Storm Water Drainage Study, Improvements Evaluations, System Design and Construction
Braintree, MA
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Key Project Elements:
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Project Description:
ES&M was retained to characterize storm water flows, analyze existing operations, and propose improvements for a 62-acre bulk storage terminal (and former refinery). We segmented the site into seven areas, and determined specific parameters and objectives for each. We conducted detailed inspections to understand the existing storm water drainage system and where it was vulnerable to compliance problems, and we calculated/modeled drainage for four distinct segments of the site. We then drafted a conceptual plan and prioritized the needed improvements. In the loading rack area of the facility, it was critical to separate the contact water from non-contact water to minimize the volume of water requiring treatment. Once the contact water area was defined, we designed a drainage and separator system to treat the water to assure compliance with the facility’s discharge permit. In the bulk storage portion of the site, we again carefully segregated contact/non-contact water to minimize treatment. A significant portion of the property was deemed non-contact, and we created a separate discharge area for that water. By using Best Management Practices (BMPs), we fulfilled Massachusetts' storm water requirements and avoided a new compliance point for the customer. Most of the storm water for this large facility flowed through an outdated separator that was originally part of the historic refinery, and was not designed to remove Total Suspended Solids (among other constituents) to meet current NPDES permits. We designed a sediment removal/oil water separator system that could handle the anticipated storm flows while ensuring permit compliance. This system included a large Vortex unit and two parallel separators, with piping connections designed to allow for easy maintenance. We oversaw the installation and provided extensive soil and groundwater management services during construction. The final step in this large project was the decommissioning of the historic separator, and restoration of the area between the new structures and the water front. Since the structure was within a resource area, we procured the applicable permits and oversaw the site work. We utilized excess soil from the site (using an open-ended RAM Plan) to fill the structure, making sure to allow for adequate drainage. We also designed and oversaw the construction of the new road with appropriate drainage. |