• Work in conjunction with Municipal Engineering Departments to determine viable outfall retrofit sites for bio-retention systems.
• Assist in 319 grant writing.
• Provide support for local and state permitting.

• Provide engineered plans, hydrological analysis, structural certification, and materials specifications for the Bio-Retention Systems and collector areas.

In conformance with all procurement and labor laws, environmental order of conditions, local / state road & drainage regulations, and local / state building codes, we would work in either of two capacities:

Work in conjunction with Public Works staff to purchase and place all elements of the construction retrofit project. This would provide “in kind” 319 Grant match responsibilities, or provide a reduced cost to Municipalities for NPDES projects.

Or, assume all the responsibility to purchase and place all elements of the construction retrofit project.

Plant material is used as a filtration medium along with a Bio-retention Soil Mix (BSM) and organic layering. After the swale is constructed, the plant material requires proper hydration until root zones are fully established.

The swale component in the struture can be subject to washout in flash flood conditions, before root zones are fully established. Washouts would be re-packed with root zone mix and replanted. In newly planted swales, the bypass culvert gate may be used to dissipate flash flood conditions.

The bio-retention system captures Total Suspended Solids from influent flows that pass beyond conventional sump structures. If the siltation layer becomes too thick, it will choke out the plant material. Annual Maintenance includes removal of the siltation layer back to the original root zone mix. A minimum of 80% removal of TSS from influent flows would be the benchmark in the Operating Management Plan. Actual TSS removal percentage should be in the 90% level.

Conditions can be harsh and can vary greatly from site to site. Plant species may not always perform well in specific environments and may need to be replaced with a different species or varietals. Plant material may need periodic cutting, division, or may need intermittent low level organic fertilization.

Municipal Staff would determine the need or the desired level of monitoring. As a monitoring benchmark, annual soil samples would be collected and tested for concentrations of Sodium (NA), Dissolved Inorganic Nitrogen (DIN), Total Phosphorus (TP), ph, Total Petroleum Hydrocarbons in the Diesel range (TPH-D), and dissolved metals specifically Total Zinc (ZN). Influent and Effluent water samples would be tested for: TSS, DIN, TP, TPH-D, ZN, ph, and Hydrogen ions.

Photos are taken to monitor plant growth, density, and seasonal effect. They are also used to demonstrate Storm Water Management Phase II compliance.