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4.05.9(2) - A combination of principal (culvert pipe with gated weepholes) and emergency <br />(open channel) spillway systems was provided, as were barriers to control piping along the <br />primary spillway conduit. Item satisfactorily addressed. <br />4.05.9(7) - Requirements for all impoundment embankments <br />(a) Was vegetative /organic material removed from foundation area? Was the foundation <br />base scarified? <br />1. Please provide a statement addressing these requirements. <br />WFC Response: Included with this submittal is a document for inclusion into Appendix 2.05.3(4) -6 <br />that addressed the foundation preparation for Pond NHN -001 including removal of vegetative and <br />organics material, and that the ground was scarified. <br />(b) Was the fill material free of sod, roots, vegetative matter, and frozen soil? <br />2. Please provide a statement addressing this requirement. <br />WFC Response: Included with this submittal is a document for inclusion into Appendix 2.05.3(4) -6 <br />that addresses the embankment fill material of Pond NHN -001 is free of sod, roots, vegetative <br />matter and frozen soil. <br />(c) What layer thickness was used in constructing the embankment? Was 90% <br />compaction deemed sufficient for stability? (The Arcadis design may not have <br />addressed these issues.) <br />3. Please provide statements addressing these requirements. <br />WFC Response: Included with this submittal is a document for inclusion into Appendix 2.05.3(4) -6 <br />addressing that the engineering design for construction of the Pond NHM -001 specified at least <br />90% Modified Proctor Density, ASTM D -1557, routine compaction standard for embankment <br />construction. Actual constructed lifts were calculated to be an average of 10.7 inches in <br />thickness. <br />(d) Is the top elevation 1' higher than the water elevation in the emergency spillway will be, <br />during an event? Will this be the case once any settlement has occurred? <br />4. Please provide a statement addressing this requirement. <br />WFC Response: The SEDCAD runs indicate no flow through the emergency spillway during a <br />25yr -24hr event. The spillway is built with 2 feet from the top of the dam embankment to the <br />bottom of the 10 foot wide emergency spillway. The embankment was compacted to 90% <br />compaction. Assuming worst case scenario of an additional 10% settling, the 2.0 feet spillway <br />depth, minus 10% (0.1 x 2.0 = 1.8) results in an emergency spillway 1.8 feet deep. As stated in <br />response to Item 5 above, even with a blocked primary spillway, and an emergency spillway flow <br />depth of 0.18 ft., the required freeboard of 1.0 feet is achieved. <br />(e) Are the combined upstream and downstream slopes not steeper than 5H: 1 V (they are <br />6H: 1 V), is neither steeper than 2H: 1 V (each is 3H: 1 V). <br />Item satisfactorily addressed. <br />4.05.9(8) - Stability <br />4 <br />