25F - AGMT - DELHI DIVERSION PROJECT

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Preliminary Design Report Addendum No.2 Fine - screen and Broad- crested Weir The maximum velocity through fine screen open area is 5.6 fps assuming a clogging factor of 50 %. The headloss through the fine screen for maximum flow of 100 cfs is estimated to be 0.75 ft. Headloss over the broad - crested weir downstream of the fine screen is estimated to be 0.62 ft. The estimated headloss for dry- weather flow is estimated to be 0.03 ft for the screen and 0.02 ft for the broad - crested weir. Bypass Pipeline from Post fine- screen Chamber to Outlet The proposed bypass discharge pipeline from the proposed post fine - screen chamber to the outlet structure is shown in Appendix A -1 sheet PD -1. It consists of one 48 -inch diameter RCP approximately 50 feet long following and a slide gate structure at the intake within the Delhi Channel. The estimated flow velocity for maximum flow of 100 cfs is estimated to be 8 fps, and head loss is estimated to be 1.7 feet. The estimated velocity and headloss for dry- weather flow of 0.4 cfs are negligible. $.8 RELIABILITY While all municipal wastewater treatment facility Classes I, R and III will require the facility to have redundancy /reliability to maintain the design capacity with one large unit out of service (Design criteria for mechanical, electric, and fluid system and component reliability for wastewater treatment facilities, Bulletin 430 -99 -74 -001), such redundancy is not required for stormwater storage /sedimentation facilities (Storage /Sedimentation Facilities for Control of Storm and Combined Sewer Overflows Design Manual, Bulletin EPA/600 /R- 98/006, Storm Water Technology Fact Sheet Flow Diversion, Bulletin 832 -F -99- 014). A maintenance program should be established to ensure that the system functions properly. The diversion facility should be inspected to remove debris prior to the rainy season and shortly after a significant rainfall event. This project will have two intake structures, with only one in service at a time. This will aid in redundancy /reliability. The proposed Diversion Facility plan layout and sections are shown in Appendix A -1 sheet PDA URS 14 25F -146