905 80TH ST SW MTORRES AMERICA 2018-09-18

Response: The channel grading has been incorporated into the revised grading plan, in accordance with the previously approved plans. c. The grading in the wet pond and along the pond access road does not match the previously approved grading plan and must be changed unless new design calculations are provided. Response: The wet pond grading and access road grading has been revised to match the previously approved plans. d. The rim elevation of CB 1 is not high enough to provide the required clearance between the top of the restrictor device and the underside of the top slab. Response: The rim elevation of CB 1 has been adjusted to provide 20" of clearance from rim to top of riser. This will allow for the required 6" of freeboard above top of riser. e. An emergency overflow for the pond must be provided in accordance with current City standards. Design calculations will be required. A secondary inflow to the control structure, such as a "jailhouse" opening, must be provided at the design water surface elevation of the pond (e.g., the top of the overflow riser). The design water surface elevation for the overflow spillway shall be a minimum of 6" higher than the stage in the control structure necessary to pass the 100-yr un-detained flow through the riser pipe. The downslope side of the emergency spillway shall be armored to the bottom of the adjacent conveyance channel. Response: A Secondary overflow has been added to the revised plans, and sizing calculations are included in the attached stormwater memorandum. f. The plans show an additional drainage structure, located between existing catch basins 8 and 7, when compared to the previously approved plans. It does not appear as though the information given for the existing drainage system reflects the design information. The design plans appear to show the east-west segment of this system, which parallels 80th Street, to be closer to the right-of-way line than the submitted construction plans. Has the existing system been as-built for this project, or is it possible that the location of the storm drainage system along the southern side of the site is in error? Response: The plans have been updated with storm drainage as-built survey information for the existing structures east of existing CB#5. The remaining existing storm system west of existing CB#5 is in the process of being as-built surveyed and has proved challenging due to heavy brush. The remaining storm information will be obtained as soon as the preliminary clearing has occurred. Based upon the as-built information received to date, the existing storm line is further from the right-of-way line than shown on the design plans and previously submitted construction plans. Once the existing storm as-built information is finalized, PACLAND will ensure that the proposed grading will maintain minimum cover over the pipe and any structures are adjusted to finished grade. g. The pipe entering the pond from the development has a smooth wall interior and a slope of 19.5%. The velocity at the end of this pipe will exceed 25 fps. The proposed energy dissipation at the outlet will not be adequate, even if the outlet is submerged —which it likely won't be during summer months. City standards require an engineered energy dissipater when