APPCOR10484 - Laserfiche WebLink

Home Browse Search

Carol Russell & Ed Bischoff -2- April 28, 1982 4) Is the diversion properly designed? The applicant has previously submitted a map showing the location of the diversion (Hydrology flap, sheet 2), a longitudinal profile and plan vic~/ of the diversion (Hydrology Map, sheet 4), and modified channel cross-sections for the 100-year design flood as calculated by GEC SOAP contractor (submitted Pfarch 22, 1982). This information should be asseysbled into a detail plan, and certified by a qualified registered professional engineer as required under Rule 2.05.3(4). The plan should describe the transition from the natural drainage to the diversion channel. This point should be clearly identified on the plan view and channel profile (sheet 4). The applicant should show how flows are diverted from the natural channel into the diversion. Provide design details for any structures used. For each segment of diversion channel, the applicant should provide the flow velocity, identify the material into which the channel is excavated, and identify when channel protection would be required. The applicant should show on the plan view and in profile (sheet 4) all areas where riprap is used. The applicant should provide discussion and calculations showing riprap sizing, gradation of the riprap, nature of the filter blanket used, method of emplacement, and the method used to determine durability. An unnamed tributary enters the permanent diversion at station t9 on the profile. The applicant should show all modifications to the tributary and the diversion to accommoriate this confluence. (The tributary is much steeper than the diversion channel. Would the break in slope cause a fan to form at the mouth of the tributary?) The culvert under County Road 92 is undersized. It is uncertain who is respon- sible for the culvert. If the culvert is installed in an undisturbed portion of the stream, it is the county's responsibility and we would have no jurisdiction. If, however, the culvert was installed when the channel was realigned for the Magpie Creek diversion, Dorchester should install a culvert sufficient to pass the 100-year event. In order for the Division to determine whether the Magpie Creek diversion should be approved as a permanent diversion, the above information should be submitted to the Division. In either case (permanent or temporary), a certified plan must be provided by the operator. In this case, "as built" drawings showing whatever modifications are necessary to meet the current performance standards would be acceptable. Let me know if you have any further questions. /mt cc: Dave Shelton Jim Pendleton