Terms of Reference for a Hydro Technical Study of Stephenville

(Blanche Brook and its two tributaries Warm Creek and Cold

Brook)

Water Resources Management Division, Department of Environment and Conservation Government of Newfoundland and Labrador

Revised: August 15th , 2008

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TABLE OF CONTENTS

1. Background..................................................................................................................... 2

2. Objective ......................................................................................................................... 2

3. Study Requirements ........................................................................................................ 4

4. Project Standards .......................................................................................................... 12

5. Administration .............................................................................................................. 13

5.1 Program Administration .......................................................................................... 13 5.2 Hydrotechnical Study Administration ..................................................................... 13 5.3 Study Reports .......................................................................................................... 13 5.4 Financial Consideration........................................................................................... 14

6. Submission of Proposals ............................................................................................... 14

6.1 General Instructions................................................................................................. 14 6.2 Time Frames ............................................................................................................ 15 6.3 Proposal Requirements ............................................................................................ 15 6.4 Evaluation Procedure............................................................................................... 16

7. References..................................................................................................................... 17

APPENDIX A

APPENDIX B

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1. Background The Town of Stephenville has a long history of flooding dating back to 1948. Serious flooding has occurred on several occasions due to ice and debris jams, rain on snow pack events and rainfall alone. The Water Resources Management Division (WRMD) of the Department of Environment and Conservation (hereafter referred to as the department) has carried out two hydrotechnical studies of flooding in Stephenville (1984 and 1996) to prepare flood risk mapping. These studies were entitled “Hydrotechnical Study of Stephenville Area” and “Flood Risk Mapping Study of Stephenville, Kippens and Cold Brook” respectively. Environment Canada carried out an independent study in 1975 entitled “An Evaluation of Flooding in Stephenville”. On September 27, 2005, extensive flooding took place in Stephenville and the surrounding areas. The flood was caused by approximately 151 mm of rainfall concentrated over two days. The flooding moved the stream bed of Blanche Brook as it flows through a marine delta area. Also the stream channel was altered extensively in response to the flood. After the flood to prevent future damage to residential developments, a Flood Control area was established in April 2006 under the Water Resources Act SNL 2002 cW-4.01. The WRMD conducted an investigation to document the locations of flooding, to determine the cause(s) of the flooding, and to compare the extent of the flooding with the flood lines on the 1996 Flood Risk Maps. The 1:100 year hydraulic flood lines were exceeded on Blanche Brook and on Warm Creek. The flood elevation in the residential area off Blanche Street was much higher than expected. This was probably due to a breach of the river bank further upstream. One of the primary conclusions from the preliminary investigation was that the hydrotechnical study and flood risk mapping for Stephenville needs to be updated.

2. Objective This Terms of Reference is for the update of the 1996 hydrotechnical study and flood risk mapping for Stephenville. The sections of the Terms of Reference which follow contain:

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1. The study requirements as determined by the Technical Committee. Hydrotechnical studies are technical in nature and the technical quality of the proposal and the experience of the study team will be the most important criteria in evaluating and selecting a consultant to carry out this study.

2. A description of the study will be administered and how the studies are

conducted.

3. Instructions to consultants Conceptually, a hydrotechnical study and flood risk mapping consists of four major components: hydrology, hydraulics, topographic mapping and public information. The hydrologic component involves the determination of the response of a watershed to major climatic events such as rainstorms, rapid snowmelt or a combination of both. The output from the hydrologic component, in the form of flood flows for specified probabilities, serves as the major input in the hydraulic analysis. This will define the response of the river reaches under consideration to the hydrologic input and other pertinent factors. The output from the hydraulic studies in the form of water surface profiles for the 1:20 and 1:100 year recurrence interval floods, or in some instances a large historic flood, is applied to a detailed topographic map to delineate the extent of flood water levels on the flood plain. The final component involves the development of maps, brochures, and other interpretative information to inform the public, government agencies, private companies, or others of the flood hazard. To ensure that a hydrotechnical study and flood risk mapping is carried out according to prescribed standards, technical guidelines were developed under the Canada- Newfoundland Flood Damage Reduction Program for the hydrologic, hydraulic and topographic mapping components. It is the intent of the WRMD that consultants adhere to the technical guidelines as closely as possible. The guidelines for the Hydrologic and Hydraulic Procedures for Flood Plain Delineation are reproduced herein as Appendix A. It is recognized that in some situations, additional measures may be required.

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3. Study Requirements The purposes of this study are to:

• Update the 1996 Hydrotechnical study for the Town of Stephenville. This will

include updating the three major components of hydrology, hydraulics, and topographic mapping. The study area will consist of Blanche Brook and its two tributaries Warm Creek and Cold Brook. This will not include any work on the fourth component to produce public information.

• Provide updated estimates of the 1:20 and 1:100 year recurrence interval flood levels.

• Provide georeferenced digital map layers for the updated 1:20 year and 1:100 year flood lines.

• Provide updated digitized cross-sections. • Identify possible flood forecasting and warning systems. • Recommend further areas where detailed study will be required.

The consultant hired for this study will make maximum use of all available information, including historical data, related studies carried out by various consultants and government agencies and of the guidelines established. Maximum use should be made of the existing hydrotechnical and other data. The study consists of a thorough review of existing information, the selection of appropriate mathematical models, a detailed evaluation of existing data, the identification of data voids, and the generation of missing data where appropriate, the evaluation of data accuracy, the collection and compilation of new data necessary for the study, the analysis/interpretation of the data, and the derivation of the 1:20 year and 1:100 year recurrence interval flood profiles. More specifically, the Consultant shall:

1. Carry out a thorough review of existing information to obtain an understanding of the flooding problem in the study area and the factors responsible for past floods. Information may be available from some or all of the following:

• Municipal Council files. • Various government departments, including the provincial

Departments of Environment and Conservation, Municipal Affairs, and Works Services and Transportation; and Environment Canada.

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• Newspapers and television/radio stations. • Available aerial photography and mapping. • Water Survey of Canada records.

2. Evaluate the significance of various factors affecting the flooding problem in Stephenville. These factors include but are not limited to:

• Morphology: Rivers and their tributaries have morphological features such as rapids and constrictions which make the area susceptible to ice accumulation and blockages.

• Ice or Debris Jams: the appropriate analyses of river ice systems are

complex and require specialized expertise. The study must address this factor and include it in the determination of the 1:20 and 1:100 design flood profiles.

• Meteorology: It will be necessary to identify and evaluate the in-

fluence of various meteorological factors alone, and in combination, to make a reasonable forecast of the possibility of flooding.

• Physiographic and Cultural Influences: The influence on flooding

of all natural and man made features of this study area should be noted. Factors for consideration may include, but are not limited to: structures across the river, infilling, existing dikes and road bed ele-vations, changes which would affect the flood plain, particularly changes which would affect ice formation and movement, should be identified and their impact evaluated.

• High Flows: Determine the significance of runoff in contributing to

high water levels. It will be the responsibility of the consultant to select appropriate models and model parameters for this study.

The HYMO model was used in a previous study for the Stephenville area. The consultant should evaluate the application of the HEC-HMS model and use it for this study if appropriate. The HYMO input file for the model will be provided to the successful consultant.

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3. Recognizing the significance of the various factors, the limitations in the data base, and other constraints, design a strategy to produce 1:20 and 1:100 year recurrence interval flood profiles for the study area. 4. Select appropriate mathematical model(s) capable of simulating the hydrologic and hydraulic behaviour of the study area. Factors to be considered include:

• The model(s) must take into consideration the level of accuracy prescribed in the

Hydrologic and Hydraulic Procedures for Flood Plain Delineation, attached as Appendix A.

• The technical committee would prefer the use of non proprietary hydrologic and

hydraulic models such as HEC-HMS and HEC-RAS.

• The technical committee would prefer the use of GIS for data input and data output where possible. If appropriate, HEC-GeoRAS should be used for preparation of geometric data for import into HEC-RAS and to process simulation results exported from HEC-RAS.

• All major derivations of model parameters should be thoroughly explained in the

reports for review by the Technical Committee. • All model parameters, their values and method of estimation must be thoroughly

explained in the reports for review by the Technical Committee.

• Consideration should be given to selecting a hydraulic model that can be used later for the evaluation of possible structural changes including channelization, flood control dams, dikes, in stream structures such as bridges/culverts, and flood plain modifications such as improved drainage. The model should also be capable of evaluating the impact on water levels resulting from additional fill in the flood plain. The evaluation of such future changes is not a part of this contract.

• The HYMO and HEC-2 input files for the previous study will be provided to the

successful consultant. 5. Design, co-ordinate and manage a field program for collection of the data and any new information which may be required to:

• Establish the historical flood levels

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• Calibrate and verify the selected mathematical model(s) taking into full con-

sideration the availability and quality of existing data.

The ground surveys should determine the nature and extent of the features which affect the exchange of water between the river and the flood plain. These features should also be photographed. All channel cross-sections for the study should extend to the limits of the mapped flood plain. The consultant must use and relate all survey data to the Geodetic Survey of Canada vertical control datum.

6. The consultants may reuse cross sections data from the previous study in areas where no significant changes have occurred. The consultant should include an allowance to check the accuracy of 10 - 20% of the sections selected for reuse. Some additional field work may be required to locate flood lines on the existing maps or to tie in features that may not be included on the maps. 7. Based on a review of all pertinent data, undertake office studies as are necessary to fill data voids. It will be the responsibility of the consultants to ensure that the hydro- meteorological data provided by other agencies are of acceptable accuracy. 8. The selected model(s) should be calibrated and verified, to the extent possible, using split sample techniques. The consultant must ensure the collection of adequate field data/observation for this purpose. Documentation on recent floods should be used to the extent possible. 9. Carry out a sensitivity analysis of the flood profiles with a view toward identifying overall error. Factors to be considered for the sensitivity analysis should include:

• The hydrologic input,

• Model parameters such as Manning's roughness coefficient, expansion and contraction loss coefficients and channel geometry,

• Assumptions made,

• Any other factor that the consultant may consider appropriate after completion of

field surveys. 10. Produce the 1:20 and the 1:100 flood profiles for the areas and overlay the flood lines on 1:2500 scale digital maps. The 1:20 year and 1:100 year flood lines should be

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digitized as polygons. The georeferenced digital map layers for the updated 1:20 year and 1:100 year flood lines should be provided as ESRI Shape Files and as AutoCAD R2000 DWG Files. All digital files are to be provided in provincial MTM projections (NAD83). Where 1:20 year and 1:100 year flood lines, or other lines, are coincident, the lines should be digitized as the same line and copied to the other appropriate layer(s). This is required as lines may need to be viewed in isolation from other features. Flood zones along rivers should NOT use riverbanks as the edges of polygons. Riverbanks are prone to changes in morphology over time and updates to base mapping can result in significant changes in water features. In such cases the extents / outer edges of flood lines should be digitized then closed across rivers as necessary. Flood zones along shorelines of water bodies and /or coastlines should NOT use these features as the edges of polygons. Shorelines and coastlines are prone to erosion and / or deposition over time and updates to base mapping can result in significant changes in water features. As well, flood zones are often required to be viewed at scales smaller (e.g. 1: 50 000) than the 1:2500 scale mapping used to produce flood risk mapping. Polygons which begin or end at shorelines and coastlines should extend past these features far enough to account for positional changes in features created by changes in the scale of base mapping (i.e. 1:2500 to 1:50 000) that may be used by end users. 1:20 year and 1:100 year flood lines should not be edited to ensure they totally include or exclude buildings or other structures. The positions and shapes of buildings or other structures on digital mapping is not precise enough to make such determinations and is often outdated. In such cases, 1:20 year and 1:100 year flood lines should be drawn through these features until field visits can be made in order to determine the threat of flooding posed to these structures. See the figure below:

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The feature codes attached as Appendix B should be used. Specific instructions for the ESRI Shape Files and as AutoCAD R2000 DWG Files are as follows:

• ESRI Shape Files

o Polygons on separate layers for each of the following flood areas: 1:20 year, 1:100 year, historical, ice or debris, flood control, and special policy.

o Polygons on a separate layer for the contributing drainage area

(watershed). The area is to be delineated by the contractor based on data in the hydrotechnical study (available upon request) for a given area.

o Cross Section Lines on separate layer with the following attribute

information – cross section number, 1:20 and 1:100 year elevations. o Base map information is required as a separate layer.

o Projection files to be included

• AutoCAD R2000 DWG Files

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o Polygons on separate layers for each of the following flood areas: 1:20 year, 1:100 year, historical, ice or debris, flood control, and special policy.

o Cross Section Lines on separate layer with the following attribute

information – cross section number, 1:20 and 1:100 year elevations.

o Base map information is required as a separate layer.

11. Provide an accurate digital delineation of the watershed contributing to the flood flows. The georeferenced digital flood watershed map should be provided as an ESRI Shape files. A digital inventory of land use and land cover in the flood watershed should be provided. If possible, remote sensing should be used to compile the land cover inventory. The procedure should be documented so that the WRMD could use this to update the land cover inventory in future years.

12. Provide monthly progress reports and discuss the various aspects of the investigation with the Technical Committee, as required or requested. 13. Develop a work schedule and description of work output such that study milestones and associated outputs may be monitored for both time and costs. Updates are to be provided with monthly progress reports. 14. The consultant must include all anticipated expenditures in the estimate and provide assurance that no extra funds will be expended before obtaining approval for the extra work. 15. Provide two drafts of the final report. For the first draft, the consultant should submit the report chapter by chapter as each chapter is completed. The second report shall be submitted after all chapters have been reviewed by the Technical Committee. Four copies of each are required. 16. Provide on DVD all input and output files for all computer models used in the study. All documentation required to operate the models must also be provided. 17. Provide, where practical, all technical drawings and graphics on CD in AutoCAD and ESRI Shape file formats.

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18. Provide 10 printed copies of the final report and 10 copies of the technical appendices. The text of the final report must also be provided on CD in Microsoft Word and Adobe PDF format.

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4. Project Standards To ensure that flood risk mapping is carried out to appropriate technical standards that are uniform across the country, technical guidelines were developed for the FDR Program. It is intended that the Consultant adhere to these technical guidelines as closely as possible. The guidelines, Hydrologic and Hydraulic Procedures for Flood Plain Delineation, are reproduced in Appendix A. Within the study area, river cross-sections should be extended across the flood plain. The end points of all cross sections should be described and the positions of all cross sections plotted on available maps. In the final report or its appendices, the Consultant shall present carefully drawn and well identified cross-sections obtained for the study. Also, appropriate tables of elevations versus distance of all section points used in the model(s) should be provided, either in the report or in digital form on CD. Any hydrometric and stage data used by the Consultant shall be of suitable accuracy and reliability to meet the needs of this study. Liaison should be maintained with Water Survey of Canada regarding the use of data obtained by them at the hydrometric stations and the collection of hydrometric data by the consultant. The consultant must obtain data in the most up-to-date form available from the various agencies. It is also the responsibility of the consultant to ensure that the data is checked, verified and updated by the agencies. Further review and analysis should be done by the Consultant to detect any errors or determine any necessary adjustments to the data. In the final report or its appendices, references should be provided for all published data used in the study. Also, any data derived for the study must be presented. The methods and conditions under which the data were collected and used should be discussed. A discussion of the sensitivity of the flood profiles to the data should be presented. All assumptions and calculations of parameters must be presented with reasonable justification in the text. All field surveys and data compilation should be carried out when possible, using metric units of measurement. In the final report and its appendices, all data, equations, calcula-tions and results shall be given using the International System of Units (SI) and presented using the Canadian standards for writing SI units and numbers. All converted data shall be identified with a note giving the appropriate conversion factors. All cross-section, measured water data and simulated water surface profiles shall be related to geodetic datum.

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5. Administration

5.1 Program Administration The Manager of the Hydrologic Modelling Section will be the Project Engineer. The Manager shall be assisted by a Technical Committee consisting of members from the WRMD. Additional members may be added to the Technical Committee if required. The Technical Committee will be responsible for the technical supervision of the hydrotechnical study.

5.2 Hydrotechnical Study Administration The Consultant will report to the Project Engineer regularly and maintain liaison with the Project Engineer on all aspects of the study. If needed, the Consultant will be required to attend meetings with the Technical Committee to discuss the technical aspects of the study. Normally, the meetings are held at provincial government offices in St. John's. The Consultant must provide monthly progress reports to the Project Engineer. Any difficulties and project delays must be reported as and when they are recognized or foreseen. Clarification may be requested by the Project Engineer on any item in the progress report. The Consultant will be expected to respond to any reasonable request of the Project Engineer in a thorough and diligent manner. The Consultant shall develop a work schedule such that study milestones and associated outputs may be monitored. Updates are to be provided with progress reports. Any deviation in the methodology, scope or assigned staff for the study described in the Consultant's proposal must be reviewed and approved by the Technical Committee. Also, the Technical Committee will be available to provide, when possible, technical advice and reasonable assistance to the Consultant.

5.3 Study Reports Ten copies of the final report shall be prepared. A separate report shall be prepared containing all field data, photographs, and computer simulations done in support of the

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study but not included in the final report. Ten copies of this report will be required. The consultant must make a realistic estimate of the printing cost for the final report based on the anticipated number of pages. No claim for extra printing costs will be accepted. In addition, the text of the final report must be provided on CD in Microsoft Word format and the technical drawings and graphics must be provided on CD in AutoCAD compatible format.

5.4 Financial Consideration An itemized project budget shall be submitted by the Consultant with the proposal. The Consultant shall keep proper records of the work performed and expenses incurred during the study. The Consultant shall submit invoices for amounts payable to the Consultant, subject to a work schedule and description of work output, as required by the terms of a formal contract with the department. Progress reports, that relate progress to the work program and output schedule, shall be submitted with the invoices.

6. Submission of Proposals

6.1 General Instructions SIX (6) copies of the proposal should be submitted to:

Director Water Resources Management Division Department of Environment and Conservation, 4th Floor, Confederation Building West Block, St. John's NL A1B 4J6

Proposals will be received up to and until 3:00 pm local time, September 05, 2008.

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6.2 Time Frames There is a tight timeframe for the completion of this project. The following dates are given;

Request for Proposals Issue Date: August 18, 2008 Submission Deadline Date: September 5, 2008 Contract Award Date: September 19, 2008 Consulting Services Start Date: September 22, 2008 Contract Completion Date: March 15, 2009 Submission of Invoices Deadline Date: March 25, 2009

6.3 Proposal Requirements The consultant's proposal should include: Proposed Methodology: The format and contents of the proposal must provide

sufficient detail so that technical evaluation of the proposal can be made. The proposed methodology must be properly presented to provide a clear picture of the level of effort and appropriateness of the methodology. The cost estimates should reflect the level of effort.

Organization Chart: The chart should indicate the names of the individuals to be

involved in the study and the lines of responsibility. Estimated Project Budget: The budget should identify expected expenditures

on project administration and expenses, physical surveys, event monitoring, hydrologic investigations, hydraulic investigations, flood line plotting and draft and final report preparation and report printing.

Work Schedule: The work schedule should indicate the start and completion

date for the project as well as for individual study components. Study Personnel: A curriculum vitae for each of the study personnel should be

included. The proposal should also indicate the time to be spent on the project by the key study personnel.

Proprietary Model(s): The Technical Committee prefers the use of

non-proprietary models such as HEC-HMS and HEC-RAS.

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6.4 Evaluation Procedure In evaluating proposals the Technical Committee will consider the following: Strategy: The consultant should demonstrate a comprehensive knowledge of the

flooding problems and the major causative factors. A sound appreciation of the aspects which may be of secondary importance should also be demonstrated.

Specific information is required to assess and rank each proposal. This

may include, for example, the type(s) of model(s) which apply, and how each is applied. For field work the consultant should specify the amount of work anticipated. For example, the number of cross sections to be surveyed should be indicated for each area.

Knowledge and Experience: The consultant should demonstrate good

administrative and technical skills, and show at both the project management and technical levels an adequate expertise and compe-tence to meet the requirements of the study. The demonstrated expertise of the study team is critically important for the successful completion of the study.

Cost: Costs should be itemized by task and include all the work required to

carry out the study as specified in the Terms of Reference. The cost of the proposal will be the deciding factor only when the two or more proposals are technically acceptable and are of comparable standard as evaluated by the Technical Committee.

It is imperative that the consultant should provide the details of any additional costs anticipated because of uncertainties, inadequate information at the time of submission of the proposal, or any other reason, to assist the Technical Committee in the evaluation of the proposal.

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7. References An Evaluation of Flooding in Stephenville, Newfoundland, Water Planning and Management Branch, Inland waters Directorate, Atlantic Region, Halifax, Nova Scotia, December 1975. Hydrotechnical Study of the Stephenville Area, Main Report, Volume 1 of 2, Nolan Davis and Associates Limited with Cumming-Cockburn and Associates Limited, prepared for the Department of Environment, February 8, 1984. Hydrotechnical Study of the Stephenville Area, Appendices, Volume 2 of 2, Nolan Davis and Associates Limited with Cumming-Cockburn and Associates Limited, prepared for the Department of Environment, February 8, 1984. Flood Risk Mapping Study of Stephenville, Kippens and Cold Brook, Main Report, Sheppard Green Engineering and Associates Limited, prepared for the Department of Environment, May, 1996. Flood Risk Mapping Study of Stephenville, Kippens and Cold Brook, Technical Appendices, Sheppard Green Engineering and Associates Limited, prepared for the Department of Environment, May, 1996. These references are available at http://www.env.gov.nl.ca/wrmd/TOR_Studies.htm

APPENDIX A

HYDROLOGIC AND HYDRAULIC PROCEDURES

FOR

FLOOD PLAIN DELINEATION

APPENDIX B

FEATURE CODES - FLOOD RISK MAPPING

Feature Codes - Flood Risk Mapping

DeptData Type Status Feature Description FCODE Feature Type

Fill Colour Fill Type

Border Colour

Border Type

EN FR DS - Designated FF - Floodway FringeDesignated Floodway Fringe - 1:100 year return interval flood zone. Some types of development are permitted with flood proofing.

ENFRDSFF Area Yellow Trans 50% Black Solid

CS - Cross Section

Surveyed cross section used in hydraulic model to develop flood lines - attributes: 1:20 year flood elevation, 1:100 year elevation and cross section number to be included

ENFRDSCS Line Magenta Solid Magenta Solid

FW - FloodwayDesignated Floodway - 1:20 year return interval flood zone. Most types of development, particularly residential, are not permitted.

ENFRDSFW Area Orange Trans 50% Black Solid

SP - Special PolicySpecial Policy Area Floodway - Some development may be permitted with an approved comprehensive development plan for the area.

ENFRDSSP Area Pink Trans 50% Black Solid

HS - Historical Historical Flood Extent - Delineation of recorded extreme flood event ENFRDSHS Area Light

Green Trans 50% Black Solid

IB - Ice or Debris FloodIce or Debris Flood - Delineation of recorded or estimated flood event with ice or debris blockages

ENFRDSIB Area Light Green Trans 50% Black Dashed

SE - Study Extents Flood Study Extents - Delineation of flood risk mapping study limits ENFRDSSE Line Gray Solid Gray Solid

UD - Undesignated FF - Floodway FringeDesignated Floodway Fringe - 1:100 year return interval flood zone. Some types of development are permitted with flood proofing

ENFRUDFF Area Orange Trans 25% Black Solid

FW - Floodway

Interim (Under Review) Designated Floodway - 1:20 year return interval flood zone. Most types of development, particularly residential, may not be permitted.

ENFRUDFW Area Yellow Trans 25% Black Solid

HS - Historical Historical Flood Extent - Delineation of recorded extreme flood event ENFRUDHS Area Pink Trans 25% Black Solid

IB - Ice or Debris FloodIce or Debris Flood - Delineation of recorded or estimated flood event with ice or debris blockages

ENFRUDIB Area Light Green Trans 25% Black Solid

FC - Flood Control FC - Flood Control AreaFlood Control Area - Development may be restricted to ensure that the use of these areas is compatible with the flood hazard.

ENFRFCFC Area Red Trans 50% Black Solid

DT - Total Drainage Area Total Drainage area at downstream limit of flood risk area ENFRFDDT Area Cyan Solid Cyan Solid

Department of Environment and Conservation

Water Resources Management Division

FD - Flood Drainage

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Feature Codes - Flood Risk Mapping

DeptData Type Status Feature Description FCODE Feature Type

Fill Colour Fill Type

Border Colour

Border Type

Department of Environment and Conservation

Water Resources Management Division

DS - Sub basin drainage area DS - Sub basin drainage area, generally multiple areas as defined in the hydrotechnical study ENFRFDDS Area Cyan Trans 50% Cyan Solid

FD - Flood Drainage

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