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I I I I I I I I I I I I I I I I I I I 2. The 23rd Street crossing is a low capacity culvert. This presents the problem of relatively frequent road grade overtopping and debris blockage. The trailer court area downstream of the crossing is affected by this condition. Other residential properties in the area are also affected. Some of the floodwaters will be divered from the drainageway at 23rd Street and become tributary to Jackson Street, causing shallow flooding in the area between the channel and Jackson Street (Sheet 10). 9. For the small tributary streams upstream of Highway #6, the number of cross sections used for modelling was limited due to the condition of flooding being at or near critical depth. Where major breaks in the stream bed profile occur and no cross section exists in the hydraulic model, critical depth was estimated from a similar section. The depth was then plotted at the profile break providing a more realistic i nterpo 1 at ion of the flood profi 1 es between sections. 3. At 24th Street, the condition is similar to 23rd Street. A portion of the floodwaters that are forced over 24th'Street will be hydraulically disconnected from the channel with the streets aC1Mng,.as dra i n- ageways. Flows exceeding the street capacities will threaten residentiul properties in this area. Floodwaters from East Fork Kenneys Run also contribute to the shallow flooding area between the two forks. East Fork Kenneys Run: The 6000 foot study reach for East Fork Kenneys Run begins at its confluence with the main stem at 20th Street (Cross section No. 200) and ends 560 feet upstream of the road crossing to the Lookout Mountain School for Boys at Cross section No. 216. Floodplain limits and water surface profiles are shown on Sheets 9, 18 and 19. 4. The High School property has significant damage potential. An exist- ing footbridge limits the capacity of the channel by 50% at one point. Large trees and other channel obstructions limit the capacity of the existing channel. High School buildings adjacent to the channel have doors opening to the creek (Sheets 10 and 20). 5. A shallow flooding area has also been designated for the right over- bank a.rea downstream of the Welch Ditch crossing. Flooding in this area is hydraulically disconnected from the main channel. 6. Existing private road crossing at Cross section No. 133 is subject to frequent overtopping and.probable washout. The residential property upstream of the crossing along Tributary No. 1 is subject to flood damage (Sh~et 11). 7. Highway #6 will experience minor overtopping during a 100-year flood occurrence on Tributary No.1 (Sheet 11). 8. Shallow flooding or sheet flow areas were used to show similar conditions for private road crossings on the tributary streams west of Highway #6. The reach from 20th Street to near the intersection of Ford and Jackson Streets is storm seweredwith Ford Street and the low areas between 20th Street and 22nd Street providing the conveyance area for major flows. Upstream of Jackson Street, an open ditch conveys stormwater between Old Golden Road and the abandoned Interurban Railroad grade. A 24-inch clay pipe outlets flows through the railroad grade. Upstream of the railroad grade and downstream of the Boys School Road, the drainageway intersects with the Welch Ditch, with the drainageway located in a flume over the irrigation di tch. Development along this reach is limited to the area between 20th Street and the Jackson Street - Ford Street intersection. Numerous residential and commercial structures exist along this reach. Upstream of Jackson Street, the majority of the land is State-owned and undeveloped. The following is a description of flooding characteristics and problem areas along East Fork Kenneys Run: 21