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<br />& Cl!J' 0/ Littleton <br /> <br />If'~ <br />~~ <br /> <br /> <br />Photo 1 . Looking downstream of Carr Street after <br />the August 1999 flash flood (UDFCD), <br /> <br /> <br />Photo 2 - East side of Carr Street, August 1999 <br />(UDFCD), <br /> <br />Flash flooding also occurred on Massey Draw on June 27, 2004. Rainfall depths of 2.96 inches west <br />of the hogback and 2.05 inches just northeast of Ken Caryl Avenue and C-470 were observed and/or <br />estimated. An average rainfall depth for the entire basin was not available. West Ken Caryl Avenue <br />under C-470 was reported to be flooded 2- to 3-feet deep. On the Deer Creek Golf Course, the flood <br />flow split west of the West Rockland Drive cul-de-sac bulb, with water flowing both north and south of <br />the West Rockland Drive. It was estimated that approximately 7S percent of the water flowed north <br />into the area between West Coco Place and West Rockland Drive. The culverts under South Oak <br />Street were overtopped and the water flowed east into the detention pond (Pond #2). The detention <br />pond did not have an emergency overflow capable of handling the excessive flow from Massey Draw. <br />Inadvertent detention of stormwater was observed west of South Oak Street. <br /> <br />Several homes along the north side of West Rockland Drive were flooded to a depth of approximately <br />three feet due to restricted culverts under South Oak Street and West Rockland Drive (photos 3 and <br />4). It is thought that a portion of the fences along West Rockland Drive east of South Oak Street <br />contributed to the structure flooding after becoming plugged with debris. The Garrison Street culvert <br />was severely eroded, and extensive stream bank erosion occurred (Photos 5 through 8). By <br />comparing the field evidence to the hydraulic model results from this study, the flows were preliminarily <br />estimated to approximate the 1 O.year storm event Massey Draw at the northwest end of the golf <br />course was estimated to be flowing at approximately 1000 cfs and the flow in the Meadow Ranch area <br />was estimated to be in the range of 1200.1500 cfs. Information regarding other flood events in the <br />study watershed is not available. <br /> <br />2.7 Wetland and Riparian Zones, Flora, Fauna and Threatened or Endangered Species <br /> <br />ERG Resources was retained to map potential wetlands and other waters of the U.S. and to identify <br />potential habitat for Preble's meadow jumping mouse (Zapus hudsonius preblel), Ute ladies'.tresses <br />orchid (Spiranthes diJuvialis), and Colorado butterfly plant (Gaura neomexicana ssp. coloradensis) <br />along Massey Draw and SJCD South tributaries. These studies were conducted on a reconnaissance <br />level and jurisdictional wetland delineations were not conducted during this site review. This report, <br />prepared for planning purposes only, provides information on existing site conditions and resources, as <br /> <br />0\ <br /> <br />Ma~sey Draw <,II(] SJCD fScutn) rvlc?<p Dratrogew<ry Planning Upd<lre <br />Concepr~1 Design Report <br />Feoruaty 2006 <br /> <br />well as current regulatory guidelines related to those resources. ERO's Wetland Mapping and <br />Threatened and Endangered Species Habitat Assessment is included as Appendix F. <br /> <br />2-2 <br />