City Council
259 N. Wilma Avenue
Ripon, CA 95366
MEMO
To: Honorable City Council
From: Christiana Giedd, Associate Civil Engineer
Date: 03/14/2023
Subject: Fleet Maintenance Facility Change Order #1
RECOMMENDED ACTION:
Approve Change Order No. 1 in the not to exceed amount of $288,622 for raising the elevation of the existing berm at the Wastewater Treatment Plant disposal ponds in order to provide additional storage capacity (funding source: Sewer Capital Enterprise Fund).
BACKGROUND:
The Fleet Maintenance Facility Project was awarded to Diede Construction, Inc. at the December 13, 2022 City Council meeting for an amount of $11,156,000. The Fleet Maintenance Facility Project will involve the construction of a 12,500 square foot maintenance building and parking lot.
DISCUSSION:
The City’s Wastewater Treatment Plant (WWTP) disposal ponds had capacity issues during the significant recent rain events. The City’s consultant reviewed available data and found the following:
1. The groundwater elevation is above the bottom of the ponds as a result of the hydraulic connection with the river. This increases the volume of water in the ponds and reduces percolation rates.
2. On average, the rainwater has doubled the volume of water typically discharged into the ponds from the WWTP. This water needs to be disposed of through percolation.
3. At this point, there is little that can be done to increase percolation rates. The focus is to increase the storage capacity and not overflow into an unpermitted area.
The Fleet Maintenance Facility Project involves the removal of over 7,000 cubic yards of dirt from the site. The dirt was planned to be hauled away by the Contractor. Staff has requested the contractor provide a change order to utilize the excess dirt from the Fleet Maintenance Facility project and complete the improvements to the berm surrounding the disposal ponds to increase the storage capacity, as summarized below:
Remove any rock or asphalt on the surface of the existing berm Scarify the surface and prepare it for adding layers of dirt Add layers of dirt and compact to 90 percent relative compaction Replace the sections with a rock base or asphalt
Once these improvements are complete, the storage capacity of the disposal ponds will be increased to help prevent an overflow during significant rain events.
FISCAL IMPACT:
The attached Change Order No. 1 is in the amount of $288,622 and will be funded through the Sewer Capital Enterprise Fund. The amended construction contract price is shown in Table 1.
Table 1 – Current Contract Price
Amount
Original Contract Price $ 11,156,000
Change Order 1 $ 288,622
Current Contract Price $ 11,444,622
Attachments:
1. CO 1