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CC - Approval of the Final Plans and Specifications and Authorization to Publish a Notice Inviting Bids for the Transfer Station Rain Garden Project, Phase II, PZ-948.
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Meeting Date: September 11, 2017
Contact Person/Dept: Lee Torres/PW
Phone Number: (310)253-6457
Fiscal Impact: Yes [X] No [] General Fund: Yes [X] No []
Public Hearing: [] Action Item: [X] Attachments: []
Commission Action Required: Yes [] No [] Date:
Public Notification: (E-Mail) Meetings and Agendas - City Council (09/07/17);
Department Approval: Charles D. Herbertson, Public Works Director/City Engineer (08/25/17)
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RECOMMENDATION
Staff recommends the City Council approve the plans and specifications and authorize publication of a Notice Inviting Bids for the Transfer Station Rain Garden Project, PZ948, Phase I.
BACKGROUND
The Public Works Environmental Programs & Operations Transfer Station Facility (Facility) functions as a transfer facility for recyclables, municipal solid waste, and organics waste collected locally from residential, commercial, and industrial properties within Culver City and portions of the City of Los Angeles. The refuse and recyclables are transported from the Facility to landfills and recycling facilities and the organic material is sent to a composting facility.
The Facility’s site is nearly 100% impervious. Approximately 80% of the site is graded toward two trench drains with filtration devices that discharge directly into Ballona Creek. The remaining 20% of the site drains towards the front property into previously constructed rain gardens along the parkway on the north side of Jefferson Boulevard.
Due to the Facility’s function and daily operations, pollutants such as trash, oil & grease, bacteria, iron, copper, lead, and zinc may be found on site. The existing trench drain filtration devices are high maintenance and are easily saturated, leading to a limited effective life cycle. Furthermore, half of the Facility’s roof drainage currently discharges directly towards Jefferson Blvd, un-treated.
Therefore, in order to maintain compliance with the State’s Industrial General Permit (IGP) and the City’s NPDES MS4 Permit, the City is in need of more viable structural Best Management Practices (BMPs) that can treat/retain the first 1.1-inch rainfall (equivalent to the 85th percentile, 24-hour rain event) of all potential pollutants from the site, and to promote the City’s storm water pollution prevention program.
Staff proposed a two-phased stormwater project to meet compliance, Stormwater Diversion Project, Phase I and Rain Garden Project, Phase II.
Stormwater Diversion Project, Phase I
On May 30, 2017, City Council approved the construction award to Metro Builders and Engineers Group for the Stormwater Diversion Project, Phase 1.
This project proposes to construct a storage system consisting of two (2) underground storage tanks that would collect and store the first 1.1 inch of rain fall from 80% of the Transfer Station site. The storm water and urban runoff will be diverted from the existing trench drains into underground storage tanks with a combined storage capacity of 31,000 gallons. After the storm has passed, the tanks will be pumped into the sanitary sewer system for treatment at the Hyperion Treatment Plan.
The construction of the Stormwater Diversion Project is currently underway and scheduled to be completed by the end of November, 2017.
DISCUSSION
Rain Garden Project, Phase II
Currently, the southern half of the Facility’s roof run-off discharges directly to Jefferson Boulevard untreated. This project includes the construction of rain gardens with above ground bio-filtration systems along the property’s frontage to divert and capture run-off from approximately 7,000 sq. ft. of roof area. The proposed rain garden will have a design volume to accept, filter and infiltrate runoff from the Facility’s roof. Furthermore, cisterns with a total capacity of approximately 1,400 gallons will be installed for harvesting additional runoff to be used to supply the proposed drip irrigation system.
The tentative project schedule is as follows;
Rain Garden Project, Phase II
• Construction Bid - September, 2017
• Construction Award - November, 2017
• Complete Construction - February, 2018
FISCAL ANALYSIS
The project is funded by Urban Run-Off Mitigation and Proposition 1 Grant Funds.
|
Estimated Project Expenses |
|
Construction - Rain Garden Project, Phase II |
$175,000 |
|
Const. Management/Inspection Services/Design Construction Support |
$25,000 |
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Geotechnical Material Testing |
$10,000 |
|
Total Estimated Project Expenses |
$210,000 |
|
Available Funds |
|
Urban Runoff Mitigation Fund, 434, PZ948 |
$212,698 |
|
Baldwin Hills Conservancy Prop 1 Grant Fund |
$56,000 |
|
Available Funds |
$268,698 |
ATTACHMENTS
None
MOTION
That the City Council:
1. Approve the plans and specifications for Transfer Station Rain Garden Project, PZ948, Phase II; and
2. Authorize the publication of a notice inviting bids for the Transfer Station Rain Garden Project, PZ948, Phase II.