HomeMy WebLinkAboutINS-16-013 - Storm Water Management Pond Sediment Removal
REPORT TO: Community and Infrastructure Services Committee
DATE OF MEETING: February 8, 2016
SUBMITTED BY: Hans Gross P.Eng., Director, Engineering Services
519-741-2200 Ext. 7410
PREPARED BY: Nick Gollan C.E.T., Manager, Stormwater Utility
519-741-2200 Ext. 7422
WARD(S) INVOLVED: All
DATE OF REPORT: January 21, 2016
REPORT NO.: INS-16-013
SUBJECT:SWM Pond Sediment Removal
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RECOMMENDATION: For Information.
BACKGROUND:
The city is legislatively obligated to maintain stormwater water quality control
infrastructure such as ponds and hydrodynamic separators under Environmental
Compliance Approvals issued by the Ontario Ministry of Environment and Climate
Change under the Environmental Protection Act and the Ontario Water Resources Act.
In 2015 the city completed bathymetric surveys of each stormwater management
(SWM) pond to determine how much sediment must be removed to restore the full
function of all the ponds. It has been determined 79,000 tonnes of sediment has now
accumulated in SWM ponds. Sediment must be regularly removed from SWM ponds in
order for them to function as designed and approved. The disposal of the sediment
requires specialized handling since it is usually a contaminated material.
On September 14, 2015 council approved tender T15-067 for the disposal of an
estimated 5,000 tonnes of sediment accumulated from pond cleanouts conducted by
operations staff in 2014/2015 at a tendered cost of $336,039. The sediment was stored
and dried at the drying facility located just north of the Battler Yard. Concern was raised
whether “double handling” the material was the most efficient approach to cleaning out
existing SWM ponds. Consequently, staff issued a public request for quotation (Q15-
102) for the removal and disposal of pond sediment to determine if cost efficiencies
could be gained through the competitive process in order to continue meeting legislated
requirements.
*** This information is available in accessible formats upon request. ***
Please call 519-741-2345 or TTY 1-866-969-9994 for assistance.
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REPORT:
METHODOLOGY:
For the purposes of this analysis all HST is excluded from the following figures. Two
methods (industry best practices) were considered in this analysis for cleaning out SWM
ponds:
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METHOD 1External Forces:
Publically tender the work to restore a SWM pond to its original design condition by
removing all sediment and completing any necessary functional repairs to inlet and
outlet structures.
Contractor is responsible for disposing of sediment at a licensed facility or making
suitable arrangements to dry/stabilize material before it is accepted at a licensed
facility.
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METHOD 2City Forces and External Forces:
The SWM utility provides funding for labour, material and equipment costs to
mobilize city forces to restore a SWM pond to its original design condition by
removing all sediment and completing any necessary functional repairs to inlet and
outlet structures.
Sediment is hauled by City Forces andstored at the city’s drying facility just north of
the Battler Yard.
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After sediment is sufficiently dried out the ultimate disposal of the sediment is
publically tendered and a contractor removes the material to a licensed facility.
Note: Consideration was given to having city forces haul and dispose of the dried
material at a licensed facility. The region is no longer accepting pond sediment at
any of their landfills therefore increasing the travel distance to a licensed landfill for
ultimate disposal. Given the required time to dry the material the hauling would be
performed in late summer/early fall. City vehicles are primarily sized to be efficient
for winter control functions and are not an efficient size to haul large volumes of
material for long distances. This task is best achieved using several large tractor
trailer type vehicles to reduce fuel costs and the number of required trips.
ANALYSIS:
In order to fairly compare the actual costs of work previously completed by city forces to
the costs that would be associated with a private contractor completing the same tasks,
a representative SWM pond was chosen and required tasks were collaboratively agreed
upon between operations and SWM utility staff. The SWM utility then prepared contract
documents for the work to be posted for interested parties to bid on and also prepared
an estimate for the works to be completed in the amount of $49,279. There were 6
quotes received ranging from $53,056 to $139,547. The average of the 3 lowest bids
was $60,767. Using this average, a per metric tonne comparison was developed based
on the measured sediment volume in the pond which was 275 tonnes. The result for the
tendered value of removal and disposal of sediment and inlet and outlet repair work if
$220/tonne
completed by a private contractor was .
The next step in the analysis was to look at the actual costs incurred to the SWM utility
by the work completed by city forces on previous ponds that had been cleaned out.
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Over 2014 and 2015 city forces cleaned out and/or repaired inlet and outlet structures at
nine (9) SWM ponds which resulted in an average of 464 tonnes of sediment being
removed from each pond. By consideringlabour, equipment and material (LEM) costs
from the work orders associated with each pond we could determine the total LEM costs
for the completed works were $193,712. In addition to LEM costs, the double handling
and disposal costs also needed to be accounted for. While tender T15-067 was issued
for the removal of 5,000 tonnes of sediment, final weigh tickets revealed that there were
only 4,178 tonnes of material to remove. As such, the final cost for the ultimate disposal
of the sediment at a licensed facility was $172,335. When these costs are combined, a
comparative value for the removal and disposal of sediment in a two-step process and
$88/tonne.
complete inlet and outlet repair work was
DISCUSSION:
There are three primary reasons for the difference in costs. These are:
Allowing the material to dry means tipping fees do not need to be paid for water
weight or a stabilizing agent necessary for saturated sediment to pass the required
slump test to be considered a solid waste under Ontario Regulation 347.
City forces do not need to carry overhead items such as performance, labour and
material bonds or develop project specific health and safety plans.
City forces are not in the business of making a profit.
ALIGNMENT WITH CITY OF KITCHENER STRATEGIC PLAN:
The recommendation of this report supports the achievement of the city’s strategic
vision through the delivery of core service.
FINANCIAL IMPLICATIONS:
Based on this analysis the cost to remove and dispose of pond sediment already
accumulated in SWM ponds can range from $6.9M to $17.4M.
COMMUNITY ENGAGEMENT:
INFORM – This report has been posted to the City’s website with the agenda in
advance of the council / committee meeting.
CONCLUSION:
Based on this analysis, meeting the legislated requirement of removing and disposing of
sediment from small to medium SWM ponds in order to restore their water quality
function is to complete the removal work with city forces and publicly tender the ultimate
disposal of the sediments once they have dried. As such, based on the current
economic climate and the current ability of city forces to complete a part of the work,
Method 2 should be given first consideration for proceeding with this work. When city
forces are unavailable or special equipment is required for medium to large SWM ponds
it may still be necessary to follow Method 1.
ACKNOWLEDGED BY:
Justin Readman, Interim Executive Director of Infrastructure
Services
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