FROM: James D. Herberg, General Manager
Originator: Kathy Millea, Director of Engineering
SUBJECT:
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GREENVILLE TRUNK IMPROVEMENTS, PROJECT NO. 1-24
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GENERAL MANAGER'S RECOMMENDATION
recommendation
RECOMMENDATION:
A. Approve a Professional Design Services Agreement with Brown and Caldwell to provide engineering services for Greenville Trunk Improvements, Project No. 1-24, for an amount not to exceed $4,730,000; and
B. Approve a contingency of $473,000 (10%).
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BACKGROUND
The Greenville Trunk sewer was originally constructed in the city of Santa Ana in 1952. In 1959, a portion of the sewer was reconstructed as a siphon to allow for the Santa Ana Gardens Channel storm drains crossing.
The majority of the Greenville Trunk sewer consists of 24-inch and 27-inch vitrified clay pipe. Nearly all manhole structures on the Greenville Trunk sewer are uncoated concrete manholes.
RELEVANT STANDARDS
* Meet or exceed sanitary sewer overflow regulations
* Comply with California Government Code ?4526: Select the "best qualified firm" and "negotiate fair and equitable fees"
* Protect OC San assets
* Commitment to safety & reducing risk in all operations
PROBLEM
There are multiple issues associated with the Greenville Trunk sewer, including capacity, condition, oversized siphons, and accessibility issues. The Orange County Sanitation District (OC San) Collections Capacity Evaluation Study identified surcharging in the Greenville Trunk sewer under modeled 2040 peak wet weather flow conditions. Closed-circuit television inspection of the sewer indicates that there are cracks, widespread leaking joints, calcification in the sewer, and corroded manholes along the trunk line. Furthermore, the siphons are oversized for the current flow conditions which contributes to accumulation of solids in the siphons. Finally, several manholes along the trunk sewer are difficult for Collections staff to access for maintenance, including one that i...
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