HomeMy WebLinkAboutStaff Report 382-08City of Palo Alto
City Manager’s Report
TO:
FROM:
DATE:
REPORT TYPE:
SUBJECT:
HONORABLE CITY COUNCIL
CITY MANAGER
OCTOBER 6, 2008
INFORMATIONAL
Fourth Annual Update Of The Palo Alto Landfill Capacity
DEPARTMENT: PUBLIC WORKS
CMR:382:08
This is an informational report and no Council action is required.
BACKGROUND
In the response to the City Auditor’s~review of the Environmental Service Center (ESC) proposal
(CMR:ll4:05), staff agreed to provide City Council with annual reports on actual tonnages,
remaining landfill capacity and general landfill closure updates as they developed. This is the
fourth annual report.
DISCUSSION
In order to determine the remaining landfill volume, a photogrammetric survey is performed
each year in May. Photogrammetry is the science of taking measurements from photographs.
The photogrammetric survey involves an aerial photograph of the landfill to help measure the
remaining volume of air space. The latest aerial photo was taken on May 15, 2008. The City’s
landfill consultant completed a volume calculation in September 2008 and estimated that as of
May 15, 2008, there is a total volume of 427,000 cubic yards (cy) remaining in the landfill. This
figure is calculated by subtracting the landfill’s existing topography elevations from the
elevations of the approved final grading plan, approved by the California Integrated Waste
Management Board, Regional Water Quality Control Board, and the Santa Clara County Local
Enforcement Agency. It should be noted that a revision to this final grading plan was approved
by the Byxbee Park designer (Hargreaves Associates) in April 2008. The refuse fill volume
difference between the approved and revised plans in the remaining fill area is approximately 2%
and should have a minimal impact to the remaining time until closure. Staff projects that
173,000 cy of that remaining volume (in the remaining fill area) will be depleted by landfill final
cover soil, leaving 254,000 cy of net landfill volume for filling refuse, asphalt-concrete waste,
and cover soil. During the last five years, the volume calculations indicated volume depletions
of 129,625 cy; 111,828 cy, 109,002 cy, 88,640 cy and 85,188 cy, (respectively). To determine
.the estimated landfill closure date, the average volume depletion over the last three years is
calculated (104,857 cy) and projected into the future. Last year the projection indicated the
landfill would reach capacity sometime in late 2010. This year, the projection indicates the
landfill will reach capacity (the net volume will be depleted) sometime late in 2010, about the
same time projected as last year.
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It is important to note that the landfill site life estimate is based on assumptions and current
conditions. Some of those assumptions and conditions utilized for this site life estimate are:
continued receipt of average amounts of incoming refuse, cover soi!, and asphalt concrete waste,
weight to volume density conversion ratios, estimates of on-site soil stockpiles, estimates of final
cover soil volumes, plus an annual one percent tonnage increase due to population increase and
economic activity. Also, it is possible that when additional zero waste operational plan programs
are implemented, less volume will be consumed per year, thus extending the site life estimate
slightly. A change in any of these assumptions or conditions would likely produce a change in
the landfill site life.
Staff will continue to provide Council with closure information on an annual basis and will
return to Council sooner should conditions change.
PREPARED BY:
DEPARTMENT HEAD:
RON ARP /
Manager, Environmental Control Programs
GLENN S. ROBERTS
Director of Public Works
CITY MANAGER APPROVAL:
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