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Date: September 13, 2019

Addendum # 3

Request for Proposals P24.2019

Title: Halifax Water Dam Safety Review (2019) To All Proponents of P24.2019: Please note: the following addendum applies to P24.2019 and shall be taken into consideration when preparing proposal documents. With regards to a previous question about dam break studies being completed. Halifax Water has completed dam failure inundation mapping for the following structures:

Chain Lake Dam

Pockwock Dam

Lake Lamont Dam This information will be made available to the successful proponent. Question 1: We would like to clarify the RFP requirements with regards to looking at the impacts of climate change on the PMP/PMF for the six dams. This will be a significant task wherein you have to effectively combine the two types of analysis (climate projections & PMP) that each have deep uncertainty and many assumptions associated with them. We would need the analysis (numbers, inputs etc) conducted by Hatch to do it properly, not just the outputs from their reporting. Will that information be made available to the successful consultant?

Answer 1: The information provided in Appendix F is what Halifax Water has on record for previous Dam Safety Reviews completed in 2004 and 2012. This information will be provided to the successful proponent in the same format. Background calculations and assumptions by Hatch are not available.

Question 2: It would be very helpful if Halifax Water would specify what they want from this climate change review. A full PMP under climate change, or more of an indication of whether such an analysis may be required? There is a significant difference in the level of effort (and cost) between these deliverables.

Answer 2: As part of the Dam Safety Review scope proponents will develop PMP and PMF data using information provided in Appendix F. This information does not include any future climate change predictions. Halifax Water is requesting proponents perform a risk assessment to the PMP and PMF information developed for the dam safety review. Proponents are encouraged to explore various sources on guidance for climate change impacts, including information provided

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by Environment Canada or other credible agencies. Section 4.3 of the RFP states that the risk assessment shall include:

a. Impact of climate change driven precipitation and snowfall projections on PMF/PMP hydrographs. b. Review current climate change projections and determine if any change to current dam classifications is justified.

c. Review current climate change projections and determine risk to public safety or drinking water supply on any of Halifax Water’s currently owned/operated dams.

The climate change component of the work is listed as provisional. Halifax Water may choose to add this to the scope of work at its discretion. Proponents are encouraged to provide a scope of work as part of their proposal response to meet the requirements outlined in the RFP and clarification information provided with this addendum. It is not a requirement of the RFP to complete the Dam Safety Review twice with two sets of PMP and PMF data. At a minimum, Halifax Water anticipates that PMF/PMP hydrographs will be developed which include climate change impacts. Proponents shall review and discuss differences between these PMF/PMP hydrographs and ones developed for the Dam Safety Review. Also for consideration, proponents should analyze (without performing an additional Dam Safety Review) significant differences which could warrant a change to Dam Safety Classifications as a result of the climate change impacted PMF/PMP hydrographs. Proponents should review and present a discussion of risks associated with using PMF/PMP hydrographs that do not include climate change information. Proponents shall include all calculations, assumptions and reference material in an appendix of the technical memo. A signed copy of each Addendum must also be included with the proposal submission. Failure to include this Addendum may be cause for rejection. If you have any questions, please contact our office by email at procurement@halifaxwater.ca.

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ALL OTHER SPECIFICATIONS, TERMS AND CONDITIONS REMAIN UNCHANGED. Acknowledgement by Proponent: Company Name: _________________________ Print Name: _____________________________ Signed: ______________________________ Date: ______________________________

End of Addendum #3

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Date: September 10, 2019

Addendum # 2

Request for Proposals P24.2019

Title: Halifax Water Dam Safety Review (2019) To All Proponents of P24.2019: Please note: the following addendum applies to P24.2019 and shall be taken into consideration when preparing proposal documents. The closing date and time shall be extended to Thursday September 19, 2019 at 2:00 p.m., Atlantic Time. A signed copy of each Addendum must also be included with the bid submission. Failure to include this Addendum may be cause for rejection. If you have any questions, please contact our office by email at procurement@halifaxwater.ca.

ALL OTHER SPECIFICATIONS, TERMS AND CONDITIONS REMAIN UNCHANGED.

Acknowledgement by Bidder: Company Name: _________________________ Print Name: _____________________________ Signed: ________________________________ Date: __________________________________

End of Addendum #2

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Date: September 6, 2019

Addendum # 1

Request for Proposals P24.2019

Title: Halifax Water Dam Safety Review (2019) To All Proponents of P24.2019: Please note: the following addendum applies to P24.2019 and shall be taken into consideration when preparing proposal documents. Question 1: Could you please indicate the expected delivery times for the DSR results and reports? Answer 1: Halifax Water expects that the work required for the DSR would be completed by proponents as quickly as possible. Field work is anticipated to be completed in the fall of 2019 with DSR results and report to be complete in draft form early in 2020. Question 2: Could you please indicate if dam break modelling has been done in the past for the six dams? When and with what software and if the models or results are available? Answer 2: Dam break modeling has not been completed as part of past dam safety reviews. Question 3: Are previously prepared hydrologic models available? What software was used for them? Answer 3: Previously prepared hydrologic models are not available. Proponents are instructed to use information provided. Question 4: Is LiDAR data available? If so, could you please provide a map with the extent of the area covered by LiDAR data? Answer 4: LiDAR data is not available through Halifax Water. Topographic surveys were conducted at each dam site in 2012 and are included as an appendix to the DSR report. Question 5: Do you expect that an underwater inspection of the structures will be conducted as part of the DSRs? Has it been done before, at what structures and when? Answer 5: There has not been underwater inspections performed as part of previous Dam Safety Reviews. It is the proponent’s responsibility to include appropriate

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inspections outlined in CDA Dam Safety Review requirements. Question 6: Please confirm the following information can be obtained upon request after winning the project:

Geotechnical investigation reports/information for all dams, and electronic files;

Past record, or measurements on ice pile-up/accumulations;

Structural/civil drawings and electronic files for all dams;

Stop log/gate drawings. Answer 6:

Geotechnical investigation reports are not available for all dams.

Ongoing dam inspection records and monitoring information will be made available to the successful proponent

As-built drawing information in electronic form for all dams is available

Stop log/gate drawing information are shown on as-built drawings Question 7: RFP 4.2.a.v “Review and document existing records….”: Please describe the type of record documents available to review and quantify the documents available. Answer 7: Halifax Water has electronic versions of as-built drawing information which will be made available to the successful proponent. The 2012 Dam Safety Review also includes topographical survey information completed at dam locations. Question 8: Confirm that all record documents will be provided upon contract award and in electronic format (PDF, etc). Answer 8: Halifax Water will make record information available to the successful proponent in electronic format. Question 9: Please list the equipment at each site that has records verifying the equipment was tested and/or operated within the last year. Answer 9: Halifax Water will make inspection information available to the successful proponent. Question 10: RFP 4.2.a.xiii “Review the 2012 Halifax Water Dam Safety Report…”: Confirm if this report is the same as the MECO 2012 report referred to in section 2.1 of the RFP. Answer 10: The reports listed above are the same report. Question 11: Please confirm at which dams it will be possible to fully open the largest sluice at high water levels. Answer 11: Halifax Water cannot confirm at this time where this will be possible. Dam

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inspection records will be made available to the successful proponent. Question 12: Please confirm if it will be possible to partially open/close (ie operate) each type of sluice at each dam. Answer 12: Halifax Water cannot confirm at this time where this will be possible. Dam inspection records will be made available to the successful proponent.

Question 13: Appendix E, general to various dams: Please describe how stop logs are removed/installed (mobile crane, etc). Answer 13: Stop logs are removed/installed through manual means with the exception of Lake Major Dam which requires a mobile crane. Question 14: Please indicate which gates/valves have stop log gains upstream or downstream of the gates/valves to isolate them for service? Answer 14: East Lake Dam, Lake Major Dam, Pockwock Dam and Bayers Brook have stop log gains upstream of the gates/valves. Question 15: Please describe the mechanism for actuating the gates/valves at each dam (hand crank, hand wheel, wire rope hoist, portable electric actuator, etc). Answer 15: Most gates and valves are manually operated with a hand wheel. Lake Major Dam has electrically controlled actuators. Question 16: Please describe the extent of electrical equipment at each dam (gate/gain heating, site lighting, instruments for water level measurement, remote communication systems, etc). Answer 16: Larger dams at Lake Major and Pockwock have remote communication/monitoring and an electrical service. The other locations are remote and have no electrical equipment. Question 17: Is there any back-up power supply at the sites (Diesel genset, batteries, etc)? Answer 17: There is no back-up power supply at the sites. Question 18: Appendix E, East Lake Dam: a. Please clarify if “a 0.9 m wide sluice gate” mentioned in the second sentence of the description is the same as “the gate valve” mentioned in the fourth sentence. If they are not the same thing, please describe the “gate valve” (type of valve, purpose, etc). Answer 18: The gate valve is the same as the sluice gate.

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Question 19: Appendix E, Bayers Brook Diversion Dam: a. Please indicate if both sluice gates are for flow control and confirm if one is for the diversion sewer and one is for the diversion channel. Answer 19: Both sluice gates are for flow control. One is for the diversion sewer and the other is for the diversion channel. Question 20: Based on the Diversion Structure photo in the RFP it appears that there is an adjustable weir at the inlet to the structure. Please confirm. And if it is adjustable please describe how height is adjusted. Answer 20: The weir is fixed and is not adjustable. Question 21: Appendix E, Chain Lake Dam: Please describe the 500 mm valve (sluice gate, butterfly valve, how it is actuated, etc). Answer 21: The valve is manually operated. Question 22: Please describe what is inside the north and south gate houses (hoists for actuating gates, type of gates, quantity of gates, purpose of gates, gains for isolating gates, stop logs for gate isolation, etc). Answer 22: The north and south gate houses described in the narrative are not used for dam operation. Question 23: Appendix E, Lake Major Dam - Please confirm that equipment at the dam is limited to the two 1 m x 1 m sluice gates. Please describe the gates (type of gates, how actuated, etc). Answer 23: In addition to the sluice gates, the adjustable fish ladder weirs have electrically controlled actuators. Question 24: Appendix E, Pockwock Dam: a. Please describe the three 1.5 m x 1.5 m gates (type of gates, how actuated, etc). Answer 24: The gates have electronic and manually controlled actuators. Question 25: Section 3.1 Life Cycle Approach for the noted RFP. Please clarify how this section is applicable to the dam safety review in terms providing “a solution with the lowest life cycle cost” and “optimal design solution”? Answer 25: Halifax Water anticipates that any recommendations to maintain compliance with CDA requirements as a result of the 2019 Dam Safety Review will consider low life cycle costs and an optimal solution and/or recommendation where applicable.

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Question 26: Please indicate what electrical equipment is in each dam for operation of water control structures; are there drawings available? Answer 26: See answer in question 16. There are as built records available for each dam location. Question 27: Are previous PMF analyses available? Answer 27: The previous PMF analysis is included in the 2012 DSR report. Question 28: Please confirm that a new PMF calculation is required.

Answer 28: Proponents are expected to produce new PMF calculations based on information provided in the RFP. Proponents will include all calculations and assumptions in a separate appendix to the DSR as outlined in the requirements of the RFP.

Question 29: Does Halifax Water require an audit type DSR (in which the adequacy of previous evaluations is assessed) or are new stability calculations (from scratch) required? Answer 29: A review of previous 2012 stability results and production of new stability calculations are required. Proponents are to include all design review notes, calculations, spreadsheets, reference material and assumptions used in the analysis and to support conclusions in the dam safety review. Question 30: Are new dam break modelling and inundation mapping required? Answer 30: Proponents are to include a scope of services consistent with a Dam Safety Review outlined in section 5.4 of the CDA Dam Safety Guidelines. Question 31: Is inundation mapping a required deliverable for this project? Answer 31: Proponents are to include a scope of services consistent with a Dam Safety Review outlined in section 5.4 of the CDA Dam Safety Guidelines. Question 32: Will the provisional climate change risk assessment be evaluated along with the DSR, or separate from it? Answer 32: Although this scope of work is provisional, it is intended that the climate change risk assessment would be a separate deliverable from the Dam Safety Review. A signed copy of each Addendum must also be included with the bid submission. Failure to include this Addendum may be cause for rejection. If you have any questions, please contact our office by email at procurement@halifaxwater.ca.

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ALL OTHER SPECIFICATIONS, TERMS AND CONDITIONS REMAIN UNCHANGED.

Acknowledgement by Bidder: Company Name: _________________________ Print Name: _____________________________ Signed: ________________________________ Date: __________________________________

End of Addendum #1