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' 07i20i1990 10:31 FROM 70 P.06 ~ • • to be designed to limit the amount of erosion along the swale, and because of the steepness of the quarry access road, check structures would be required at Frequent intervals to limit the degradation of the swap as it approaches the 54130-inch ewlvert. The amount of sediment available for transport to downstream property would probably not be decreased compared to the existing condition. Option 2: This option is very similar to the Option 1, dr~d does not address the concern of flow diversion. flRing the Cedar Heights Drive street section to convey the runoff originating from the HR-6 basin to the existing Culvert under Cedar Aleights Drive will caus® sediment to be routinely deposited in the street section. ThiB would appear to increase the maint:enanct responaiblity of the Cedar Heights property owners. A8 i.n the case of Option 1, the 54/30-inch culvert would be vvertol:ped +n 10(1-year «:vent <yr in the event the HR-6 culvert becamr. p1uS~ged. option 3: This option does not effectively solve the cvnce~•.a pointed out in the above discussion. In fact, o! the ti•ae options discussed thus far, Option 3 increases the flew and sediment transport (relative to options 1 and 2), to the 54/30- inch culvert and thereby creating the potential for even <lreater damage to the quarry access road and to Slack Canyon Road. Options 4 and 5: These options propose that all of th+a flow originating from basin HR-6 be diverted to the HR-~ basiin and eventually to the 54/30-inch culvert. This option in our c>pinian is unacceptable and creates the potential Pon even +areater lability to the quarry operates. If these options are pursued, the quarry operator would have to make provisio;zs for the handling o1 overflows ontp the publio portion of Black Canyon Road which would involve concurrence from either the County and/or the City of Manitou Springs. Removing the section of 30- inch culvert Prom the 54/30-inch system would increase the capacity sufficiently to prevent overflow on to Black Canyon Road. Design of the roadside swales would have to be completed by the quarry operators. 0~?tlon 6,; ~, ,'his option in our opinion if the moat acceptsble of ';"'the alternates identified thus far. The construction Of a 100- year capacity culvert at the outfall point of the HR-6 bas :cc would prevent the diversion of flows to other basins and thereby relieve the concerns caused by such diversions. This option would also eliminate the Head for hold harmless provisions necessary to implement any of the diversion schemes discussed above. The quarry operator should also be responaik~le !or removing and/or othsrwise•stabilising tho area at the inlet of the HR-6 culvert so as t.o prevent Sediment deposition along the natural ewale and within Cedar Heights Drive. Though a 1,00-year 3