GZA GeoEnvironmental, Inc.

Scope Of Work

GZA's Chicago subsidiary, Huff & Huff (H&H), assisted Citgo with design and installation of rain gardens for stormwater management, which is consistent with the National Pollutant Discharge Elimination System (NPDES) Stormwater Permit requirements.  Prior to rain garden design, a feasibility analysis was completed, which estimated the runoff volume from the proposed area to be drained to the rain gardens from a model storm event.  The feasibility analysis also determined the rain garden size to handle select storm events. 

Conceptual designs were presented to Citgo, which included the on-site layout of the rain gardens, cross sections, landscape concept design, and cost estimate.  Final drawings of the preferred concept plan were presented to Citgo, suitable for construction, with a detailed planting schedule.  H&H coordinated with the plant supplier and a provided a biologist to oversee installation.

The rain gardens were installed with the use of Citgo and Huff & Huff volunteers.  The installed rain garden will result in reduced flooding, stormwater runoff treatment, and will provide an aesthetic appeal to employees of Citgo as well as the community. 

H&H created an Operation and Management (O&M) plan for the rain garden. The O&M Plan is to ensure the long-term viability of the completed rain garden. Specifically, the O&M Plan clearly outlined all management activities required for the long-term care of the rain garden.  

H&H also provided an education pamphlet and display panel in digital form as well as prepared quotes for signage to place adjacent to the rain garden for purposes of educating both the public as well as Citgo employees about the importance and function of rain gardens.