2016-09-02_HYDROLOGY - M1992069 - Laserfiche WebLink

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Mr. Roger Schmidt September 2, 2016 Page 3 o June 22, 2015 site visit by Ben Urbonas, P.E. (outside reviewer to WWE) and Ian Paton, P.E. Mr. Urbonas subsequently provided input and peer review for the development of this letter. o July 25,2016 site visit by Ian Paton, P.E. Note: see Appendix A for photographs from the site visits. • Infonnation collected during discussions with Christie Coleman, P.E., Water Resources Engineer for the City of Greeley, who accompanied WWE personnel on all of the site visits. • An initial engineering assessment of hydrology and hydraulics for the site. A list of documents reviewed is provided in the References section at the end of this letter report. This report was prepared based on the information WWE received and reviewed as of August 8, 2016. If additional information is provided to WWE,we may need to update our findings. CHRONOLOGY OF EVENTS A chronology of conditions and events at the Boyd-Freeman Ditch, Al Pit, Iverson/Martin Marietta Pit and the immediate vicinity was developed based on discussions with Christie Coleman, P.E., documents provided by the City of Greeley or otherwise obtained by WWE, and a review of aerial images dated from October 3, 1999 to June 19, 2014 (see Appendix B for aerial images. Close-up aerial images for different dates are on Figures B.1 through B.11. Aerial images of a larger area are shown on Figures B.12 through B.22). The chronology of conditions and events is provided in Table 1: Table 1. Chronology of Conditions and Events at the Boyd-Freeman Ditch and Al Pit Year/ Description of Conditions / Events Time Frame Prior to The Al gravel pit location was formerly grazed prairie land use. development of (See Appendix B, Figure B.12,which shows the conditions that Aggregate existed at the location of the Al gravel pit in October 1999, prior to Industries (AI) the Al gravel pit being constructed). gravel pit in 1999 to 2001. • When built, the Al gravel pit was in unincorporated Weld County. • A Special Review Permit was issued for the gravel pit by Weld County on October 21, 1992. The permit required grading to provide stabilized shoreline around the lakes and grading to control erosion. (Note that the Al gravel pit is now located within the Greeley City limits).