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1 <br /> <br /> <br />I lying Westerly of the Snyder Quarry Access Road was redefined as Subbs.sin 1- <br /> I.c. and was indicated to outfal! into the 54"/30" Guard House Facility. <br />, However, no accommodation was made to divert the flow Prom ei[her they HR-6 <br /> culvert location to the Guard House facility or to the new culvert location. <br />' The MLRD leas directed Castle Concrete Company to install a Facility Por a <br />Q~ storm event at the HR-6 location. it is the Consultant's opinion that <br /> this cannot be done without creating a potential problem at the existing <br /> facility in Cedar Heights Drive or on the road itself. In order to eliminate <br />' any potential storm damage downstream of the proposed HR-6 culvert, a <br /> sui[ably sized culvert would be required across Cedar Heights Drive :at the <br />~ originally master-planned "Proposed Culvert A" location. This would require a <br />' 36" CSP culvert (HW/D=1.5) with a headwall entrance condition be installed at <br /> both HR-6 under the the access road and "Proposed Culvert A" at Cedar <br /> Heights Drive. <br />1 <br />The MLRD has agreed to consider optional solutions provided thE~y are <br />mutually agreed to by both Castle Concrete Company and the Cedar Heights <br />representatives. !n order to evaluate potential options, a detailed analysis of <br />the existing facilities and proposed flows within this I-1 subbasin ha: been <br />done. Following is a summary of that analysis. <br />' CURRENT CONDITIONS <br />.( <br />,~ <br />~ ° ~•' <br />~ ~~ <br />~' <br /><< <br />~~. <br />t 1. EXISTING FACILITY IN CEDAR HEIGHTS DRIVE ~ c,~ ` ~ ~' <br />The existing facility in Cedar Heights Drive consists oP a 24" CMP <br />with a concrete lined entrance "bowl". The pipe capacity, based on <br />available headwater depth (HW/D=2.3 actual), is 25 CFS. The pipe capacity <br />based on a straight grade Prom entrance to exit (9.9%) is 38.5 CE'S. !t <br />does not appear that the entrance condition could be modified to <br />significantly increase the capacity beyond the 25 CFS. <br />The facility is located approximately 400 feet Southerly of the <br />' Proposed Culvert Aroadway/natural drainage course intersection. Flows <br />Prom the natural drainage course (Subbasln HR-6) currently enter Cedar <br />Heights Drive and are carried in a concrete curb and guttered street <br />' section to the existing facility. The street capacity in this section of <br />Cedar Heights Drive is approximately 19.4 CFS per side or 38.8 CFS total <br />(based on an existing minimum grade of 3.2%, a mat width of 30 feet, and <br />a crown of 2%). Maximum allowable flow in Hillside Residential Sweets <br />t per current Clty criteria is 25 CFS total. Cedar Heights Drive is a private <br />road. <br />The naturally occurring contributing basin to the Cedar Heights Drive <br />culvert is as follows: <br /> <br />1 <br />2 <br />.~ ~ GS <br />~~~ <br /> <br />