14 ATTACHMENT 1-5 - Laserfiche WebLink

PUD-138 and VTM 8616 Planning Commission Page 13 of 30 reduce the number of manholes to the extent feasible. (Address this condition prior to improvement plan approval) (PROJECT SPECIFIC CONDITION) 46. GRADING/CONFORM ISSUES: Referring to the Vesting Tentative Map, the following grading issues shall be reconsidered in the design (Address this condition prior to improvement plan approval): a. Referring to the Geotechnical Feasibility Report, Figures 2 and 8 show cross-section A-A through a landslide with recommended corrective grading. This area does not appear to be enclosed within the dashed line on the Vesting Tentative Map with note reading, “Approximate limits of landslide repair-remove & replace slide deposit, restore to original grade”. This landslide shall be repaired as recommended in the report. b. Section B on Sheet TM 6.0 of the Vesting Tentative Map shall be modified for the grading conform at neighboring properties to the north. In lieu of grading down from the pad to the existing ground surface at the subdivision boundary, instead the section must show retaining walls such that no storm runoff will flow across the subdivision boundary. (PROJECT SPECIFIC CONDITION) 47. MUNICIPAL REGIONAL PERMIT (C.3): Referring to the Vesting Tentative Map together with the Bay Area Hydraulic Model (BAHM) report, the following design parameters shall be checked by the applicant (Address this condition prior to improvement plan approval): a. The note at the bottom of the table on Sheet TM 5.0 states, “The calculations are based on the Alameda Countywide Clean Water Program C.3 Technical Guidance…”, yet a report was submitted using BAHM. The note should therefore read, “The calculations are based on the Bay Area Hydraulic Model (BAHM). When comparing the numbers in the table to the BAHM calculation, the following discrepancies were noted: i. The input parameters in the BAHM calculations for DMA 2 (page 5) indicate an impervious total of 6.238 acres whereas the summation of areas from the table suggest a total of 6.45 acres (81,700 SF + 104,400 SF + 95,000 SF = 281,100 SF = 6.45 acres). ii. Based on the impervious area total, the BAHM calculations (page 12) indicate a needed area for DMA 2 of 25,000 SF (200’ X 125’ = 25,000 SF). In contrast, the table shows a provided area of 24,850 SF. b. Because the storm drain design proposes the use of two parallel pipe networks, one for storm runoff requiring treatment, and one for storm runoff from open space areas that does not require treatment that converge at BMP 2, BMP 2 will function both as a treatment feature and detention basin during large storm events. The BAHM calculations (page