08-24-2016 Additions Packet - Laserfiche WebLink

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Page 1 of 3 To: Honorable Mayor and City Council From: Lee Elfering, City Engineer Date: August 24, 2016 RE: Ryan Industrial Park Road Improvements Proposed Project – Drainage Improvements The earlier memo provided some background and general information relative to the drainage issues being experienced within the Ryan Industrial Park. This follow-up memo summarizes our findings and recommendations of improvements that could be pursued to improve drainage in the area. Drainage Areas The exhibit with the previous memo outlined two swales/ditches that exist along the west edge of the Ryan Industrial Park. The northern most ditch runs from the low area just south of the tracks to the south property line of 3173 Spruce Street. From that point the ditch turns and runs east along the south property line to a private culvert that discharges just behind the curb on Spruce Street. The water then runs south on Spruce Street to existing catch basins. In general, the low area and ditch act as a pseudo pond with a 4-inch outlet. When rains are relatively infrequent and light to moderate in intensity it appears the natural infiltration and storage in the low area south of tracks is sufficient to allow drainage to be conveyed to the low area. As the low area fills with water the flow in the ditch reverses and is conveyed to the 4-inch culvert to Spruce Street. In larger more intense rain events the culvert is overtaxed and additional ponding occurs within the property located at 3173 Spruce Street and storm water enters the floor drains in the building as a secondary outlet. The second ditch begins in the low area along the west edge of Ryan Industrial Park behind 3171 and 3167 Spruce Street. The ditch goes south from this low area to the south property line of 3101 where the ditch turns and goes east along the property line to a public storm culvert under Spruce Street. After going under the roadway the water then enters a second culvert along the north property line of 3066 Spruce Street to Owasso Basin. Both ditches vary in location from totally on the waterworks property to totally on the Ryan Industrial Park properties as you move along their alignment, but do not appear to be within public drainage and utility easements. No plans could be found for either ditch as they were likely created by private property owners to help alleviate the stormwater runoff issues. Based on the survey information, the two ditch systems appear to function independently during small to medium storm events, but there is only a slight grade separation between the two. During large rain events the systems may interact depending on the functionality of the two ditch systems. 13