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<br />City of Centerville <br />Hidden Spring Park <br /> <br />Page 2 <br />September 26 2007 <br /> <br />5. The City wondered if the hydrant could be used to test how long it takes for the raingarden to <br />empty. <br />a. Following the September 10th meeting when this issue was brought up, the area received. <br />substantial rain. Jeff McDowell visited the raingarden approximately 24 hours after the <br />rain event. Wood chips along the side of the raingarden clearly showed the raingarden <br />had filled to capacity. The water level had dropped approximately 12 inches within those <br />24 hours, and the draintile was flowing slow and steady. This information was forwarded <br />to Gregg Thompson, and he responded by saying the drain-down times seemed good to <br />him (see attached email chain). <br />b. If the City would like a more controlled drain-down test, Bonestroo will use the hydrant to <br />fill the raingarden and time how long it takes to empty. <br />6. Can the raingarden sand/compost mix be tested to show compliance with the design? <br />a. Remedy - Gregg Thompson visited the site and used a penetrometer to test the <br />raingarden soils. He was able to easily push in the penetrometer to its full depth of 30". <br />Gregg responded that the soils" appear to be in really good shape". In addition, Veit has <br />submitted the raingarden soil mix tickets from Plaistads. See attached email <br />correspondence and tickets. <br />b. Timeline - COMPLETED <br />7. Can we verify that the raingarden is meeting the design requirements? <br />a. Remedy - An as-built survey was conducted to verify that the built raingarden meets the <br />Watershed District's requirements. See the attached memo from Earth Evans. <br />Also see the attached memo from the watershed. <br />b. Timeline - COMPLETED <br />8. Plants in the raingarden and along the side of the raingarden have died. <br />a. Remedy - A replacement plant list will be provided, and the dead plants will be replaced. <br />b. Timeline - By October 12, 2007 <br />9. Add a gravel path near the shoreline to clearly define pedestrian walkways through the plantings. <br />a. Remedy - At the direction of the Council, three gravel extensions will be built. <br />b. Timeline - By October 12, 2007 <br />10. The biorolls were installed using two methods. One method has the bioroll pinned to the shoreline <br />at the water level. The second has the bioroll offset from the shoreline. The City has asked which <br />installation method is correct. <br />a. The intended method of construction is to have the biorolls away from the shore, and <br />acting as a wave break. The design also calls for aquatic plants to be planted between <br />the bioroll and the shoreline. Ultimately, it's the roots from the aquatic plants that provide <br />erosion protection. The bioroll is meant to be a temporary measure to protect the plants <br />during establishment. <br />b. Remedy - Bonestroo will provide additional shoreline stabilization in the spring of 2008. <br />Per Gregg Thompson's email, Bonestroo will plant additional shrub and perennial <br />plantings along the shoreline. In addition, Bonestroo will provide a temporary wave break <br />during plant establishment. We are currently evaluating wave break options, and will <br />work with the Watershed District and the City on an acceptable solution. <br />c. Timeline - Spring of 2008. Because the growing season has come to an end, it's best to <br />wait until next spring to install the plants and temporary wave break. <br /> <br />L______ <br />