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HomeMy WebLinkAboutCAG1993-017 - Original - Mill Creek/Garrison Creek - Hydrologic & Hydraulic Analysis CONSULTANT SERVICES CONTRACT BETWEEN THE CITY OF RENT AND R.W. BECK AND ASSOCIATES THIS AGREEMENT is made by and between the City of Kent, a Washington municipal corporation (hereinafter the "City") , and R.W. Beck and Associates, a general partnership organized under the laws of the State of Washington, located and doing business at 2101 Fourth Avenue, Suite 600, Seattle, Washington 98121 (hereinafter the "Consultant") . Recitals 1. The City is presently engaged in the "Mill Creek/Garrison Creek Hydrologic and Hydraulic Analysis" and desires that the Consultant perform services necessary to provide consultation and advice to the City on the preparation of plans, specifications, and cost estimates for the "Mill Creek/Garrison Creek Hydrologic and Hydraulic Analysis. " 2 . The Consultant agrees to perform the services more specifically described in the Scope of Work, dated August 2, , 1993 , including any addenda thereto as of the effective date of this agreement, attached hereto as Exhibit A which is incorporated herein by this reference as if fully set forth. NOW, THEREFORE, in consideration of the mutual promises set forth herein, it is agreed by and between the parties as follows: I. Description of Work Consultant shall perform all work as described in Exhibit A. R.W. BECK CONSULT K--Page 1 of 14 Rev. 09/20/93 II. Payment A. The City shall pay the Consultant an amount based on time and materials, an amount not to exceed $196,122.00 for the services described in Section I herein. This is the maximum amount to be paid under this Agreement for Tasks I- 1. 13 in Exhibit A, and shall not be exceeded without the prior written authorization of the City in the* form of a negotiated and executed supplemental agreement. PROVIDED, HOWEVER, the City reserves the right to establish priorities and milestones for the Consultant ' s compensated services under the time frame set forth in Section IV herein before , reaching the maximum amount. The Consultant' s compensation shall be set forth in Exhibit B. B.. The Consultant shall submit monthly payment invoices to the City after such services have been performed, and a final bill upon completion of all the services described in this Agreement. The City shall pay the full amount of an invoice within forty-five (45) days of receipt. If the City objects to all or any portion of any invoice, it shall so notify the Consultant of the same within fifteen (15) days from the date of receipt and shall pay that portion of the invoice not in dispute, and the parties shall immediately make every effort to settle the disputed portion. C. In the event the Scope of Work is modified or changed so that more or less work or time is required by the Consultant, and such modification is reached by mutual agreement of the parties to this contract, the payment for services and maximum contract amount R.Y. BECK CONSULT K--Page 2 of 14 Rev. 09/20/93 r shall be adjusted accordingly upon agreement of the parties. III. Relationship of Parties The parties intend that an independent contractor-employer relationship will be created by this Agreement. As Consultant is customarily engaged in an independently established trade which encompasses the specific service provided to the City hereunder, no agent, employee, representative or sub-contractor of Consultant shall be or shall be deemed to be the employee, agent, representative or sub-contractor of the City. In the performance of the work, Consultant is an independent contractor with the ability to control and direct the performance and details of the work, the City being interested only in the results obtained under this Agreement. None of the benefits provided by the City to its employees, including, but not limited to, compensation, insurance, and unemployment insurance are available from the City to the employees, agents, representatives, or sub-contractor of the Consultant. Consultant will be solely and entirely responsible for its acts and for the acts of Consultant's agents, employees, representatives and sub-contractors during the performance of this Agreement. The City may, during the term of this Agreement, engage other independent contractors to perform the same or similar work that Consultant performs hereunder. IV. Duration of Work The City and Consultant agree that work will begin on the tasks described in Exhibit A immediately upon execution of this Agreement. The parties agree that the work described in Exhibit A is to be completed within 220 calendar days of the execution of this Agreement; provided however, that additional time shall be R.Y. BECK CONSULT K--Page 3 of 14 Rev. 09/20/93 granted by the City for excusable delays or extra work, as described in Section VI. (D) below. V. Place of Work The Consultant shall perform the work authorized under this Agreement at its offices in Seattle, Washington. Meetings with the City staff as described in Exhibit A, Scope of Work, shall take place at the City's offices at 400 West Gowe, Kent, Washington, or at locations mutually agreed upon by the parties. VI. Termination A. Termination of Agreement If the City receives reimbursement by any federal, state, or other source for work described in Section I herein, and that funding is withdrawn, reduced or limited in any way, or the project is cancelled or substantially reduced after the execution date of this Agreement and prior to the completion of the work hereunder, the City may summarily terminate this Agreement. Termination shall be effective ten calendar days after Consultant's receipt of the written notice by certified mail. B. Termination for Failure to Provide Services Bargained For. The Consultant agrees that it was hired by the City based on the Consultant' s representation that employees identified in the Scope of Work, attached hereto as Exhibit A, will be available to perform the services described in Section I for the duration of this Agreement. If any of the employees identified in the Scope of Work are unavailable to perform the services bargained for, for any reason, the City of Kent reserves R.Y. BECK CONSULT K--Page 4 of 14 Rev. 09/20/93 the right to terminate this contract or renegotiate the amount of consideration. The consultant must immediately notify the City, in writing, if any employee identified in the Scope of Work is unavailable to perform the services described in Section I of this Agreement. Nothing in the foregoing language will alter the Consultant's independent contractor status. C. Termination for Failure to Prosecute Work or to Complete Work Satisfactorily If the Consultant refuses or fails to prosecute the work with such diligence as will ensure its completion within the time frames specified herein, or as modified or extended as provided in this Agreement, or to complete such work in a manner satisfactory to the City, then the City may, by written notice to the Consultant, give notice of its intention to terminate the Consultant's right to proceed with the work. On such notice, the Consultant shall have ten (10) calendar days to cure, to the satisfaction of the City or its representative, or the City shall send the Consultant a written termination letter which shall be effective upon the Consultant's receipt of the written notice by certified mail. Upon termination, the City may take over the work and prosecute the same to completion, by contract or otherwise, and Consultant shall be liable to the City for any additional costs incurred by it in the completion of the Scope of Work referenced as Exhibit A and as modified or amended prior to termination. "Additional Costs" shall mean all reasonable costs incurred by the City beyond the maximum contract price specified in II (A) , above. R.W. BECK (CONSULT K--Page 5 of 14 Rev. 09/20/93 D. Excusable Delays The right of Consultant to proceed shall not be terminated nor shall Consultant be charged with liquidated damages for any delays in the completion of the work due to: 1) any acts of the federal government in controlling, restricting, or requisitioning materials, equipment, tools, or labor by reason of war, national defense, or other national emergency; 2) any acts of the City, its consultants, or other public agencies causing such delay; and 3) causes not reasonably foreseeable by the parties at the time of the execution of the Agreement that are beyond the control and without the fault or negligence of the Consultant, including, but not restricted to, acts of God, fires, floods, strikes, or weather of unusual severity; and (4) negotiated and executed supplemental agreements between the City and Consultant for Consultant to perform extra work defined as tasks not included in the Scope of Work referenced as Exhibit A. PROVIDED, HOWEVER, that the Consultant must promptly notify the City within ten (10) calendar days in writing of the cause of the delay. If, on the basis of the facts and the terms of this Agreement, the delay is properly excusable, the City shall, in writing, extend the time for completing the work for a period of time commensurate with the period of excusable delay. E. Rights Upon Termination In the event of termination, the City shall pay for all services performed by the Consultant to the effective date of termination, as described on a final invoice submitted to the City. After termination, the City may take possession of all records and data within the Consultant's possession pertaining to this project which R.Y. BECK CONSULT K--Page 6 of 14 Rev. 09/20/93 may be used by the City without restriction. Any such use not related to the project which Consultant was contracted to perform shall be without liability or legal exposure to the Consultant. VII. Discrimination In the hiring of employees for the performance of work under this Agreement or any sub-contract hereunder, the Consultant, its sub- contractors, or any person acting on behalf of such Consultant or sub-contractor shall not, by reason of race, religion, color, sex, national origin, or the presence of any sensory, mental, or physical disability, discriminate against any person who is qualified and available to perform the work to which the employment relates. VIII. Indemnification Consultant shall defend, indemnify and hold the City, its officers, officials, employees, agents and volunteers harmless from any and all claims, injuries, damages, losses or suits, including all legal costs and attorney fees, arising out of or in connection with the performance of this Agreement, but Consultant's liability hereunder shall be only to the extent of the negligence or comparative fault incurred by Consultant, its subconsultants, agents or assigns. The City's inspection or acceptance of any of Consultant's work when completed shall not be grounds to avoid any of these covenants of indemnification. IT IS FURTHER SPECIFICALLY AND EXPRESSLY UNDERSTOOD THAT THE INDEMNIFICATION PROVIDED HEREIN CONSTITUTES THE CONSULTANT'S WAIVER OF IMMUNITY UNDER INDUSTRIAL INSURANCE, TITLE 51 RCW, SOLELY FOR THE PURPOSES OF THIS INDEMNIFICATION. THE PARTIES FURTHER ACKNOWLEDGE THAT THEY HAVE MUTUALLY NEGOTIATED THIS WAIVER. THIS R.W. BECK CONSULT K--Page 7 of 14 Rev. 09/20/93 WAIVER SHALL NOT INCLUDE CONSULTANT'S IMMUNITY AS A DESIGN PROFESSIONAL GRANTED UNDER RCW 51.24 . 035. The provisions of this section shall survive the expiration or termination of this Agreement. I%. Insurance The Consultant shall procure and maintain for the duration of the Agreement, insurance against claims for injuries to persons or damage to property which may arise from or in connection with the performance of the work hereunder by the Consultant, its agents, representatives, employees, sub-consultants or sub-contractors. Before beginning work on the project described in this Agreement, the Consultant shall provide a Certificate of Insurance evidencing: 1. Automobile Liability insurance with limits no less than $1, 000, 000 combined single limit per accident for bodily injury and property damage; and 2 . Commercial General Liability insurance written on an occurrence basis with limits no less than $1, 000, 000 combined single limit per occurrence and $2,000, 000 aggregate for personal injury, bodily injury and property damage. Coverage shall include but not be limited to: blanket contractual; products/completed operations/broad form property damage; explosion, collapse and underground (XCU) if applicable; and employer's liability; and 3 . Professional Liability insurance with limits no less than $1,000, 000 limit per occurrence. Any payment of deductible or self insured retention shall be the sole responsibility of the Consultant. R.Y. BECK CONSULT K--Page 8 of 14 Rev. 09/20/93 The City shall be named as an additional insured on the Commercial General Liability insurance policy, as respects work performed by or on behalf of the Consultant and a copy of the endorsement naming the City as additional insured shall be attached to the Certificate of Insurance. The City reserves the right to receive a certified copy of all the required insurance policies. The Consultant's Commercial General Liability insurance shall contain a clause stating that coverage shall apply separately to each insured against whom claim is made or suit is brought, except with respects to the limits of the insurer's liability. The Consultant's insurance shall be primary insurance as respects the City and the City shall be given thirty (30) days prior written notice by certified mail, return receipt requested, of any cancellation, suspension or material change in coverage. X. Exchange of Information The City warrants the accuracy of any information supplied by it to Consultant for the purpose of completion of the work under this Agreement. The parties agree that the Consultant will notify the City of any inaccuracies in the information provided by the City as may be discovered in the process of performing the work, and that the .City is entitled to rely upon any information supplied by the Consultant which results as a product of this Agreement. XI. Ownership and Use of Records and Documents Original documents, drawings, designs and reports developed under this Agreement shall belong to and become the property of the City upon payment in full, as determined solely by the City. All written information submitted by the City to the Consultant in connection with the services performed by the Consultant under this Agreement will be safeguarded by the Consultant to at least the R.W. BECK CONSULT K--Page 9 of 14 Rev. 09/20/93 same extent as the Consultant safeguards like information relating to its own business. If such information is publicly available or is already in Consultant's possession or known to it, or is rightfully obtained by the Consultant from third parties, Consultant shall bear no responsibility for its disclosure, inadvertent or otherwise. All data, documents and files created by Consultant under this Agreement may be stored at Consultant's office in Seattle, Washington. Consultant shall make such date, documents, and files available to the City upon its request at all reasonable times for the purpose of editing, modifying and updating as necessary until such time as the City is capable of storing such information in the City's offices. Duplicate copies of this information shall be provided to the City upon its request, and at reasonable cost. Any use or reuse of the documents, data and files created by Consultant for the City on this project by anyone other than Consultant on any other project shall be without liability or legal exposure to Consultant. XII. Recyclable Materials Pursuant to City of Kent Ordinance No. 3066, The City of Kent requires its contractors and consultants to use recycled and recyclable products whenever practicable. A price preference may be available for any designated recycled product. XIII. City's Right of Inspection Even though Consultant is an independent contractor with the authority to control and direct the performance and details of the work authorized under this Agreement, the work must meet the approval of the City and shall be subject to the City' s general right of inspection to secure the satisfactory completion thereof. R.Y. BECK CONSULT K--Page 10 of 14 Rev. 09/20/93 The Consultant agrees to comply with all federal, state, and municipal laws, rules, and regulations that are now effective or in the future become applicable to Consultant's business, equipment, and personnel engaged in operations covered by this Agreement or accruing out of the performance of such operations. XIV. Consultant to Maintain Records to Support Independent Contractor Status On the effective date of this Agreement (or shortly thereafter) , Consultant shall: A. File a schedule of expenses with the Internal Revenue Service for the type of business Consultant conducts; B. Establish an account with the Washington State Department of Revenue and other necessary state agencies for the payment of all state taxes normally paid by employers, register to receive a unified business identifier number from the State of Washington; and C. Maintain a separate set of books and records that reflect all items of income and expenses of Consultant's business, all as described in the Revised Code of Washington (RCW) Section 51. 08. 195, as required to show that the services performed by Consultant under this Agreement shall not give rise to an employer-employee relationship between the parties which is subject to RCW Title 51, Industrial Insurance. XV. Work Performed at Consultant's Risk Consultant shall take all precautions necessary and shall be responsible for the safety of its employees, agents, and subcontractors in the performance of the work hereunder and shall utilize all protection necessary for that purpose. All work shall be done at Consultant's own risk, and Consultant shall be R.Y. BECK CONSULT K--Page 11 of 14 Rev. 09/20/93 responsible for any loss of or damage to materials, tools, or other articles used or held for use in connection with the work. XVI. Non-Waiver of Breach The failure of the City to insist upon strict performance of any of the covenants and agreements contained herein, or to exercise any option herein conferred in one or more instances shall not be construed to be a waiver or relinquishment of said covenants, agreements, or options, and the same shall be and remain in full force and effect. XVII. Resolution of Disputes and Governing Law Should any dispute, misunderstanding, or conflict arise as to the terms and conditions contained in this Agreement, the matter shall first be referred to the City, and the City shall determine the term or provision's true intent or meaning. The City shall also decide all questions which may arise between the parties relative to the actual services provided or to the sufficiency of the performance hereunder. If any dispute arises between the City and Consultant under any of the provisions of this Agreement which cannot be resolved by the City' s determination in a reasonable time, or if Consultant does not agree with the City's decision on the disputed matter, jurisdiction of any resulting litigation shall be filed in King County Superior Court, King County, Washington. This Agreement shall be governed by and construed in accordance with the laws of the State of Washington. Each party shall be solely responsible for its costs, expenses and reasonable attorney's fees incurred in any litigation arising out of the enforcement of this Agreement. Rev. �/� R.Y. BECK CONSULT K--Page 12 of 14 XVIII. Written Notice All communications regarding this Agreement shall be sent to the parties at the addresses listed on the signature page of the agreement, unless notified to the contrary. Any written notice hereunder shall become effective upon the date of mailing by registered or certified mail, and shall be deemed sufficiently given if sent to the addressee at the address stated in this Agreement or such other address as may be hereafter specified in writing. XIX. Assignment Any assignment of this Agreement by the Consultant without the written consent of the City shall be void. If the City shall give its consent to any assignment, this paragraph shall continue in full force and effect and no further assignment shall be made without the City's consent. XX. Modification No waiver, alteration, or modification of any of the provisions of this Agreement shall be binding unless in writing and signed by a duly authorized representative of the City and Consultant. XXI. Entire Agreement The written provisions and terms of this Agreement, together with any Exhibits attached hereto, shall supersede all prior verbal statements of any officer or other representative of the City, and such statements shall not be effective or be construed as entering into or forming a part of or altering in any manner whatsoever, this Agreement or the Agreement documents. The entire agreement between the parties with respect to the subject matter hereunder is contained in this Agreement and any Exhibits attached R.Y. BECK CONSULT K--Page 13 of 14 Rev. 09/20/93 hereto, which may or may not have been executed prior to the execution of this Agreement. All of the above documents are hereby made a part of this Agreement and form the Agreement document as fully as if the same were set forth herein. However, should any language in any of the Exhibits to this Agreement conflict with any language contained in this 14-page Agreement, this Agreement shall prevail. IN WITNESS WHEREOF, the parties have executed this Agreement on this 1.2- day of 1993 . R.W. PECK AND ASSOCIATES THE CITY OF KENT BY: - BY: "Ai7l I s Princ' al Director of Public Works BY: Mayor Notices to be sent to: R.W. Egcjc and ociates Mr. Don Wickstrom, P.E. ATTN• - Director of Public Works 2101•Fourth Avenue, Suite 600 City of Kent Seattle, Washington 98121 220 Fourth Avenue South Kent, Washington 98032 APPROVED AS TO FORM: Kent'yCity Attorney N", 4 ATTEST: �.J Kent City C1 k RYBECKCK.plrk R.Y. BECK CONSULT K--Page 14 of 14 Rev. 09/20/93 EMJIBIT A SCOPE OF WORK CITY OF KENT MILL CREEK STORMWATER MANAGEMENT ANALYSIS PHASE 1 - FIELD INVENTORY/ALTERNATIVE SOLUTION IDENTIFICATION Task 1.1 Review Existing Data A review will be made of the City's available plans, maps, and data that may impact the surface water in the study area. The City shall collect and provide to the Consultant the items identified below: • Results of prior and current environmental studies • Utility maps • Historical flooding problem data • Topographic maps • Assessors maps ' • Gaging information • Other relevant studies • GIS drawings • Base Map from December 1989 HEC-2 study • Report by Parametrix on erosion problems in Mill Creek Canyon • Details of slope stabilizing work performed by Kennedy-Jenks Task 1.2 Field Inventory and Residents Survey 1.2.1 Mill Creek The Consultant shall conduct a field inventory of the existing culverts, bridges, any visually-apparent changes in channel section or slope, and pertinent floodplain features along Mill Creek from its mouth to Earthworks Park and between the upstream end of Mill Creek Canyon and the Upper Mill Creek Detention Pond. The Consultant shall use the inventory and available survey information frorn the City to prepare a list of structures and cross- sections that need to be surveyed. Since no current computer model exists for the portion of Mill Creek between 76th Avenue S to Highway 167, all the channel structures and representative channel sections will need to be surveyed in this section. The HEC-2 model developed by CH2M Hill for a 1985-87 Flood Insurance Study for the section of Mill Creek from 76th Avenue S to Earthworks Park will be used to the extent possible. The City shall provide the necessary field surveys. Although the existing HEC-2 models are moderately recent, some changes are likely to have occurred within the stream corridor, which would affect the performance of the model. Detailed review of the existing models and comparison with the field inventories and other recent data will be undertaken by the Consultant. This will help determine the new survey needs and allow an updated model to be developed. R.W. Bcck and Associates 08/02/93 BCCCW WO.881 The Consultant shall conduct a survey asking streamside businesses, residents and City personnel about water levels during major flood events. As part of this survey, the Consultant shall attempt to gather water level information during the December 1989, January 1990, November 1990, and April 1991 storm events. Information on observed high water levels will be flagged for the City to determine the corresponding elevations as part of the field survey work. This information will be used in conjunction with the hydraulic model to calibrate the hydrologic model described in Task 1.5.1. In view of the extreme importance of accurate survey information for the Kent Lagoons Project, surveys will also include additional cross-sections to be specified by the Consultant to be used to check and verify the surveys in previous studies. Location and extent of new surveys will be outlined for the City of Kent survey crews on the GIS maps provided by the City. 1.2.2 Springbrook Creek The Consultant shall conduct a field inventory of Springbrook Creek as was done in Task 1.2.1 for Mill Creek. The Consultant shall note existing culverts, bridges, any visually apparent changes in channel section or slope, and pertinent floodplain features along Springbrook Creek from its confluence with Mill Creek to the upstream side of SR 167. The Consultant shall use the inventory and available survey information frorn the City to prepare a list of structures and cross-sections that need to be surveyed. The City shall provide the necessary field survey. The Consultant shall conduct a survey asking streamside businesses, residents and City personnel about water levels during major flood events. As part of this survey, the Consultant shall attempt to gather water level information during the December 198p, January 1990, November 1990, and April 1991 storm events. Information on observed high water levels will be flagged for the City to determine the corresponding elevations as part of the field survey work. This information will be used in conjunction with the hydraulic model to calibrate the hydrologic model described in Task 1.5.2. Task 1.3 Design Criteria The Consultant, in conjunction with the City, shall define the base flood design criteria to be used in this analysis. It is understood that the City currently designs for a 25-year storm event. It may be advantageous to try to design for a 100-year event, as this is becoming more of a standard in the state of Washington. The Consultant shall evaluate this criteria and recommend design criteria to be used in this analysis. Task 1.4 Hydraulic Analysis and Problem Identification 1.4.1 Mill Creek The existing HEC-2 models will be updated by the Consultant to represent current channel and floodplain conditions. This will include the addition of new cross-sections and structural crossings and the modification of existing ones. Furthermore, existing culvert input to the models will be modified to reflect the new HEC-2 culvert methods, which were BCCCWW0.881 2 R.W. Bcck and Associates 08/02/93 unavailable at the time of the previous studies. Culverts at that time had to be approximated as bridges. The current release of HEC-2, however, includes direct methods for analyzing culverts, which are both more accurate and intuitively more simple. The final result of these modifications and additions will be one continuous HEC-2 model of current conditions, from Springbrook Creek to Earthworks Park and an HEC-2 model between the upper end of Mill Creek Canyon and the Upper Mill Creek Detention Pond. See Figure 1 for the extent of the HEC-2 models. The water level information gathered in Task 1.2.1 for the four major recent flood events will be used with the HEC-2 model to estimate peak flows during these events. The peak flows will be used to calibrate the HSPF model in Task 1.5.1. The Consultant shall use the HEC-2 analysis and interviews with City staff and the public to identify and compile a master list of existing and future drainage problems along Mill Creek. It is possible that the Consultant may need to extend the Full Equations (FEQ) unsteady flow model of Springbrook Creek developed by the Consultant for the City of Renton to include more of the area upstream of the confluence of Springbrook with Mill Creek. The purpose of extending the model around the confluence would be to analyze for a possible flow reversal in the channels. An evaluation of the completed HEC-2 models for both Mill and Springbrook Creeks will determine the need for extending the FEQ model above the confluence. If it appears from the HEC-2 models that the flow reversals could occur, a decision to extend the FEQ model would be made at that time. Including the FEQ work would then require an amendment to this scope of work and budget. A master list of existing and future drainage problems shall be compiled based on the HEC-2 analysis and interviews with City staff and.the public. 1.4.2 SDrinQbrook Creels The existing HEC-2 model of Springbrook Creek from its confluence with Mill Creek to SR 167 will be updated by the Consultant to represent current channel and floodplain conditions. The model will also include the portion of Upper Springbrook Creek from its confluence with Springbrook to the upstream side of SR 167. This will include the addition of new cross-sections and structural crossings and the modification of existing ones. The result shall be a continuous backwater model of Springbrook Creek from its confluence with Mill Creek to the upstream side of SR 167. See Figure 1 for the extent of the HEC-2 model. The water level information gathered in Task 1.2.2 for the four major recent flood events will be used with the HEC-2 model to estimate peak flows during these events. The peak flows will be used to calibrate the HSPF model in Task 1.5.2. The Consultant shall use the HEC-2 analysis and interviews with City Staff and the public to identify and compile a master list of existing and future drainage problems along Springbrook Creek. L3CCCWW0.881 3 R. W. Bcck and Associates 08/02/93 Task 1.5 Hydrology 1.5.1 Mill Creek Past work on Mill Creek will be reviewed. The existing models will be checked, and routing of flows through Kent Lagoons facility will also be reviewed. Familiarization and review of the new stormwater quantity control standards for Kent will also be undertaken. Existing HSPF models for Mill Creek will be updated by the Consultant to reflect major changes in the current land uses and any changes to the projected future land use. The current land use model will be calibrated to match the HEC-2 estimated peak flows, as described in Task 1.4.1. The future land use HSPF model will be refined according to this calibration and will provide flows for the events defined in Task 1.3 at points of interest that will be used in the alternatives analysis. Simulations using the future land use HSPF model will be performed without on-site detention for new development. 1.5.2 Springbrook Creek Existing HSPF models for Springbrook Creek will be updated-to reflect major changes in the current land uses and any changes to the projected future land use. The responsibility for the HSPF modeling of Springbrook Creek will be split between Entranco Engineers, who will model the East Hill drainages, and the Consultant, who will model the valley floor. The Consultant will provide Entranco Engineer with the existing model for Upper Springbrook Creek. Entranco will modify this and their existing Garrison Creek model as necessary. Entranco will provide the Consultant the time series of flows from Upper Springbrook Creek and Garrison Creek for current and future land use scenarios. The Consultant shall use these flows as input to the HSPF model for the valley floor. Tire current land use model will be'-calibrated to match the HEC-2 estimated peak flows as described in Task 1.4.1. The future land use HSPF model will be refined according to this calibration and will provide flows for the events defined in Task 1.3 at points of interest that will be used in the alternatives analysis. Simulations using the future land use HSPF model will be performed without on-site detention for new development. Additional survey data may be necessary for the HSPF model to determine flow paths for overflows from Upper Springbrook Creek above Highway 167 during flood events. This survey would be performed by the City. Take 1.6 Mi11 Creek Canyon Geomorphology Review The Consultant will review the Parametrix erosion study of Mill Creek Canyon. Preliminary review of the report suggests that there is little active downcutting of the channel bed. The Consultant will provide an in-depth review of the Parametrix report and conduct a field inspection of the canyon to determine whether there is evidence of instability hi the channel profile which may indicate the need for grade controls or other- control measures not identified by Parametrix. A brief report on the findings will be prepared. If appropriate, the Consultant will make recommendations for further hydraulic or geomorphologic analysis. Cost estimates for such work would be formulated at that time. BCCCWW0.881 4 R.W. [Beck and Associates 08/02/93 Task 1.7 Alternative Solutions Analysis The purpose of this task is to identify and develop alternative solutions to known flooding problems. 1.7.1 Mill Creek A meeting with City staff shall be held to prioritize the problems listed in the master list compiled in Task 1.4 to then be analyzed under this task. An allowance for this analysis has been budgeted to develop alternative solutions to the highest priority problems. The allowance is based on developing three alternative solutions for the five problems already identified on Mill Creek: 1) the Industrial Area, 2) Highway 167, 3) the Bowen/Scarf Ford Dealership, 4) the creek culverts under the Kent Senior Center, and 5) the two culverts downstream from the Upper Mill Creek Detention Basin. Other problems on the master list that cannot be investigated during Phase I due to budget constraints may be selected for further analysis during Phase 2. Diverting flows to downtown Kent will not be analyzed in Phase 1 as an alternative solution for the problem at the Senior Center; however, this alternative may be considered in Phase 11. Alternative configurations and sizing shall be determined using the hydraulic model developed in Task 1.4. A team meeting will be held to identify and confirm alternative solution strategies prior to conducting the analysis of the alternatives. The Consultant shall provide a task report describing the master list of current and future problems, and the identified alternative solutions and preliminary cost estimates for the five problems already identified. The estimates will include conceptual level construction costs and project overhead costs. Any property acquisition costs will be estimated with the assistance of the City. 1.7.2 Springbrook Creek A meeting with City staff shall be held to prioritize the problems listed in the master list compiled in Task 1.4 to then be analyzed under this task. An allowance for this analysis has been budgeted to develop alternative solutions to the highest priority problems. The allowance is based on developing three alternative solutions for five problems on Springbrook Creek. Other problems on the master list that cannot be investigated during Phase 1 due to budget constraints may be selected for further analysis during Phase 2. One problem has already been identified and included on the master list for Springbrook Creek. Springbrook Creek, between its confluence with Mill Creek and its East Valley Road Crossing, tends to overtop its banks during high flows. The water flows north causing flooding along S. 180th Street. Alternative solution configurations and sizing shall be determined using the hydraulic model developed in Task 1.4. A team meeting shall be held to identify and confirm alternative solution strategies prior to conducting the alternative analysis. The Consultant shall provide a task report describing the master list of current and future problems, and the identified alternative solutions and preliminary cost estimates for the one problem already identified. The estimates will include conceptual level construction costs and project overhead costs. Any property acquisition costs will be estimated with the assistance of the City. BCCCWW0.881 5 R.W. Beck and Associates 08/02/93 Task 1.8 Update Combined Stormwater Detention Enhanced Wetland Facility Simulation Results for No-Pump Alternative All of the most recent studies of the Combined Stormwater Detention Enhanced Wetland Facility (lagoon project) performance assumed that a pump station would be built at the lagoon and that pumped discharge to the Green River would be permitted for flows on the Green River at Auburn up to 12,000 cfs. One additional scenario will be simulated using HSPF for the most recent estimates of full build out land use but in which no pump station would be built. Simulations will be performed without on-site detention for new development. Results from the simulation studies will be input to the existing HEC-2 model for lower Mill Creek from the diversion site to the confluence with Springbrook Creek. Water surface profiles will be determined for the 100-year and 25-year events, and approximate areas of inundation will be mapped for the 100-year event with no pump station at the lagoon and with a 30 efs capacity pump station at the lagoon. The simulation scenarios used in the HEC-2 analyses will assume no additional on-site detention. Costs of local improvements on Mill Creek below West Valley Highway will be determined for 25-year and 100-year level of protection with and without a pump station. Results from this analysis will be used by others for an economic assessment of the benefits of a pump station at the lagoon, and to determine the appropriate level of protection. Task 1.9 Lagoons Project Coordination. The Consultant shall coordinate with and provide hydraulic and hydrologic design criteria �o CHZM Hill for the design of the combined,stormwater detention/enhanced wetland facility design (lagoon project). The Consultant shall also conduct a review of design products prepared for the lagoon project to ensure that the design criteria and requirements of the Green River Pump Operations and Procedures Plan were met. 1.9.1 Provide Lagoon Inputs The following simulated runoff hydrographs for inflow to the lagoon project will be provided: • Inflow hydrographs with an approximate 6-month recurrence interval peak flow for the diversion from Mill Creek and for inflows from the south for current and future land- use. • Inflow hydrographs with approximate 2-, 25-,and 100-year peak flows for the diversion from Mill Creek and for inflows from the south for current and future land-use. • Inflow hydrographs resulting in 2-, 25-, and 100-year peak lagoon water levels for the diversion from Mill Creek and for inflows from the south for current and future land- use for one alternative operation scenario. BCCCWW0.881 6 R.W.Beck and Associates 08/02/93 • Inflow hydrographs resulting from a spillway design storm (the design storm hyetographs are to be provided by CH2M Hill at an hourly time step). It is assumed that there will be only two inflow points to the lagoon project (one from the Mill Creek diversion and one near the SE corner of the lagoon). Data will be obtained using the updated HSPF model described under Task 1.5. 1.9.2 Provide Mill Creek Flow Diversion Characteristics Design parameters developed for the pre-design will be updated using the HSPF model results from Task 1.5. The following information will be provided: • Weir length, crest elevation, and elevation/discharge relationship • Diversion channel water surface profiles for 2-, 25-, and 100-year peak inflows for water surface elevations at the lagoon of 18-ft, 20-ft, 22-ft and 23-ft. 1.9.3 Provide Mill Creek and Green River Tailwater Ratings The following information will be provided: • Elevation/discharge relationship for the Green River at 212th Street bridge from pre-design studies • Elevation/discharge rating for Mill Creek at dhe confluence with Boeing Ditch developed from the updated HEC-2 model of Mill Creek from Task 1.4. 1.9.4 Confirm Final Lagoon Performance t The performance of the lagoon project for the final design configuration will be determined by simulation using HSPF. The simulation will include estimation of flows on Mill Creek at various points from the diversion site downstream to the confluence with Springbrook Creek. Final flows on Mill Creek will be used as input to the HEC-2 analysis for lower Mill Creek. Simulated lagoon project water levels will be subject to inundation analysis to a similar level of detail as that used in the pre-design studies. 1.9.5 Undefined Technical Support An additional 24 hours labor is included in the budget to allow for unanticipated needs for additional technical support from the Consultant in the lagoon project design. 1.9.6 Meetings The Consultant will prepare for and attend 5 meetings on the lagoon project design as required. BCCCWW0.881 7 R.W. Beck and Associates 08/02/93 1.9.7 Deliverables A report will be prepared documenting the results of the above analyses. Computer model input files, and the associated database will be provided on floppy disk. Task 1.10 Provide Technical Support for Applications to the Green River BTC The Consultant will provide technical support to the City of Kent in preparing and presenting material to the Green River Basin Technical Committee (or other relevant body) concerning proposals to modify the Green River Management Agreement and/or the Pump Operations Procedures Plan, to allow pumped discharges from the Kent Lagoons into the Green River for flows on the Green at Auburn up to 12,000 cfs. The exact scope of this work has not yet been defined. The proposed budget includes an allowance for 24 hours labor. Task 1.11 Phase 1 Task Report A final report detailing the work in Phase I will be prepared, and will include the following: • Description of the hydrologic review and analysis; including output tables and maps • Written description of HEC-2 model review and development • Flooding problems and potential solutions for Mill Creek and Springbrook Creek • The HSPF and HEC-2 models, in digital format Task 1.12 Quality Control This task will include quality control review of all major project submittals. Quality Control will be conducted by a senior staff member not involved in the development of the project. Task 1.13 Project Management The Consultant shall perform project management activities including: • Monthly invoicing and progress reporting • Subconsultant contracts and invoice monitoring • Maintaining project files • Miscellaneous client communication • Development of a project management plan • Manpower scheduling • Budget reviews BCCCWW0.881 $ R.W. Bcck and Associates 08/02/93 PHASE 2 - ALTERNATIVE SOLUTIONS ANALYSIS/RECOMMENDED SOLUTIONS Upon completion and approval by the Client of the Phase 1 task report, the Client and t11e Consultant shall negotiate the costs to complete the Phase 2 scope of work for the alternative solutions identified under Phase 1. Task 2.1 Evaluation of Alternative Solutions The purpose of this task is to evaluate and select preferred alternative solutions to solve the flooding problems identified in Task 1.7. Under this task, other problems identified by the hydraulic analysis that were not listed under Task 1.7 can be selected for further analysis and the development of alternative solutions. 2.1.1 Mill Creek To evaluate which alternative provides the best solution for each problem listed in Task 1.7.1, an evaluation matrix will be developed. In the evaluation matrix, each alternative will be evaluated according to key factors such as. degree of flood protection, environmental impacts, permitting requirements, cost, water. quality improvement, compatibility with the downstream system,maintenance,schedule,constructibility and public acceptance. This will likely require further analysis using the HEC-2 model developed in Phase 1. A team meeting will be held to evaluate and select the preferred alternatives. 2.1.2 Springbrook Creek This task is to evaluate the alternatives to the problems selected in Task 1.7.2 for Springbrook Creek. The task will involve all the same elements described in Task 2.1.1 for Mill Creek. Task 2.2 Recommended Sol ution/Prelinii nary Design 2.2.1 Mill Creek Based on the evaluation performed in Task 2.1.1, the preferred alternatives will be recommended. Preliminary designs will be developed based on the recommended alternatives, along with estimated construction costs that are more detailed than what was prepared for the alternative evaluation. In addition, operational considerations and implementation constraints will be defined. 2.2.2 Springbrook Creek Based on the evaluation performed in Task 2.1.2, the preferred alternatives will be recommended. Preliminary designs will be developed based on the recommended alternatives, along with estimated construction costs that are more detailed than what was prepared for the alternative evaluation. In addition, operational considerations and implementation constraints will be defined. BCCCWW0.881 9 R.W. Beck and Associates 08/02/93 Task 2.3 Permitting The purpose of this task is to provide the City with the technical portions of necessary permit applications for the recommended solutions. 2.3.1 Mill Creek The Consultant shall prepare a SEPA Checklist and a Declaration of Non-Significance for filing with the Department of Ecology, The infonation required to prepare the Checklist will be provided by the City. This information includes: 1. Any environmental information, materials, or reports that the City is aware of that have been prepared in the past or are currently underway that directly relate to the Mill Creek flooding problems. 2. A list and/or description of any applications pending for government approvals of other proposals directly affecting the property covered by the current proposal. 3. A description of the current zoning classification at each problem site or at each site where there is a proposed action. 4. A description of the current comprehensive plan designations at each problem site or at each. site where there is a proposed action. The Consultant shall prepare the technical portions of the applications for a Hydraulic Project Approval Permit, a Temporary Water Quality Modification Permit, and a DOT Utilities Permit. Completed applications for the permits will be provided to the City tor signing and filing with the appropriate agencies. The Consultant shall also respond to any agency questions regarding the completed applications, make any required changes to protection/mitigation measures proposed in applications based upon agency reviews and comments, and consult with the agencies to make certain changes are satisfactory. 2.3.2 Springbrook Creek The permitting tasks described in Task 2.2.1 will also be performed for Springbrook Creek. Task 2.4 Solution Phasing 2.4.1 Mill Creek We understand that solutions to all of the flooding problems will probably not be implemented at the same time. Therefore, phasing of the recommended solutions, together with implementation of the Lagoon Project, will be analyzed to determine the optimum implementation sequence. The analysis will rank the solutions based on the level of flood BCCCWW0.881 10 R. W. Beck and Associatcs 08/02/93 protection provided versus cost. The analysis will also investigate how the sequencing of the solutions might affect the total cost of solving all the problems. 2.4.2 Springbrook Creek Again, all the solutions to all of the flooding problems will probably not be implemented at the same time. Therefore, the phasing of solutions will be analyzed to determine the optimum implementation sequence. The analysis will rank the solutions based on the level of flood protection provided versus cost. The analysis will also investigate how the sequencing of the solutions might affect the total cost of solving all the problems. Task 2.5 Preliminary Design Report The Consultant shall prepare a Preliminary Design Report that discusses the flood problems and need for improvements, design criteria used to develop alternative solutions, hydrologic and hydraulic modeling, permitting, and the evaluation and selection of the recommended solutions. The report will include 11" X 17" drawings of the recommended solution preliminary designs. A draft and final report will be prepared. Five copies of the draft and ten copies of the final report will be provided to the City. Task 2.6 FEMA Analysis The City of Kent' intends to formally request to FEMA (Federal Emergency Management Agency) that revisions be made to the Flood Insurance Rate Maps for the portions of Mill Creek and Springbrook Creek that are to be studied within this scope. The Consultant shall perform base flood and floodway analyses for Mill_Creek, using the new HEC-2 model. Flows in Mill Creek will represent current land use conditions and operation of the Kent Lagoons facility. Flows on Springbrook Creek will be-determined by frequency analysis of simulated flows using input from hydrologic studies performed by Entranco and the Consultant. Work maps and flood profiles consistent with FEMA standards will be created by the Consultant. Task 2.7 Quality Control This task will include quality control review of all major project submittals. Quality Control will be conducted by a senior staff member not involved in the development of the project. Task 2.8 Project Management The Consultant shall perform project management activities including: • Monthly invoicing and progress reporting • Subconsultant contracts and invoice monitoring • Maintaining project files • Miscellaneous client communication • Development of a project management plan • Manpower scheduling • Budget reviews BCCCWW0.881 11 R. W. Beck and Associates 08/02/93 SCHEDULE City of Kent Mill Creek Stormwater Management Analysis PROJECT SCHEDULE Task Description OCT NOV DEC JAN FEB MAR APR No. — 1.1 Review Existing Data 1.1.1 Obtain and Review Other Reports 1.1.2 Survey Data = = 1.2 Field Inventory and Residents Surve 1.2.1 Mill Creek 1.2.2 S rin brook Creek 1.3 Design Criteria 1.4 Hydraulics 1.4.1 Mill Creek = 1.4.2 S rin brook Creek )OCX)C >DD 1.5—Hydrology 1.5.1 Mill Creek �CXX)OC 1.5.2 S rin brook Creek 1.6 Mill Creek Geomor holo Review __ � 1.7 Alternative Solution Identification _.. 1.7.1 Mill Creek I ---- 1.7.2 S rin brook Creek 1.8 Update Lagoon Simulation Results I i I � 1.9 Lagoons Project Coordinations 1.1 OSupportforA lication to Green River BTC 1.11 Phase I Task Rep2rt I I 1.12 Qu ality Control bC)OO)OCDO ==XX3 1.13 Project Mana ement )OCl)OC)OC�OC )OC�OC )OC>C�)OQ�C)OC>OC Fu31 6 d R � a = ' fn D c 1 n c ➢ � o 0 R g mlGmi a m a m o m m m — s m m o —-------- min N _ m rio � N g T p, n - N — s o -- -- =O p> °yxI N C N N m p O r. . om Xm m ti ti ti U � w Io aNN m m 8£ om^ (Q CD w w 3 CD a m N A N $ 8 v qq m91 N P J J 0 w N N � m m e ER m a a 31 N N 8 8 8 m — zi „ w w w w w P P � w N m m m w w to ! ..� �,��:•, ..,1. .. r" f �;'_�- ��� � � CID � C) C y �F 1 C) bf a, j . r , yq a:,•:Ilk Fj �Y n \ � G) D rn m > 71 n o m z I) .�+ m m D Z j D Z Z rD- D -C N AMENDMENT NO. 3 AGREEMENT WITH THE CITY OF KENT FOR MILL CREEK HYDROLOGIC AND HYDRAULIC ANALYSIS DATED OCTOBER 12, 1993 PART I - DESCRIPTION OF WORK Exhibit A is amended as follows. Add the following tasks: TASKS I. Investigation of maximum allowable Lagoons project water levels: Existing topographic mapping by the City of Kent will be reviewed to determine or confirm the maximum permissible water level for the Lagoons project(in consultation with CH2M Hill). If necessary, NHC will identify areas that need additional surveys. Such surveys will be performed by the City of Kent. Cost = $570 II. Create design storm events runoff files: Precipitation records at SEATAC airport will be examined to determine appropriate duration storms for volume related problems (Lagoons project) and conveyance related problems (Mill Creek flooding). Appropriate rainfall depths will be selected corresponding to these durations from published Isopluvial maps. Multipliers will be determined to transform the April 1991 storm into a 100-yr rainfall event for evaluating system storage and the Jan 1990 event into a 100-yr rainfall event for evaluating system conveyance. The WDM data file will be modified and PERLNDs and IMPLNDs (soil and vegetative cover variables) re-run to create runoff data sets for the two 100-yr storms. Cost = $735 IIIa. HSPF/Route model will be run for the case of the Lagoons project without a pump to the Green River and the following: 1. Existing land use and conveyance for both storms described under Task II. 2. Existing land use and 100-yr Mill Creek conveyance improvements for both storms described under Task II. 3. Future land use and 100-yr Mill Creek conveyance improvements for both storms described under Task II. Pile: WW-1660-CAI-AM/3001 (o:IG 1S EB U R'n M S G025.w p l) Amendment No. 3 Page 2 IIIb. HSPF/Route model will be run for the case of the Lagoons project with a pump to the Green River and the following: 4.(optional) Existing land use and conveyance for both storms described under Task II. 5.(optional) Existing land use and 100-yr Mill Creek conveyance improvements for both storms described under Task II. 6. Future land use and 100-yr Mill Creek conveyance improvements for both storms described under Task II. Task III includes modifying HSPF FTABLEs (Tables that define conveyance capacity) to account for higher flows that are expected under the 100-yr events. The route model will also be modified to explicitly consider possible submergence effects at the diversion weir. We assume all hydraulic information for the Lagoons project design provided by CH2M Hill is still valid. Budget includes time for creating all of the new data sets which will be required to store the information for later analysis. It also includes an additional allowance for extraction of results and report inclusion. Cost = $3,340 (Task IIIa) Cost = $2,016 (Task IIIb - Items 4 and 5) (optional) Cost = $1,176 (Task IIIb - Item 6) IV. Extract results for the above HSPF/Route model runs at the following locations: 1. Peak Lagoons project inflow from diversion 2. Peak Lagoons project outflows to Mill Creek 3. Peak Lagoons project stages 4. Flows in Mill Creek a. upstream and downstream of the diversion site b. downstream of the confluence with the Boeing ditch c. at the mouth of Mill Creek Cost = $340 File: WW-1660-CAI-AM/3001 (o:\G 1S GB U R 7'\M SG(Y25.w p 1) Amendment No. 3 Page 3 V. Reports A brief memorandum summarizing modifications to the HSPF/Route models, selection of the design storms, and results of the analysis will be prepared. These simulation results will also be incorporated into the Lagoons Project Coordination Section of the final Phase I Mill Creek Stormwater Management Analysis report. Cost = $1,950 VI. Meeting We will meet with the City of Kent to present the results of the analysis and discuss implications on previous hydrologic and hydraulic modeling. Cost = $860 VII. Modifying Results to Final Report (Optional): Preliminary analyses indicate that removal of the pump at the Lagoons project may not, by itself, have a significant effect on Mill Creek in terms of flood control alternatives and other work performed as part of the Mill Creek Stormwater Management Analysis (Draft Phase I Report), but it may cause the Lagoons project water levels to rise above acceptable levels. If this is the case, modifications may be required to the Lagoons project outlet to bring maximum Lagoons project water levels back to acceptable levels. Such modifications would increase peak flows in lower Mill Creek and may necessitate refinements to the flood control and hydraulic analyses for that part of the Mill Creek system below the confluence with the Boeing Ditch. A separate cost estimate is included for investigating modifications to the Lagoons project outlet and refining the flood control alternatives for lower Mill Creek as necessary. If the removal of the pump does not have a significant effect on peak Lagoons project water levels or flows in Mill Creek, then this task will not be required. The design event approach (Tasks II through IV above) for determining 100-year peak flows and stages at various points in the system will provide results somewhat different from the earlier Draft Phase I analyses. These differences could be attributed to: 1. Removal of the pump; and File: WW-1660-CAI-AW3001 (o:1GISEBURTIMSG025.wpQ Amendment No. 3 Page 4 2. Use of synthetic 100-year design events to determine 100-year conditions instead of extrapolation of simulation results from the existing 30-year record. (Use of a synthetic 100-year event reduces the uncertainty inherent in extrapolation of hydraulic conditions from the shorter historic record.) If these differences cause the Lagoons project water levels to rise above an acceptable level, then the following work will need to be done: 1. Modification of the Lagoons Project Outlet and Boeing Ditch. If the work described under Tasks I through IV shows that 100-year Lagoons project water levels exceed the maximum allowable levels, then modifications to the Lagoons project outlet or Boeing Ditch would be determined in consultation with CH2M Hill so as to bring the 100-year level down to 23 ft, or other maximum allowable level. 2. Modification of Mill Creek Flood Control Alternatives. The work described under Tasks I through IV in conjunction with possible changes to the Boeing Ditch may also result in increased peak flows in Mill Creek below the confluence with the Boeing Ditch. In this case, further analyses will be undertaken to modify the downstream flood control alternatives identified in the current draft report. The final report will be updated to reflect the no-pump simulation results. Cost = $3,090 (Optional) VIII. Update Draft Phase 1 Report to Include Additional Work Tasks: Additional work will be required to update the Phase I Mill Creek Stormwater Management Analysis report to include the above mentioned work. This would include work to incorporate new information on the Lagoons project design as well as updated text and figures associated with new flood control alternatives on lower Mill Creek. Cost = $500 IX. Additional Project Management to Finalize Lagoons Coordination: Additional project management time is required for coordinating activities related to the hydraulic design for the lagoons project. This time is allocated for attending meetings, processing contract amendments, issuing project correspondence, and engaging in telephone communications. Cost = $1,100 File: WW-1660-CAI-AM/3001 (o:1 G I S E B URT1 MSG025.w p Q Amendment No. 3 Page 5 PART I1 - PAYMENT The maximum amount to be paid to the Consultant shall be increased from $196,122.00 to $211,799.00. The Consultant will not proceed on Tasks IIIb items 4 and 5 as well as Task VII until given written notice by the City. Except as specifically modified herein, the Agreement between R. W. Beck and the City of Kent shall remain in full force and effect. Approve : City of Appro g: . W. B k By: By: Title: Title: &eD� File: WW-1660-CAI-AMl3001 (o:\GISEBURT\MSG025.wpI) COST SUMMARY TASK I $ 570 TASK II $ 735 TASK III a and IIIb item 6 $4,516 TASK IV $ 340 TASK V $1,950 TASK VI $ 860 TASK VIII $ 500 TASK IX $1,100 TOTAL COST WITHOUT OPTIONAL TASK IIIa $10,571 (Items 4 and 5) and VII OPTIONAL TASKS TASK IIIb (items 4 and 5) $2,016 TASK VII $3,090 TOTAL COST WITH OPTIONAL TASKS $15,677 File: WW-1660-CAI-AM/3001 (o:\G lSEBURT\MSG025.wpQ CONTRACT AMENDMENT NO. 4 AGREEMENT FOR CONSULTANT SERVICES BETWEEN THE CITY OF KENT AND R. W. BECK DATED MAY 21, 1995 FOR THE MILL CREEK HYDROLOGIC AND HYDRAULIC ANALYSIS PART I-DESCRIPTION OF WORK Exhibit A is amended as follows. Add the following task: A design check will be performed for four proposed culvert crossing improvements along Mill Creek The four crossings include a culvert at the Fisher Industrial Park, South 228th Street, Novak Lane, and Central Avenue. The HEC-2 model developed for Mill Creek for the Mill Creek Hydrologic and Hydraulic Analysis Project (Project) will be used to check if the culverts designed for these crossings provide conveyance equivalent to the culverts proposed in the Project Report. The budget assumes one run of the Mill Creek HEC-2 model using the 100-year storm event with the flood control modifications recommended in the Project Report. The culverts at the four crossings described above will be as designed by the City. In addition, the budget includes up to a maximum of four iterations for any modifications to the currently designed system that are necessary to meet flood control objectives. An additional model run will be made using the 25-year storm event to determine the upstream water levels with the modifications at the four crossings only. A brief letter report will be prepared that summarizes the results of this analysis. PART 11-PAYMENT The time and materials amount to be paid to the Consultant shall be increased from $211,799.00 to $216,314.00. Except as specified herein, the Agreement between R. W. Beck and the City of Kent shall remain in full force and effect. PART III-SCHEDULE R.W.Beck will make a good faith effort to complete this work by May 26, 1995. Approved: City of Kent Approved: R.W. Beck &(,-,By. L By: MAJA Z I "�X_ Don E.Wickstrom Fra chot L. Fenske Title: Director of Public Works Title: Partner File: WW-1660-CM-ANM1 (o:\WEBER\MW013.doc)