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' <br />1 C �� __.� --► ___a_►1 � ._, 1 1 .� �\_ <br />T'he construction sequence proposed for the improvements assumes that construction will take <br />place in the fall when peak runoff rates aze at a minimum. According to the City, construction of <br />the proposed improvement will not limit their ability to supply water to all of their customers <br />because they have alternative sources capable of temporarily suppl�zng all of the City's water <br />needs. Therefore, the construction sequence should not affect the City's water supply needs. <br />However, a logical construction sequence is presented below: <br />1. <br />2. <br />3. <br />4. <br />Complete improvements to the access road. <br />Install erosion and sediment control measures. <br />Lower water level. <br />Install water control measures. <br />5. Complete clearing and grubbing. <br />6. Begin mining and stockpiling riprap and begin extension of the outlet pipe to <br />accommodate raising the dam embankment. <br />7. Lower the dam embankment and stockpile this impervious material for use later. <br />8. Remove layer of coarse material approximately 5 feet below top of dam and <br />stockpile for use later. <br />9. Complete Spillway excavation and raise dam. Building the dam embankment <br />should be done in layers simultaneously along with placement of the stockpiled <br />impervious material and placement of the riprap on the upstream face of the dam. <br />10. Build concrete grade beam across spillway crest. <br />11. Install footbridge across spillway. <br />12. Clean site and complete seeding and other site restoration items. <br />There are a few other items to be considered regarding construction of the proposed <br />improvements. According to the US army Corps of Engineers, a 404 permit will be <br />required; however, the proposed improvements should be covered under Nationwide Permit <br />No. 3. The construction costs described earlier in the report assumes that a footbridge will be <br />installed for access across the spillway. The City may want to use a larger bridge capable of <br />handling a pickup truck since the controls to the outlet pipe will be located on the opposite <br />side of the spillway. <br />9 <br />