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V I 1-7 removed concrete be p I aced on the downs tn,am s I C>f.e of the Turnp I ke and burled. While these Improvements will not allo~' the two existing box culverts to meet the road overtoppIng criteria for a freeway, It Is not considered feasible to add another box culvert. The road Is not over- topped for the 25-year frequency storm runoff. In the vicinity of Wadsworth Boulevar"d, the flood depth in certain areas Is not sufficient to allow for the raised concrete low flow eros Ion controls. Because of the unsuItability for the future roadway designa- tion of Wadsworth Boulevard, we are recommending that the existing 8' x IS' box culvert be replaced with two 9" x 16" box culverts and that the Wadsworth embankment be raised to meet road overtopping criteria. As can also be noted on Sheet 20, there Is a sew'-Ige 11ft station located within the flood plain of Big Dry Creek, Steps should be taken to flood- proof the pump station or to relocate the IJump station outside of the flood plain. The criteria for thIs are not so much matters of economics as the relocation is desirable from the standpoint of public health. The existing culvert through the Colorado and So'uthern Railroad embankment is adequate for more than the iOO-year design frequency. We are recommending that a new 8' x 8' box cLllvert be added to Colorado 121 and that the roadway elevation be raised 111 ordel"' that the road overtopp- Ing criteria Is met. As can be noted downstream of the Colorado and Southern embankment on Sheet 21, the Big Dry Cre'lk flood plain is pretty well contaIned within its banks and does not flo()d existing homes located near the channel on Zephyr DrIve and on 99th Avenue. Between Wadsworth Boulevard and Standley Lake, as sho~m on Sheet 22, there are no other Improvements needed other than to constl'uct concrete low flow erosIon controls. Because the Intended approach to the III g Dr)1 C,.eek des I gn Is non- structural, It Is Intended that dIsturbance of the natural channel be- tween structures at roadways and IrrIgatIon canals be limIted to that necessary to construct the low flow erosion contl"ols. It Is not antici- pated that It will be necessary on a wholesale basis to construct ail of the low flow erosion controls within a short perIod of time. Rather, It is anticipated that unless the channel Is showln9 severe ems Ion problems, the erosion controls will be constructed at the time of development within the vicinity of the needed Improvements. This wll i allow the funding as presented In SectIon IX on a pay-as-you-go basis, with a drainage tap fee assessed against the units developed.