Laserfiche WebLink
Mr. Don Deere, P.E. Page 2 of 3 <br />Acceptance of the Design and Construction Documents for the Proposed Stonewall Springs Central Dam <br />March 14, 2008 <br />• Rule 5.9.4.3.3 — Upstream Slope Protection <br />The proposed Stonewall Springs Central Dam incorporates conventional riprap and riprap <br />bedding for the upper 10 vertical feet of the main dam embankment where the slopes are 3:1 <br />(horizontal :vertical). The lower embankment slopes have been flattened to 5:1 (horizontal:vertical) <br />and the embankment material will consist of a clayey material. The following reasons are <br />presented to justify the request to waive the requirement for conventional riprap slope protection <br />on the lower portion of the embankment: <br />a. The flatter slope will reduce wave energy. <br />b. The embankment will be constructed out of a clayey material that is relatively resistant to <br />erosion. <br />This office accepts the above waiver request with the understanding that the owner will <br />maintain the embankment and promptly repair any erosion. <br />• Rule 4.2.3.3.2 and Rule 5.9.6.1.3 — Pipe emergency spillways are not considered acceptable <br />emergency spillways. <br />The proposed Stonewall Springs Central Dam has a design for a 10 -foot wide reinforced <br />concrete box service and emergency spillway. <br />The following reason is presented to justify the request to waive the use of a pipe spillway <br />as an emergency spillway: <br />a. The dam is an off - stream storage ring dike, which is not subject to excessive amounts of <br />debris. <br />Based on the above reasoning, this office accepts the above waiver request. <br />• Rule 15.3.2 — Monument Survey <br />Due to the excessive cost and difficulty in repeating the survey with accuracy, the design <br />engineer proposes a second order surveying for ail movement monuments in lieu of a first order <br />survey. This office accepts the above waiver request. <br />• Rule 5.10.1.4 — Dam owner possessing the title to the property or permanent easement for a <br />minimum distance of 50 feet or the height of the darn <br />proposed west embankment is adjacent to Nyberg Road and is within 15 feet of the <br />road right -of -way and 30 feet from the edge of the road. Due to the flat and regular nature of the <br />terrain it is the engineers opinion that there is adequate access for maintenance and inspection of <br />the west embankment. This office accepts the above waiver request. <br />• Rule 5.10.1.2 — Borrow areas shall be located at least 200 feet from either toe of the dam. <br />The majority of the storage in the reservoir will be created through excavation and mining <br />of the materials. The engineer has performed a post excavation stability analyses for both the <br />