1. “ Gerrard Street Watermain”
Oscar A Orellana / September 22, 2016,
11:45 AM @ Metro Hall Room 303
2. Agenda (proposed)
• Background / Project Description – Rationale / Problem description
• The project Class Environmental Assessment (EA)
• Pre-design, Detail Design and Services During Construction
• Gerrard St Watermain Construction
• Issues / Opportunities / innovations (what went wrong / what went right?)
• Accomplishments / Lessons learned (what did we learn / change?)
• Next Steps (how is this changing the way we do things?). Conclusion.
• Questions (post a couple of FAQs and have answers ready in case there aren’t a
lot of takers at the beginning of Q& A session)
3. Background
• The Gerrard St Watermain was initiated by Toronto Water’s, Water Supply Unit, as
part of the Cast Iron Watermain Replacement Program. As a result of the Joint
Optimization Study (JOS), a City of Toronto – York Region Study, Toronto Water
identified major watermains that needed to be replaced to increase capacity and
maintain the safety and reliability of the watermain network.
• The existing watermain to be replaced was a 900mm cast iron watermain that run
from Spadina Avenue to Sumach Street, along D’Arcy St, Mc Caul St, Elm St,
Elizabeth St, Gerrard St, ending at Sumach St.
4. The project Class Environmental Assessment (EA).
• The project EA, Pre-design, Design and Construction was managed by the
Engineering & Construction Services (formerly Technical Services Division)
• The Class Environmental Assessment was started with an REOI in February 2005,
through which four consultants were short-listed: McViro, R. V. Anderson, Earth
Tech and Chisholm Flemings & Associates.
• An RFP was issued in 2005 to the above noted consultants and the Class EA
project was awarded to Chisholm, Flemings & Associates in January 2006. The
Class EA Study was completed in January 2008.
• A preferred route was identified along the same route as the existing 900mm
watermain. The new watermain diameter was upsized to 1650mm, as a result of
JOS and Toronto Water Hydraulic Modelling.
7. Pre-design, Detail Design and Services During Construction
• In April 2008, an RFP was issued for Pre-design, Detail Design and Services
During Construction. The project was awarded to Trow Associates Inc. (now exp
Services Inc.) in August 2008.
• The project design was carried out by Trow Associates from November 2008 to
November 2010.
• The design produced a 1650mm diameter steel watermain, 14mm in thickness, 3.9
kms in length, internally cement mortar lined, to be constructed all in tunnel 25
metres below the surface, with a total of 6 large shafts (6m x 12m in size, 25m in
depth) for launching and retrieval of the Tunnel Boring Machine (TBM). The design
also proposed a 2.5 m diameter tunnel with 10mm thick steel liner plates, which
was later changed by the contractor C & M McNally to steel rib and lagging primary
liner.
10. Gerrard Watermain Construction
• The Construction Contract was tendered in December 2010 and awarded to C & M
McNally by the Public Works and Infrastructure Committee in September 2011.
• The award was delayed to late 2011 (due to insufficient funding that year), so we
could start construction in 2012. The value of the contract was $80,276,112.00
excluding HST
• An Order to Commence Work was issued in December 2011 and construction
actually started in January 2012.
• The contract duration was set in the contractor’s bid at 175 weeks or roughly 3.5
years. The contract completion date was determined as June 2015.
• The watermain construction was completed on time and under budget. Six months
were added for extra work to fill the abandoned 900mm watermain with cellular
grout, which was not part of the original contract. The new 1650mm watermain was
fully commissioned in December 2015.
15. Issues / Opportunities / innovations (what went wrong / what
went right?) 2 slides
• Issues – In 2011, a new City Council was elected. We had obtained a permit to use the Allan
Gardens Park from the previous City Councillor. The new Councillor initially opposed the plan and
ask to find an alternate location. It took a month to resolve this issue with assistance from the senior
management.
• Opportunities – Upon request from the Councillor, the shaft hoarding at Allen Gardens were painted
by the first nations artists and these murals were one of the longest piece of such art in Canada .
• Innovations –In the Tender, Schedule of Price Savings, the contractor proposed a change of the
tunnel liner from 10mm steel to galvanized steel rib and lagging and offered the City $6,200,000 in
savings, which was accepted by the City.
• Upon award, the contractor offered a further change from galvanized steel rib and lagging to black
steel rib and lagging which was accepted and resulted in further savings of $1,387,214
• A change in method of joining the steel pipes, from butt welded joints to lap (bell and spigot) welded
joints, resulted in further savings of $952,000.
• What went wrong – The contractor applied cement mortar lining in their shop, contravening the
contract specifications that called for in-situ cement mortar lining. Bracing of the pipes was required
for Transportation back to the job site to minimize damage to the lining. Defective lining had to be
repaired on site. The contractor assumed the cost of the above.
17. Accomplishments / Lessons learned (what did we learn /
change?) 2 slides
• Accomplishments - Overall, the contract completed on time and under budget. Upon
completion $6 million in contingency and provisional amounts were not spent. A Certificate
of Substantial Completion was issued on November 17, 2015. There was a contract
extension from June to December-2015, as filling the abandoned 900mm watermain with
grout was added to the scope.
• Lessons learned – Maintaining good communications and professional relation with the
contractor, consultant, and the operating division staff was the key to success. Fairness
and good faith can help achieve strong bonding among all parties involved.
• The contractor offered to change the 20MPa sand-cement grout, in the tunnel annular
space, to 0.5 MPa cellular grout, including a $1 Million dollars credit, which was rejected
despite consultant’s recommendation, on the basis that the change would drastically
reduce the external load bearing capacity of the watermain cross-section. It took strength
to say “NO” to the contractor and the consultant. But, we cannot introduce risk for long
term as a result of cost savings. All cost savings offered by the contractor have to be
analyzed for the 100+ year of life of the infrastructure.
18. Next Steps (how is this changing the way we do things?)
Conclusion
• Trunk Watermain construction, all in tunnel, drastically minimizes excavations and
traffic disruptions. However there is an added cost, on average double the cost of
open cut construction.
• In the case of the Gerrard Street Watermain, the cost was justifiable because an
open cut construction would have created huge traffic issues in the downtown
corridor. It would have blocked the south access to the emergency entrances to
Princess Margaret Hospital, Mount Sinai Hospital and the Toronto Re-habilitation
Institute, on Murray Street. It would have also completely blocked the emergency
entrance to The Hospital for Sick Children on Elm Street, west of Elizabeth Street.
• Tunnel construction prevented the above noted traffic problems. Construction of
trunk watermains, all in tunnel, is recommended in areas with high volumes of
traffic.
19. Questions
• What type of TBM’s were used ?
• The contractor used two types of TBM’s:
A brand new 2550mm (102 inches) diameter, LOVAT TBM and an old 3000mm (120
inches) diameter, Robbins TBM, fabricated in Ohio, USA. Both TBM’s were open face
TBM’s for rock tunneling.
• What type of soil was encountered?
The 3.9 km of tunnel is in rock (shale). The watermain profile was designed to be
in the rock layer, which begins approximately 18 m below the surface, with at least 2
metres of rock cover. Transition between different layers of rock and soil is not
preferred in tunneling.
• Was there any subway crossings ?
Yes, the tunnel crossed the University/Spadina Subway Line and the Yonge Subway
Line. The road surface is approx. at 96 m of elevation, at University Ave. The Subway
invert is approx. at 82 m. The watermain invert is approx. at 71 m. The road surface is
approx. at 95 m of elevation at Yonge St. The subway invert is approx. at 86 m. The
watermain invert is approx. at 72 m. Approximately 8 m and 11 m of clearance
respectively.
