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One of the key features of this project is the environmental restorations that will be constructed in the Commerce Park area. These projects are subdivided into two types: floodplain improvements and shoreline stabilization. The discussion below refers to 3 categories of maps that can be accessed within this website. For more detail on any zone, click on the map's
purple text. Also note that
there are navigation links below each graphic - you may need to page down to see them. All maps and diagrams in this section courtesy of ENSR Floodplain ImprovementThese are intended to improve the natural capabilities of the soils and vegetation to absorb pollutants from stormwater prior to discharging to the river. Stormwater pollution is the nation’s final battlefront in reducing pollution to our waterways. After major rainstorms, water flowing off of roads, parking lots, and other impervious surfaces collects oils, greases, salts, bacteria, nutrients, and other pollutants, which flow to the nearest body of water. For new developments, structures can be designed to intercept and purify these pollutants to prevent waterways from receiving this pollution. For existing areas that have already been developed, this presents a challenge: retrofitting the existing drainage patterns in a manner that will reduce the normal pollutant loading. For this project, the City of Danbury hired a consultant, ENSR ( Northborough, MA) to analyze the options for retrofitting the existing drainage system in a manner that would reduce stormwater pollutants flowing from Route 6, Eagle Road, and parking areas adjoining the river corridor. ENSR initiated this work by conducting a computer model that estimated the capabilities of the floodplain for absorbing these pollutants. Since the floodplain is a flat area, the stormwater will discharge onto it, prior to flowing into the Still River. As this water sits on the floodplain, the pollutants from the roads and parking areas slowly settle out and are absorbed on the soil and vegetation of the floodplain. ENSR’s computer models determined that the natural capabilities of the floodplain are approximately 70 - 75% effective in reducing the pollutant loads prior to discharge to the Still River. This is good news, since this is close to the 80 % guideline that is promoted by the Environmental Protection for reduction of stormwater pollution. Nevertheless, there are measures that can improve the floodplain’s natural capabilities for absorbing this pollution. ENSR’s designs for stormwater attenuation will modify the floodplain by raising the height of river levee with a mat of vegetation that will allow the area to hold more stormwater for a longer period and provide more time for the pollutants to settle out. The natural levees along the banks of the river (which can be likened to the lip of a bowl) hold water that flows from developed areas during rain storms. Planting coconut fiber mats of vegetation along the River levees will have the effect of “increasing the depth of the bowl.” Other measures involve the placement of “check dams” along strategic drainage points, which will act to slow down stormwater (allowing better pollutant settlement) prior to discharge to the river and placing stone pads just prior to the discharge outlet to the watercourse. The locations of all of these designs are illustrated on the Index Map. Shoreline StabilizationThis work involves a 100 foot section that is identified on the Index Map and the Site Detail Map of Zone 2. The Stabilization work is designed to create a shallow quiet water zone that will provide cover, shading, and hiding areas for fish. This will further enhance the fish habitat of the project corridor, capitalizing on the recent improvements that have been noted by the DEP fish surveys. The approach for achieving this is a design referred to as a “Tree Trunk Revetment” project. This work, which can be accessed by clicking on the tree icons on the Detail Work Plan Map for Zone 2, involves cutting down 10 - 12 trees that are 1 foot in diameter and leaving their root wads intact. These trunks will be taken to the location labeled “Shoreline Stabilization Area” on the Index Map and the Design Detail maps. They will then be anchored lengthwise to the shoreline and joined together for a 100 foot stretch, with the root wads facing upstream. The end result of this stabilization project is exhibited on the two schematic drawings that can be viewed by clicking on the tree trunk icons that are on the Detailed Design Drawings for Zone 2. Finally, live willow cuttings will be placed in the embankment above the tree trunks, to provide further shading and habitat structure. This design will provide the following habitat improvements :
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