Appendix A-6 Springbank Dam Inspection

Appendix A-6 Springbank Dam Inspection

T E C H N I C A L M E M O R A N D U M

[INSERT JETT ID] LEGAL ENTITY (IF APPLICABLE) 1

Springbank Dam Decommissioning Alternatives Assessment

PREPARED FOR: Ashley Rammeloo, City of London

COPY TO: One River EA Steering Committee

PREPARED BY: Howie Henrikson, Jacobs

DATE: September 21, 2018

PROJECT NUMBER: 692537

REVISION NO.: 0

1.0 Purpose The purpose of this Technical Memorandum (TM) is to document the inspection of the Springbank Dam in London, Ontario performed on June 5, 2018. This inspection was competed to aid in the evaluation of the Springbank Dam Decommissioning Alternatives as part of the One River Master Plan Environmental Assessment (EA). The inspection informs the cost estimate for each alternative included in the EA for Springbank Dam. Reports summarizing previous inspections were reviewed as part of this exercise. This TM is not intended to be as detailed as the previously completed dam safety review inspections.

2.0 Introduction The One River EA develops a comprehensive plan for implementing various projects within the study area, which extends from downtown to just past the Springbank Dam along the Thames River through the City of London. Stage 1 of the One River EA identified alternatives for the Springbank Dam. These alternatives included Do Nothing, Free Flowing River, and Reinstating the Dam. The preferred option to restore a free-flowing river by decommissioning the dam was selected through a rigorous evaluation of each of the options based on their net social/cultural, environmental, technical and economic impacts.

This selection allowed the EA to move into Stage 2 and consider the remaining projects, as well as determine the preferred alternative for implementing a free-flowing river at the Springbank Dam. Alternatives considered include various degrees of dam decommissioning; do nothing, partial dam removal, and full dam removal. The purpose of this inspection, the review of previous inspection work, and the following analysis is to assist with estimating decommissioning costs for the Dam and provide input on what the extent of the decommissioning will be. This input will be used in the evaluation of each dam decommissioning alternative against a set of defined criteria as part of the One River EA.

2.1 Dam Decommissioning Alternatives

2.1.1 Do Nothing

The dam will be maintained in its current condition, with minimal upgrades or repairs. Currently, the Springbank Dam does not provide any water retention function as the gates are down on the riverbed, allowing water to flow freely over them and downstream. As part of the do nothing alternative, a minimum level of preventative rehabilitation is recommended, and a safety inspection program would be implemented to warn of any issues that arise with the Dam structure, components or associated erosion control works.

SPRINGBANK DAM DECOMMISSIONING ALTERNATIVES ASSESSMENT

2

2.1.2 Partial Dam Removal

The partial dam removal alternative includes removing and/or salvaging components of the dam such as the hydraulic system, electrical equipment, water retention gates and control room. It also includes stabilizing the dam structure and restoring the south riverbank with habitat improvements. This will allow the dam to become a fully passive and inoperable structure in the river. As part of the partial dam removal alternative, a safety inspection program would be implemented to warn of any issues that arise with the dam structure or associated erosion control works.

2.1.3 Full Dam Removal

Fully remove dam components and structure including gates, piers, and surrounding erosion control works. The impacted river bank and riverbed would be stabilized and fully restored, including habitat improvements.

2.2 Description and History of Springbank Dam The Springbank Dam is located on the Thames River in the City of London, Ontario. The dam was originally constructed in 1929. The structure consisted of 4 main bays separated by concrete abutment or pier walls. The main bays were split into 5 sub bays where timber and steel stop log assemblies could be positioned to check up the river. The superstructure and substructure were concrete elements or concrete encased steel beams in the case of the deck framing between concrete foundation elements. Stop logs were installed and removed with the use of a gantry crane running on rails supported by the steel beam elements. Interior stop log guides were constructed of hinged steel guide elements that could be rotated upstream while not in use.

The dam underwent a significant rehabilitation project in 1968. This project consisted of adding 50 mm of shotcrete facing to existing superstructure elements and 150 mm of shotcrete facing to pier walls and exposed abutment walls. In addition, a sheet pile wall was added on the upstream embankment at river left (south side). A concrete crib wall was added at river right (north side) upstream and downstream of the right abutment. In addition, a sluice gate was added to the left ½ of the left most main bay (bay 4). Use of the sluicing bay resulted in undesirable downstream erosion below it over time. Later, 3 of the sub bays in main bay 3 were fitting with overtopping gates to mitigate the erosion issues created by using the sluice gate.

A flood in the summer of 2000 caused significant damage and drove the decision to replace the stoplogs check scheme with hydraulically actuated steel gates. In 2008, the new gates were installed. Each gate occupied a main bay and are each approximately 14.94 m wide. The gates are hinged on the check dam floor on the upstream of the gates and hydraulic actuators on each side of each gate are used to raise and lower the dam. Damage occurred during initial raising of one of the gates in 2008 and the gates remained in the down position since that time.

2.3 Previous Inspections While in use as a water retention structure, the dam was on a 10-year inspection frequency for dam safety review. The structure condition was inspected as part of the dam safety review. The structure was inspected on June 19 and 20, 2001 by staff from Acres and the Upper Thames River Conservation Authority (UTTARA). The structure was inspected again on November 1 and 2, 2011 by Aecom and Watech Service Inc. During the 2011 inspection, the dam gates were in the down position (not impounding water). These inspection reports were reviewed to inform this exercise. In addition, a May 2001 memorandum was prepared by Riggs Engineering Ltd to address repairs to the North embankment.

These previous inspections provided an in-depth look at the dam structure, however as the most recent inspection was in 2011, the 2018 inspection provides an update on the condition of the dam structure and components. This inspection update is important as it was completed in the context of the One


3

River EA with the primary purpose of informing the evaluation of the Dam decommissioning alternatives, instead of exclusively focused on safety as the previous inspections had. This is useful as it addresses potential data gaps not captured in previous inspections, such as the details of the partial dam removal alternative. It also provides some insight into the rate of deterioration of the visible elements. Looking at removing components of the dam was not included in previous inspections but included in the scope of this inspection as the primary purpose was to inform the evaluation of alternatives. The scope to capture this data is included in the section below.

3.0 Scope The scope of this field investigation was to observe the condition of the existing Springbank Dam elements, limited to visual inspection only, and develop a list of the various elements of the facility to be considered in the decommissioning alternatives. The inspection was limited to visual observations that could be made from the dam deck, shoreline banks, and zodiac boat with an electric trolling motor. Two previous more detailed facility inspections were reviewed in advance to help differentiate where integrity issues might be developing or advancing since the last detailed inspection. The observations are used to inform the dam decommissioning alternatives. The observations are not made to support use of the facility to impound water which is beyond the scope of the field investigation.

Many of the loading demands on elements of the structure that might remain in the decommissioning alternatives will be significantly less than the original design function. However, many of the processes that corrode steel and deteriorate concrete will still occur. Examples of those processes are alternate wet and dry cycles, freeze/thaw cycles, and water intrusion. Remaining useful life predictions of the various facility elements are not an exact science, so any estimates made here are based on engineering judgement and inspector experience. Recommendations to stabilize or slow element deterioration will be made where appropriate in the decommissioning alternatives where dam elements might be retained in the alternatives.

4.0 Field Observations The table below (Table 1) summarizes the site conditions during the field investigation. The photo log from this investigation is included in Attachment A.

Table 1. Site Conditions Springbank Dam Decommissioning Alternatives Assessment for One River EA

Item Description

Location Springbank Dam site in Springbank Park along the Thames River in London, Ontario

Date June 5, 2018 10:00 am to 1:45 pm

Temperature 11°C

Weather Cloudy with moderate wind

Water Conditions Murky with 0.25 m to 0.5 m of visibility

Water Flow Low

Observation Staff S. Howie Henrikson/Jacobs, Mitch Jewson/Jacobs

Others Present Tom Mahood/Jacobs, Ashley Rammeloo/City of London (partial attendance)

Access Observations were made from the south river bank, top deck, and by boat with electric trolling motor.


4

4.1 Orientation For purposes of this TM, river left is the south side of the river (left side of river when looking downstream). The 2011 inspection report defined abutment 1 on river right, abutment 2 on river left, pier 1 on river right, pier 2 as center pier, and pier 3 on river left. This scheme is not consistent with the 2001 inspection report which considered the 3 interior elements as piers 2 through 4 but did number from the north end to the south end. For this write-up, substructure terminology will be north abutment, Piers 1 through 3 from north to south, and south abutment. Superstructure terminology is Spans 1 through 4 from north to south. Flow path terminology is Bays 1 through 4 from north to south.

4.2 Structure Elements The elements of the structure consist of concrete deck, control building, concrete substructure including abutments, piers and mat slab, hydraulic gates, and embankment.

Deck

• Light scaling of deck surface with some cement paste missing, exposing aggregate.

• Aggregate pop out with disintegrating aggregate observed, but not prevalent.

• Some previous locations of aggregate pop out have been infilled with two types of repair material. One type was a suspected polymer modified material, and the other type a poured rubber compound.

• Repair patches observed. Craze cracking apparent in repair patch. Some of the repair areas are not bonded to substrate as determined by sound techniques, but most are generally intact.

• Some minor hairline cracking observed in concrete deck between encased beams, staining not observed in deck from below.

• Top of embedded steel beams visible in superstructure. Two beams on downstream side and one beam on upstream side of the structure. Appears that a previously existing crane rail sitting on the beams was removed. Moderate sheet rusting and pitting observed on top of beam where rail previously sat. Grind line visible in top of beam flanges where welded connectors fastened the rail to the top of the beam.

• Abandoned stop log guide lifting access holes on upstream side of deck are covered over with welded down steel cover plates.

• Concrete encased beams generally have cracks and efflorescence visible on outside face of beam, approximately at mid-depth of encasement and on the underside of the beam. Underside of beams exhibit stalactite formations. Formations do not appear to be rust colored, but white and indicative of moisture exiting the cracks and precipitating material for the concrete in the form of stalactites.

• Visible areas of a corroded mesh on underside of downstream encased steel beams in Span 3. Consistent with description of 1968 rehab using 50 mm of shotcrete applied over a wire mesh on the deck support structure.

• Repair area under deck and beam encasement in downstream encased steel beams in Span 4. This area was associated with the sluice gate installed in approximately 1968 and removed in the 2008 gate installation. Part of repair appears to be spalled from below.

• Remnants of interior stop log support frame hinge assemblies remain between substructure elements on the downstream edge of the superstructure (piers and abutments). Typically, four in each span on downstream side, except at Span 4 where 1968 rehabilitation added a sluicing gate, leaving only two.


5

• Vegetation visible in efflorescing cracks on face of concrete encased steel beam Span 4.

• Railing system appears intact and in satisfactory condition and is generally consistent with the 1968 rehabilitation drawings. System may not be compliant with current pedestrian guard requirements.

Deck Joints

• Expansion joints were observed in the deck at Piers 1 and 3.

• Deck joints have two generations of a poured in joint filler material.

• Joints do not appear effective and are potential sources of water causing efflorescent staining on face of piers 1 and 3 below the deck superstructure. Some vegetation growing in joints observed.

Control Building

• Control building on left abutment (left side of river looking downstream) has two rooms accessed by one door. The most bankside room houses a generator and this space was part of the original 1929 construction. The riverside room houses hydraulic pumps for the gate hydraulic system and was added during the 2008 gate installation contract.

• Control building is of concrete masonry unit (CMU) construction with a brick veneer on portions of the outside face.

• First room has steel wide flange beams with metal deck for roof structure. Second room has steel joists with metal deck for roof structure.

• The bankside room sits on the abutment and embankment behind the abutment.

• The most riverside room was added in the 2008 hydraulic gate installation contract and sits on the bankside of superstructure Span 4.

Abutments

• Abutments are similar shape to piers on riverside face.

• Bankside is cast-in-place concrete bulkhead structure similar to a concrete crib wall infilled with soil. The bulkheads extend approximately 12 meters into stream bank at abutment 1 and approximately 15 meters into stream bank at abutment 2.

• Steep heavily wooded river bank on river right (Abutment 1) extending up to private property which is not visible from dam deck.

Piers

• Dam superstructure has 3 piers in river.

• Former stop log guides at piers have been infilled below the new seal plate installations.

• Piers exhibit some horizontal cracking with efflorescence. Face of piers appear to have been resurfaced since the original construction. Historical documents indicate a 150 mm shotcrete layer.

• Armoring on the upstream nose of the piers is intact with some surface pitting. Interface between armoring and anchor concrete has a slight shrinkage gap determined by sounding techniques.


6

• Downstream face of piers is fitted with a stainless-steel seal plate for the hydraulic gates to seal against in the raised position. Some void space sounded behind seal plates but potentially a minor shrinkage gap.

• Appears that upstream anchorage of seal plates was achieved with galvanized anchor bolts. This was determined by surface corrosion on nut and anchor rod threads close to the waterline.

Mat Slab

• The substructure foundation consists of a mat slab which is roughly 20.5 meters wide (upstream to downstream) and 68.6 meters long was generally not visible given the depth and clarity of the water.

Left abutment (abutment 2) embankment sheet pile

• Left side has a sheet pile wall system on upstream side allowing for level paved parking area adjacent to pedestrian path. Wall appears to have tiebacks. Historical documentation indicates Hoesch Section 155 piles with 1 ½ inch diameter tie backs. Sheet rusting of upstream face near ground line is prevalent and pitting is visible up to historical reservoir water elevation.

• Some ecology blocks align left with abutment to retain earth materials downstream of parking area and control building.

Right abutment (Abutment 1) embankment crib wall

• Right side has precast concrete crib wall adjacent to concrete abutment both upstream and downstream. The crib wall is infilled with earthen material.

• The river bank above the north embankment crib wall has been developed with homes. The stability of the embankment without the crib wall and dam abutment is beyond the scope of this exercise.

• Bushes, trees, and other vegetation is growing from the face of the crib walls.

5.0 Alternatives Discussion 5.1 Do Nothing This alternative consists of leaving the facility as it now sits in the gate down position with periodic visual observations to monitor the general condition of the structure and components. Elements of the structure will deteriorate over time. For example, continued rain and snowfall will advance deterioration of the concrete encasement around the deck girders and on the concrete piers. Growth of trees and bushes on the north bank concrete crib wall may pry apart that system and cause failures. Continued corrosion on the south bank sheet pile embankment wall at water line will compromise the integrity of that system. Failure of any of these elements will cause falling debris, putting river users at risk. Therefore, the do nothing alternative should include a minimum amount of maintenance and rehabilitation to maintain a safe facility. In addition, City staff should visually inspect the remaining structure at a reasonable frequency (once every 2 years) to monitor the condition and proactively address safety concerns that will develop as the structure ages.

A couple items should be considered as minimum maintenance tasks. The first includes prepping the top deck surface and applying an epoxy overlay system with broadcast sand. Preparation includes repairing any spalled, delaminated, deteriorated aggregate areas, and the deck area between the two steel beams on the downstream edge of the deck. Then the surface is shot blasted or high-pressure water blasted to achieve the proper surface roughness for the overlay product. This seals cracks which allow water to work its way through the deck or into the interface between the steel deck girders and the encasement concrete. Prevention of water travel through the concrete deck surface should extend


7

the useful life greatly. In addition, the system would experience little use, so would last much longer than a system applied on a bridge deck exposed to vehicle traffic. A second item is to rehab the two expansion joints on either end of the two superstructure center spans. This includes sealant and backer rod to keep water from traveling down the joints. These joint seal elements should also see a much greater life when compared to those on actual vehicle bridge decks. A third item is to remove the larger vegetation (trees and bushes) growing on the north bank crib wall. This could be an annual or biennial task to prevent vegetation from potentially prying the crib wall elements apart.

Other long-term maintenance items that should be monitored in a routine structure inspection are debris accumulation on the upstream nose of piers and gate arms, public safety features like fences and rails, overhead concrete spalling, scour evidence, and erosion evidence, to name some obvious ones. Mitigation to restore structural integrity will be required in the future at some point to maintain the facility in a safe condition or removal of unsafe features might be required.

5.2 Partial Dam Removal This alternative has a potential wide range of element removal to be considered. The partial dam removal alternative involves the demolition or salvaging of the gate panels, hydraulic actuator arms, gate hydraulic system, control building, and rehabilitation measures to slow/stop element deterioration of remaining elements to retain longer term integrity.

The river is approximately 70 to 80 meters wide around the dam. It is assumed that access from the north bank will not be obtained. Therefore, access will occur from the south bank. Due to the long reach, an access road into the river is anticipated or possibly some sort of floating work barge could be considered. It is anticipated that the access road is isolated from the river by a cofferdam. River flows will need to be maintained through the work area.

Each of the 4 gates are constructed of an upper and lower panel bolted together at the interface to make up one gate leaf. Each gate leaf is approximately 44,000 kg with approximately half the mass attributed to each panel. The gates also have baffles assemblies for fish passage that are removable via bolting. Two of gates have a baffle on one side and the other two have baffle pairs on each side for a total of 6 baffle pair assemblies. Each baffle pair assembly weighs approximately 644 kg. Each gate has an actuator cylinder on each side of the gate.

Access to remove these elements on the north side of the structure will likely require construction of an access road to get part way across the river, or access from a floating platform.

Rehabilitation measures include the deck sealing, deck joint sealing, and north bank crib wall maintenance tasks described in the do nothing alternative. In addition, a cathodic protection system could be installed on the south bank sheet pile wall. This system would include establishing electrical connectivity between all the existing sheet piles with a connecting weld and then installing a deep anode ground bed system. Other modifications to consider include upgrading the superstructure guardrail system to allow public access, but this item has not been costed in this exercise.

Concrete elements will slowly degrade over time even with the rehabilitation measure described in place. Similar to the do nothing alternative, a visual inspection by City staff should be completed on at least a 2-year frequency to address issues that may be developing into safety issues.

5.3 Full Dam Removal This alternative restores the river to a natural condition. It includes the removal of elements of the partial dam removal alternative and continuing with the removal of the superstructure, substructure piers and base slab, grouted riprap stream bed protection, north bank earth filled bulkhead walls and crib walls, south bank sheet pile and ecology block walls, and the restoration of the north and south river banks. The final stability of the north bank should be examined to consider residential structures


8

that have been built at the top of the bank to ensure north bank restoration only requires removal of the existing facility and regrading of the natural bank and not some additional stabilization of the slope.

The river is approximately 70 to 80 meters wide around the dam. It is assumed that access from the north bank will not be obtained. Therefore, access will occur from the south bank. Due to the long reach, an access road into the river is anticipated. It is anticipated that the access road is isolated from the river by a cofferdam. The area of any concrete demolition will also need to be isolated from the river with a cofferdam. River flows will need to be maintained past the isolated work areas and any access road features.

The full dam removal option will be more involved from a permitting perspective. The work will have to be phased to allow river flows through the project while other parts are isolated for removal. It is anticipated that vehicle and equipment access to the site will be restricted to the south bank. Removal is anticipated to start on the north bank working back to the south. Roughly the north half of the river and bank would be isolated with sheet piling and other cofferdam elements as appropriate to start the demolition.

Once the north bank is regraded and vegetated, isolation of the south half would occur to allow demolition of those elements and subsequent regrading and revegetation. It is anticipated that cofferdamming would include sheet piles, but could also include other products as installation could occur in areas of the south half already cleared of original dam elements covering the streambed (concrete slabs and grouted riprap).

6.0 Useful Life, Maintenance Recommendations and Cost Estimates 6.1 Useful Life The original structure was built in 1929. A major rehab occurred in 1968-1969 with refacing the pier/abutment elements with a 150 mm shotcrete facing. The underside of the deck was refaced with a 50 mm shotcrete facing. That was approximately a 40 year period until an extensive rehab was done. The cause behind deterioration that required fixing is not known. It could have been related to several issues including, but not limited to: freeze/thaw cycles, reactive aggregates, hydration issues within the original concrete matrix, cracking of the original concrete elements, and strength of the concrete. It seems likely that by the late 1960s any facing repair would be better suited to handle freeze/thaw and some of the other factors related to high strength integrity concrete were better known. However, the factors that led to an extensive repair after 40 years could be mitigated by refacing work or they could still be active but hidden due to the facing repairs. It is anticipated that the basic repair done in 1968 would have a service life of 20 to 75 years considering preventative maintenance is occurring for this structure. The full bay gates were added in 2008 which is another 40-year period. No additional significant rehabilitation of the concrete structure was done at that time lending to a conclusion that the structure was determined to be sound at that time. It has now been nearly 50 years since the major concrete facing activity was completed.

The concrete elements of the existing structure often most vulnerable to deterioration are those areas subjected to a fluctuating water line and those areas that have cracks allowing moisture penetration causing freezing expansion, providing water to deleterious reactions that may compromise the concrete matrix (Alkali silica reactivity, for example) and corrosion of reinforcing bars. These elements are the piers/abutments at the water line and the flat deck and deck joints.

In the areas of the substructure that could be reached to sound with a hammer, some soundings were somewhat hollow. Good solid concrete has more of ring to it when sounded with a hammer strike. The hollows sounds could indicate a few common causes such as punky concrete, debonding at the shotcrete facing interface to the original concrete substrate, or delamination’s within the concrete often caused by corroding reinforcing to name a few. The recommended measures to replace deck joints and


9

seal the deck will have significantly slow down the process of concrete deterioration of the deck spans and the pier/abutment tops.

Our opinion is that neglecting recommended concrete repairs will lead to the potential for falling concrete pieces in the 5 to 10-year time frame that will progressively become more severe and more frequent. Our opinion is the recommended repairs for the do nothing and partial removal alternatives extend the service life of the concrete portions another 15 to 25 years before anything more extensive like spalling/falling concrete occurs. Further deterioration will occur. Mitigation likely includes removing loose concrete pieces that cause falling hazards and removing projecting reinforcing bars that cause impalement concerns until such a point that overall stability is compromised by deterioration. The spans are anticipated to reach a stability concern before the pier/abutments.

Petrographic testing of concrete cores could be done to better understand the concrete matrix make-up for the original 1929 substrate and the 1968-1969 facing and if there might be some underlying issues that could be accelerating deterioration. That might help refine useful remaining service life of elements estimated based on experience and visual observations. This is only recommended if the ranges listed above are not definitive enough for comparison.

6.2 Maintenance Recommendations Minimum maintenance on the dam structure and surrounding earthworks is recommended in the near term for the do nothing and partial removal alternatives. These maintenance recommendations are intended to slow deterioration and extend the duration of the soundness of the facility.

For the full dam removal alternative, these maintenance items are not required as all dam components are to be removed. These requirements are based on defects observed in the inspection outlined above. These maintenance items will further the life of the dam, reduce risk and liability, and address health and safety concerns, and are listed below.

• Seal deck with epoxy overlay.

• Replace expansion joints.

• Remove north bank crib wall face vegetation.

• Repair north bank drainage.

6.3 Cost Estimates Table 2 summarizes the cost estimates made for each alternative. A more detailed cost estimate can be found in Attachment B. The following assumptions were considered in development of the cost estimates:

• Costs do not include a recommended biennial safety inspection (approximate cost $10,000) for the do nothing and partial dam removal alternatives.

• Estimates are considered a Class 5 (concept screening) Cost Estimate. They are considered accurate to +100 percent to –50 percent.

• Cost estimate assumes August 2018 prices. Estimate excludes escalation or inflation.

• The cost estimate assumes that a 10-man crew can complete the full removal within 8 months if working 50-hour work weeks.

• No construction access is available from the north side of dam. All hauling and trucking is to be staged on the south side of dam through Springbank Park.


10

• For costing purposes, a floating platform was priced for accessing the north bank to complete the demolition. Contractor may opt for a different solution for accessing the north side of the dam.

• Contractor will construct an access ramp and landing on south side bank for construction access.

• Contractor will construct cofferdam to isolate north side of dam. Cofferdam will need to be constructed from a floating platform due to no access from the north side.

• A floating platform will be used to get equipment/personnel and construction debris to and from the north bank from the south bank.

• Suggested Construction Phasing:

o Complete all work and demolition on North Side of Dam.

o Remove North Side cofferdam.

o Contractor will construct cofferdam to isolate south side of dam.

o Complete all work and demolition on South Side of Dam.

• Costs do not include Design and Engineering, Construction Management, Permitting Costs or Taxes.

The cost comparisons of the alternatives are for initial cost. Some of the items in the do nothing and partial dam removal alternatives have an anticipated service life. An attempt has not been made to compare cost of the alternatives based on a given period.

Table 2. Alternatives Cost Comparison Details Springbank Dam Decommissioning Alternatives Assessment for One River EA

Alternative Maintenance Intervals (years)

Description of Work Required Approximate Cost

Do Nothing $408,000

25 Seal deck with epoxy overlay $195,000

20 Replace Expansion Joints $14,000

10 Remove north bank crib wall face vegetation $18,000

25 Repair north bank drainage $129,000

25 South Bank Sheet Pile Cathodic Protection $52,000

Partial Dam Removal

$2,236,000

25 Seal deck with epoxy overlay $195,000

20 Replace Expansion Joints $14,000

10 Remove north bank crib wall face vegetation $18,000

25 Repair north bank drainage $129,000

25 South Bank Sheet Pile Cathodic Protection $52,000

N/A Remove 4 gate panels and hydraulic actuators $749,000

N/A Remove hydraulic system conduit routing $69,000


11

Table 2. Alternatives Cost Comparison Details Springbank Dam Decommissioning Alternatives Assessment for One River EA

Alternative Maintenance Intervals (years)

Description of Work Required Approximate Cost

N/A Remove gate pumps and motors $182,000

N/A Remove control building on south end $45,000

NA Construction Barge $167,000

N/A Removal of South Side Grouted Rip Rap $167,000

N/A Grout Blanket Removal $51,000

N/A Regrade and Revegetate South Bank $398,000

Full Dam Removal $5,613,000

N/A Remove 4 gate panels and hydraulic actuators $749,000

N/A Remove hydraulic system conduit routing $69,000

N/A Remove gate pumps and motors $182,000

N/A Remove control building on south end $45,000

N/A Access road and crane pad in river $402,000

N/A North side Demolition $2,594,000

N/A South Side Demolition $1,095,000

N/A Regrading and Revegetating River Banks $477,000

7.0 Limitations This technical memorandum has been prepared in accordance with generally accepted civil engineering practices for the exclusive use of The City of London. Third parties cannot rely upon the findings and conclusions presented without express written consent of CH2M HILL and The City of London through an extension of reliance using a reliance letter signed by both parties. CH2M HILL accepts no responsibility for damages, if any, incurred by any third party as a result of decisions made or actions based on this technical memorandum. The findings and conclusions regarding the structure condition and cost estimate information are based solely on the extent of observations and information gathered during this limited assessment. Conclusions made in regard to the condition of the structure are based on a limited site inspection and review of relevant site inspection documentation.

Site conditions, events, and observations described in this memorandum are those observed at the time of the inspection. This is a technical report and is not a legal representation or interpretation of environmental laws, rules, regulations, or policies of governmental agencies.

All findings and conclusions stated in this memorandum are based on facts and circumstances as they existed during the preparation of this memorandum. Should additional environmental or related information become available after the date of this memorandum, CH2M HILL reserves the right to review this new information and modify, as deemed necessary, any or all of the opinions presented in this document.

Estimated useful life of elements is based on practical experience gained with similar type structures. Existing concrete elements have not been petrographically tested to determine if there are inherent


12

deterioration issues within the concrete matrix. Final stability of the north bank after regrading for full dam removal alternative has not been vetted at this stage of the process.

PHOTO LOG

CH2M HILL CANADA LIMITED 1

Photo 1 – Aggregate Popout in Top Deck

PHOTO LOG


Photo 2: Degraded Aggregate in Top Deck

PHOTO LOG


Photo 3: Typical Transverse Cracking in Deck

PHOTO LOG


Photo 4: Scaling Observed on Top Deck

PHOTO LOG


Photo 5: Typical Craze Cracking in Deck Patch

PHOTO LOG


Photo 6: Typical Corrosion Product on Upstream Steel Beam Top Flange

PHOTO LOG


Photo 7: Typical Sheet Rust Corrosion Product on Top Flange of Upstream Steel Beam Flange

PHOTO LOG


Photo 8: Typical Condition of Adjacent Downstream Deck Support Steel Beams

PHOTO LOG


Photo 9: Deck Joint Condition

PHOTO LOG



PHOTO LOG



PHOTO LOG


Photo 12: Control Building Entrance Door

PHOTO LOG


Photo 13: Scaling of Concrete Slab in Left Abutment Embankment Area

PHOTO LOG


Photo 14: Upstream View of Left Most Gate Bay

PHOTO LOG


Photo 15: Upstream View of Left of Center Gate Bay

PHOTO LOG


Photo 16: Upstream View of Right of Center Gate Bay

PHOTO LOG


Photo 17: Upstream View of Right Most Gate Bay

PHOTO LOG


Photo 18: Downstream View of All Bays

PHOTO LOG


Photo 19: Downstream View of Left Most Span at Left Abutment

PHOTO LOG


Photo 20: Downstream View of Left Most Span at Former Sluice Gate Pier Location

PHOTO LOG


Photo 21: Underside of Deck in Left Most Span at Former Sluice Gate Pier

PHOTO LOG


Photo 22: Underside of Downstream Deck Support Beams Exposed/Corroding Mesh in Span Right of Center

PHOTO LOG


Photo 23: Underside of Deck Showing Cracking/Efflorescing on Underside of Upstream and Downstream Beams

PHOTO LOG


Photo 24: Debris Accumulation on Upstream Nose of Left Most Pier

PHOTO LOG


Photo 25: Typical Pitting on Pier Armoring on Upstream Pier Nose

PHOTO LOG


Photo 26: Typical Pier Face Finish with Cracking and Staining

PHOTO LOG


Photo 27: Typical Craze Cracking and Stained Cracks on Pier Face

PHOTO LOG


Photo 28: Delaminating Surface Finish on South Side of Center Pier

PHOTO LOG


Photo 29: Galvanized Mild Steel Anchorage of Stainless Steel Gate Side Seal Plate

PHOTO LOG


Photo 30: Top of Right Most Pier Spalling Condition

PHOTO LOG


Photo 31: Top of Right Abutment Nose Spalling Condition

PHOTO LOG


Photo 32: View of Right Abutment Cracking and Staining

PHOTO LOG


Photo 33: Left Abutment Downstream Embankment Bank Side View

PHOTO LOG


Photo 34: Left Abutment Downstream Embankment River Side View

PHOTO LOG


Photo 35: Left Abutment Embankment Upstream Sheet Pile Wall

PHOTO LOG


Photo 36: Left Abutment Embankment Sheet Pile Wall Corrosion

PHOTO LOG


Photo 37: Left Abutment Embankment Sheet Pile Wall Tie Back Anchor

PHOTO LOG


Photo 38: Right Abutment Downstream Embankment Concrete Crib Wall

PHOTO LOG


Photo 39: Right Abutment Upstream Embankment Concrete Crib Wall

Project: Estimator:

Client: Estimate Date:

Location: Revision:

Sheet # Description Qty UM Labor Equipment Material Subcontract Other Total Allocated Total Low -50% High 100%

2.082

01 Do Nothing 1.00 LS $49,375.00 $22,225.00 $122,250.00 $1,980.00 $0.00 $195,830.00 $407,718.06 $200,000.00 $820,000.00

49,375.00 / LS 22,225.00 / LS 122,250.00 / LS 1,980.00 / LS 0.00 / LS 195,830.00 / LS 407,718.06 / LS

Toronto, ON Adj. Factor $29,961.99 15.3%

General Conditions $13,708.10 7.0%

Contractor OH $19,583.00 10.0%

Contractor Profit $9,791.50 5.0%

Insurance & Bonds $2,937.45 1.5%

Subtotal $271,812.04

Contingency $135,906.02 50.0%

Subtotal $407,718.06

Escalation $0.00 0.0%

Total $407,718.06


2.082

02 Partial Dam Removal 1.00 LS $320,212.68 $463,634.51 $122,250.00 $167,722.54 $0.00 $1,073,819.72 $2,235,692.65 $1,120,000.00 $4,470,000.00

320,212.68 / LS 463,634.51 / LS 122,250.00 / LS 167,722.54 / LS 0.00 / LS 1,073,819.72 / LS 2,235,692.65 / LS



Contractor OH $107,381.97 10.0%



Subtotal $1,490,461.77

Contingency $745,230.88 50.0%

Subtotal $2,235,692.65


Total $2,235,692.65


2.082

03 Full Dam Removal 1.00 LS $833,466.20 $1,449,443.40 $98,000.00 $315,198.24 $0.00 $2,696,107.85 $5,613,296.53 $2,810,000.00 $11,230,000.00

833,466.20 / LS 1,449,443.40 / LS 98,000.00 / LS 315,198.24 / LS 0.00 / LS 2,696,107.85 / LS 5,613,296.53 / LS



Contractor OH $269,610.78 10.0%



Subtotal $3,742,197.69

Contingency $1,871,098.84 50.0%

Subtotal $5,613,296.53


Total $5,613,296.53

ESTIMATE SUMMARY Class 5 Accuracy Range

Class 5 Accuracy Range

Class 5 Accuracy Range

Springbank Dam Tom Jones/CVO

City of London 9/10/2018

Ontario, Canada R04

Property of JACOBS ‐ All Rights Reserved ‐ Copyright 2018

Project: Estimator:


Location: Revision:

Code Description Qty UM 2.082

Seal deck with epoxy overlay 510 M2 85 25.00 150.00 6 12,750.00 50.00 8.33 4,250.00 150.00 76,500.00 183.33 93,500.00 194,667.00

Replace Expansion Joints 15 M 30 300.00 150.00 0.5 4,500.00 50.00 100.00 1,500.00 50.00 750.00 450.00 6,750.00 14,053.50

Remove north bank crib wall face vegetation 660 M2 16.5 6.25 250.00 40 4,125.00 150.00 3.75 2,475.00 3.00 1,980.00 13.00 8,580.00 17,863.56

Repair north bank drainage 1 LS 80 20,000.00 250.00 0.0125 20,000.00 150.00 12,000.00 12,000.00 30,000.00 30,000.00 62,000.00 62,000.00 129,084.00

Cathodic Protection South Side 1 LS 40 8,000.00 200.00 0.025 8,000.00 50.00 2,000.00 2,000.00 15,000.00 15,000.00 25,000.00 25,000.00 52,050.00

Sheet Qty UM

1.00 LS 49,375.00 $49,375.00 22,225.00 $22,225.00 122,250.00 $122,250.00 1,980.00 $1,980.00 0.00 $0.00 195,830.00 $195,830.00 $407,718.06

Sub Unit Sub Total Other Unit Other Total Total Unit

Tom Jones/CVO


Ontario, Canada R04

1 Do NothingTotal CH

Labor Unit Cost

Crew $/HR Crew Units/CH

Labor Total

Springbank Dam

Total CostEquip Unit Crew $/HR Equip Unit Equip Total Material Unit

Material TotalESTIMATE DETAIL

Grand Total

Property of JACOBS ‐ All Rights Reserved ‐ Copyright 2018 2 of 4 7:46 AM 9/10/2018

Project: Estimator:


Location: Revision:

Tom Jones/CVO


Ontario, Canada R04

Springbank Dam

ESTIMATE DETAIL


Seal deck with epoxy overlay 510 M2 85 25.00 150.00 6 12,750.00 50.00 8.33 4,250.00 150.00 76,500.00 183.33 93,500.00 194,667.00

Replace Expansion Joints 15 M 30 300.00 150.00 0.5 4,500.00 50.00 100.00 1,500.00 50.00 750.00 450.00 6,750.00 14,053.50

Remove north bank crib wall face vegetation 660 M2 16.5 6.25 250.00 40 4,125.00 150.00 3.75 2,475.00 3.00 1,980.00 13.00 8,580.00 17,863.56

Repair north bank drainage 1 LS 80 20,000.00 250.00 0.0125 20,000.00 150.00 12,000.00 12,000.00 30,000.00 30,000.00 62,000.00 62,000.00 129,084.00

Cathodic Protection South Side 1 LS 40 8,000.00 200.00 0.025 8,000.00 50.00 2,000.00 2,000.00 15,000.00 15,000.00 25,000.00 25,000.00 52,050.00

Remove 4 gate panels and hydraulic actuators 4 EA 160 20,000.00 500.00 0.025 80,000.00 1,500.00 60,000.00 240,000.00 10,000.00 40,000.00 90,000.00 360,000.00 749,520.00

Remove hydraulic system conduit routing 1 LS 40 16,000.00 400.00 0.025 16,000.00 300.00 12,000.00 12,000.00 5,000.00 5,000.00 33,000.00 33,000.00 68,706.00

Remove gate pumps and motors 4 EA 96 9,600.00 400.00 0.041666667 38,400.00 300.00 7,200.00 28,800.00 5,000.00 20,000.00 21,800.00 87,200.00 181,550.40

Remove control building on south end 1 LS 24 9,600.00 400.00 0.041666667 9,600.00 300.00 7,200.00 7,200.00 5,000.00 5,000.00 21,800.00 21,800.00 45,387.60

Import Barge 40 HR 40 500.00 500.00 1 20,000.00 1,500.00 1,500.00 60,000.00 2,000.00 80,000.00 166,560.00

Demolition South Side of Dam

Downstream grouted riprap 2 ft thick 750 M3 93.7858 50.00 400.00 8 37,514.33 300.00 37.50 28,135.75 10.00 7,502.87 97.50 73,152.94 152,304.43

Upstream grouted riprap 2 ft thick 74 M3 9.24587 50.00 400.00 8 3,698.35 300.00 37.50 2,773.76 10.00 739.67 97.50 7,211.78 15,014.92

Grout Blanket Removal 250 M3 31.25 50.00 400.00 8 12,500.00 300.00 37.50 9,375.00 10.00 2,500.00 97.50 24,375.00 50,748.75

Regrade and revegetate south bank 2,600 M2 130 12.50 250.00 20 32,500.00 250.00 12.50 32,500.00 20.00 52,000.00 45.00 117,000.00 243,594.00

Regrade and revegetate south bank downstream 1,650 M2 82.5 12.50 250.00 20 20,625.00 250.00 12.50 20,625.00 20.00 33,000.00 45.00 74,250.00 154,588.50

Sheet Qty UM

1.00 LS 320,212.68 $320,212.68 463,634.51 $463,634.51 122,250.00 $122,250.00 167,722.54 $167,722.54 0.00 $0.00 1,073,819.72 $1,073,819.72 $2,235,692.65

Total CostMaterial Unit

Material Total Sub Unit Sub Total Other Unit Other TotalLabor Total Equip Unit Crew $/HR Equip Unit Equip Total2 Partial Dam Removal

Total CH

Labor Unit Cost


Total Unit Total Cost


Project: Estimator:


Location: Revision:

Tom Jones/CVO


Ontario, Canada R04

Springbank Dam

ESTIMATE DETAIL


Remove 4 gate panels and hydraulic actuators 4 EA 160 20,000.00 500.00 0.025 80,000.00 1,500.00 60,000.00 240,000.00 10,000.00 40,000.00 90,000.00 360,000.00 749,520.00

Remove hydraulic system conduit routing 1 LS 40 16,000.00 400.00 0.025 16,000.00 300.00 12,000.00 12,000.00 5,000.00 5,000.00 33,000.00 33,000.00 68,706.00

Remove gate pumps and motors 4 EA 96 9,600.00 400.00 0.041666667 38,400.00 300.00 7,200.00 28,800.00 5,000.00 20,000.00 21,800.00 87,200.00 181,550.40

Remove control building on south end 1 LS 24 9,600.00 400.00 0.041666667 9,600.00 300.00 7,200.00 7,200.00 5,000.00 5,000.00 21,800.00 21,800.00 45,387.60

Construct Cofferdam for Northside Work Area

Import Barge 40 HR 40 500.00 500.00 1 20,000.00 1,500.00 1,500.00 60,000.00 2,000.00 80,000.00 166,560.00

Construct Cofferdam 140 M 93.3333 333.33 500.00 1.5 46,666.67 1,500.00 1,000.00 140,000.00 350.00 49,000.00 1,683.33 235,666.67 490,658.00

Pump and Dry Work Area 1 LS 40 10,000.00 250.00 0.025 10,000.00 250.00 10,000.00 10,000.00 20,000.00 20,000.00 41,640.00

Demolition North Side of Dam

dam base slab concrete 860 M3 107.5 50.00 400.00 8 43,000.00 300.00 37.50 32,250.00 10.00 8,600.00 97.50 83,850.00 174,575.70

2 exterior piers (abutments) 260 M3 32.5 50.00 400.00 8 13,000.00 300.00 37.50 9,750.00 10.00 2,600.00 97.50 25,350.00 52,778.70

right bank bulkhead foundation 60 M3 7.5 50.00 400.00 8 3,000.00 300.00 37.50 2,250.00 10.00 600.00 97.50 5,850.00 12,179.70

right bank bulkhead walls 125 M3 15.625 50.00 400.00 8 6,250.00 300.00 37.50 4,687.50 10.00 1,250.00 97.50 12,187.50 25,374.38

Deck Section 100 M3 12.5 50.00 400.00 8 5,000.00 300.00 37.50 3,750.00 10.00 1,000.00 97.50 9,750.00 20,299.50

north bank concrete crib wall footing 350 M3 43.75 50.00 400.00 8 17,500.00 300.00 37.50 13,125.00 10.00 3,500.00 97.50 34,125.00 71,048.25

north bank concrete retaining wall 40 M3 5 50.00 400.00 8 2,000.00 300.00 37.50 1,500.00 10.00 400.00 97.50 3,900.00 8,119.80



Barge During Demolition 328 HR 327.5 500.00 500.00 1 163,750.00 1,500.00 1,500.00 491,250.00 2,000.00 655,000.00 1,363,710.00

Construct Cofferdam for Southside Work Area

Construct Cofferdam 140 M 93.3333 333.33 500.00 1.5 46,666.67 1,500.00 1,000.00 140,000.00 350.00 49,000.00 1,683.33 235,666.67 490,658.00

Pump and Dry Work Area 1 LS 40 10,000.00 250.00 0.025 10,000.00 250.00 10,000.00 10,000.00 20,000.00 20,000.00 41,640.00

Demolition South Side of Dam

dam base slab concrete 854 M3 106.757 50.00 400.00 8 42,702.99 300.00 37.50 32,027.24 10.00 8,540.60 97.50 83,270.82 173,369.85

3 Interior Piers 552 M3 69.0157 50.00 400.00 8 27,606.30 300.00 37.50 20,704.72 10.00 5,521.26 97.50 53,832.28 112,078.82

Left bank bulkhead foundation 66 M3 8.31043 50.00 400.00 8 3,324.17 300.00 37.50 2,493.13 10.00 664.83 97.50 6,482.14 13,495.81

left bank bulkhead walls 131 M3 16.3548 50.00 400.00 8 6,541.93 300.00 37.50 4,906.45 10.00 1,308.39 97.50 12,756.77 26,559.59

Deck Section 92 M3 11.5078 50.00 400.00 8 4,603.14 300.00 37.50 3,452.35 10.00 920.63 97.50 8,976.11 18,688.27



Grout Blanket Removal 250 M3 31.25 50.00 400.00 8 12,500.00 300.00 37.50 9,375.00 10.00 2,500.00 97.50 24,375.00 50,748.75

Install access road and crane pad in river 530 M2 44.1667 33.33 400.00 12 17,666.67 300.00 25.00 13,250.00 150.00 79,500.00 208.33 110,416.67 229,887.50

Remove part of access road and re-establish crane pad fo 1 LS 24 9,600.00 400.00 0.041666667 9,600.00 300.00 7,200.00 7,200.00 16,800.00 16,800.00 34,977.60

Remove access road and crane pad into river 1 LS 80 32,000.00 400.00 0.0125 32,000.00 300.00 24,000.00 24,000.00 10,000.00 10,000.00 66,000.00 66,000.00 137,412.00

Regrade and revegetate north bank 840 M2 42 12.50 250.00 20 10,500.00 250.00 12.50 10,500.00 20.00 16,800.00 45.00 37,800.00 78,699.60

Regrade and revegetate south bank 2,600 M2 130 12.50 250.00 20 32,500.00 250.00 12.50 32,500.00 20.00 52,000.00 45.00 117,000.00 243,594.00

Regrade and revegetate south bank downstream 1,650 M2 82.5 12.50 250.00 20 20,625.00 250.00 12.50 20,625.00 20.00 33,000.00 45.00 74,250.00 154,588.50

Sheet Qty UM

1.00 LS 16669.3 833,466.20 $833,466.20 1,449,443.40 $1,449,443.40 98,000.00 $98,000.00 315,198.24 $315,198.24 0.00 $0.00 2,696,107.85 $2,696,107.85 $5,613,296.53

Sub Total Other Unit Other Total Total Unit Total CostEquip Unit Crew $/HR Equip Unit Equip Total Material Unit

Material Total3 Full Dam Removal

Total CH

Labor Unit Cost


Labor Total Sub Unit Total Cost


Documents

Appendix A-6 Springbank Dam Inspection