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I I I I I I I I I I I I I I I I I I I Mr. Ben Urbonas, P.E. Page Three March 20, 1978 Mr. Ben Urbonas, P.E. Page Four March 20, 1978 Finally, when the final design for this project is com- pleted, the engineer should address himsel~ to the sequence of imolementation of the recommended alternatlves so that any increased damage upstream, downstream, or adjacent to the improve- ments as a result of the sequence of implementation of the selected alternatives can be avoided. 3. Reaches D and C. The recommended alternatives in these two reaches appear to be legally sufficient. 4. Reach B. II. Dry Gulch. This portion of the opinion will proceed from the "up- hill" portion of Dry Gulch and comments will be made on all six reaches of the gulch and the alternates discussed and selected in the engineer's report. In regard to the improvements recommended at Wadsworth Boulevard, the same comments made in Paragraph 2 above are applicable. Also, it is not clear from the report what effect, if any, results from no improvements being recommended at Pierce Street. The report states that the twin 36-inch pipes are not adequate and that certainly would appear to be the case if a 102-inch culvert were added upstream of Pierce Street. Before the recommendation of "no action" at Pierce Street is accepted, the engineers should assure the governmental entities that the condi- tions at Pierce Street and downstream of Pierce Street will not be worsened by this recommendation. 1 . Reach F. If considered useful by the governmental entities involved, the engineer should be required to advance some.general suggestions for flood protection improvements between 9uall.and the Agricultural Ditch under different developmental Sltuatlons. Also. the engineers should be requested to add:ess the impact, if any, from the installation of a side channel splll- way on the Agricultural Ditch, since it is not clear f:om.the report what effect this has on the flooding in the reach and lf lt does have an adverse effect some solution to alleviate the increased damage should be proposed. 5. Reach A. As suggested at Page 11-23 of the engineers' report, the effects at Perry Street as a result of the upstream improve- ments should be investigated further to determine if any action should be taken at Perry Street to alleviate the possibility of a structural failure of the street embankment. 2. Reach E. III. North Dry Gulch. The recommended alternative throughout the gulch is a ten-year level of protection in regard to the construction of facilities, but at Page II 18 and 19 of the en~ineers' report: "Larger facilities are advised to reduce floodlng on Colfax Avenue, Wadsworth Boulevard and Kipling Street. . . ." Before implementa- tion of such a recommendation is carried out, the engineers should assure the governmental entities that the larger facilities at these three areas will not increase damage and flooding downstream of the improvements by virtue of the increased flows passing these three areas or violate the criteria set forth in my general comments. These comments are made because it is not clear to me from the report whether the downstream facilities of these three areas will be adequate after the larger facilities are constructed. The recommended alternatives for Reaches Hand G appear to be legally sufficient as stated in the engineers' report. At this time, the engineers are not recommending a con- sidered alternative of a trans-basin diversion of the flows of the North Dry Gulch to Dry Gulch and, therefore, no opinion will be rendered at this time on such an alternative. If such a trans- basin diversion is later considered, a further legal opinion on such a diversion should be sought.