently working with US EPA Region 4 to finalize a QAPP so that phase II assessment tasks can be implemented using the brownfield grant funds.

February 2009

In a joint effort with Rodak Engineering, Duncklee & Dunham is in the process of performing over one hundred SPCC plans across the US. Duncklee & Dunham has prepared over 900 spill plans across the US over the past ten years.

December  2008
 
Cary Office - Office renovations are complete and the Duncklee & Dunham office is back to a full house. Feel free to stop by and take a look. See the Contact page for a before and after photo!


 


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