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is uncle.u� �vhat ���ill happcn to drainage in the interim. In addition, the new facil;[ies must <br />be constructed as early in the pioccss as possible to provide mitigation For the projcct. <br />1'he presence of the new 36-inch LCPG on the TGSC plan is confusing (sheets G2.0 and <br />G2.1). <br />On shcet G2.0, notcs arc gi��cn for cxisting cbs 9-15. I cannot tind cbs 13 and 15 <br />Sheet 9.0 <br />Il is unclear �i�hat �vill happen to the apen ends of thc existing pipes that will be filled <br />when the pond bottoms are raised. <br />The location of tlie water main must be shown in cross section GC. <br />Unless the west poi�d is lined, the dcsign of this pond will resiilt in an incmase of almost <br />9 fcet of s!anding hydraulic head on ,he upstream side. This will creute a hJ�draulic <br />gradient across tlie dam that doesn't currently exist e�cept in large storms. The effects of <br />this change must be analyzed by a geotechnical engineer and mitigated iC necessar}� to <br />protectthe structuralintegrity ofthe dam. <br />On cross section G-G, it looks like the upper 24" SD is conncctcd to the catch basin on thc <br />west sidc of die trail. Ho�vever, on the plan view, this docsn't appear to be the case. This <br />item should be clarificd. <br />The cxisting 2a-inch pipe that is connecting the two ponds will be submcrged, proUabl�• <br />lias open joi�its, and serves no apparent function. It should bc plueged and abandoneti. <br />Cross section G-G sho�vs only 1 foot of live storage in the pond. <br />'1'he call-out for the 5' bench on cross section G-G looks like a wall... <br />Che design of tlic ponds �vill result in a siwation where thc saturated cicvation oCthc <br />henn/trail behveen the two ponds will try and reach an elevation of 479. There is a year <br />1969 manhole and se�ver main to the south that may be impacted, in terms of incrcascd <br />infiltration, by die increase in ground water elevatian. <br />I he �ollowin� addition�l notes shall be provided on the drainaec nlans: <br />l he ponds must pass a leak test before the project will receive final approval. Ponds sl�all <br />bc fillcd witl� water to the elevation of the outlets, and inllow prevented for 24-hours. �I�o <br />pass the Ic�k test, thc watcr cicvation may not dron more than 2-inches in the 24-hour <br />�icriod. Pond soils should hc saturatcd beforc hecinning the 34-hour tcst period. <br />� <br />s �jrimmcrin\�cord'�pr_ cvcrc�t mull �'J <br />