Work on the project spans two academic semesters. We received the project in September 2023, and the final design package will be completed by May 2023.
A chart showing our planned milestones for the Fall Semester. Last updated December 6, 2023.
A summary of wetland configurations currently in use.
A report examining legal and engineering standards related to the project.
A summary of plant species used in wetland construction.
A chart showing our planned milestones for the Spring Semester. Last updated March 27, 2024.
A spreadsheet comparing plant prices from different online suppliers. We plan to update this file as we develop our wetland design.
Below depicts a flow accumulation map for our area of concern. As shown, flow accumulates along the purple lines throughout the map and runs to the water reservoir before flowing into the small stream (shown in pink). In general, it can be assumed from this map that runoff from the site does not accumulate/flow toward the potential wetland area and thus can be neglected for the sake of our concerns.
The following maps show potential locations/areas where the wetland could be constructed.
Based on current calculations without factors of safety, the minimum area for the wetland would be approximately 0.36 acres. Area 1 will be sufficient to reduce levels of BOD5 to within EPA limits even during cold seasons, and spans a level patch of land with no trees. This limits the cost of construction to minimal earthwork.
Area 2 shown here covers most of the available area between the existing treatment plant and the adjacent wooded area. It is twice the size of the minimum area to treat BOD5 as needed,
The areas presented here are based on reduction of BOD5. The team is currently calculating minimum sizing to treat other contaminants, such as E. coli and nitrate.
The following drawing shows the planned areas for a forebay, shallow pond, and planting areas. The inlet and outlet are also represented on this drawing.
Floating vegetation types to be utilized are water lily, water hyacinth, and duckweed.
Rooted plant types will include bulrush, common reed, and water willow.
We have created a wetland calculation workbook. The purpose of this excel sheet is to add to the body of knowledge in calculating wetland area, hydraulic loading rate and hydraulic residence time. These are important parameters to know for a wetland, and this workbook allows for easy access to calculate different scenarios for a wetland.
The maximum area of the wetland, 0.8 acres, is driven by the target nitrate concentration of 0.5 ppm for drinking water. We must remove 75% of nitrate in the effluent from wastewater treatment through the wetland. This can be achieved through a hydraulic retention time of 27 days and hydraulic loading rate of 1 cm per day. The above workbook shows the calculations used to reach these conclusions.
Below are preliminary cut and fill calculations/information for the wetland. The total volume of excavation includes the overall area times the average depth of the wetland (1010 cubic meters) as well as an additional anchor material for the wetland liner (470 cubic meters). In addition to this total volume the forebay and effluent micropool were found based on standard volume percentages These calculations will be further refined as the project model is developed in Civil 3D.
The following drawing shows the planned areas for a forebay at the inlet, micropool before the outlet, and meandering water flow path.
The following worksheet contains information on the plant species that are planted in the wetland. Each sheet contains pricing found from several different suppliers. The "Areas" tab contains the areas of each section, the plant varieties in each section, a count for the estimated number of each plant, and an estimated total cost for plant materials.
The following drawing shows the labeled updated areas, as well as the existing infrastructure in the surrounding area.
The following Bill of Materials includes our outlet structure (a stainless steel V-notch weir, our gravel inlet area, and updated planting estimates.
To determine an initial cut and fill volume for the wetland area using Civil 3D, a base surface was created and compared to the existing ground surface. The northernmost corner of the wetland, where the inlet will be, has an original elevation of 641.39’ and is at the highest elevation of the wetland area. The average depth of the wetland is 1’, so for earthworks calculations it was decided that the excavated elevation of the northernmost corner of the wetland would be 640.39’. Lateral bed slope is not a critical design parameter, but it should not exceed a 0.1’ difference from the inlet to the outlet, as large slopes can cause unwanted channels to form in the wetland and increase erosion. In light of this, the average slope along the bottom of the wetland was chosen as 1%, sloping downwards from the inlet. The banks of the wetland are constructed with a 3:1 slope, reducing the total water volume by a negligible amount. In the plan view image, the dark blue shows shallow cut areas while the light blue corresponds to deeper cut areas. The total area covered by the wetland is 41325.75 square feet, with the cut volume calculated as 8597.15 cubic yards. This value is greater than the volume found by hand calculations, due to the elevation difference the wetland spans.