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Home My Public Portal AboutAdd#4 - South End Drainage Phase 1.pdf P:\AGRMENTS\TYBEE ISLAND\Tybee Island Addendum 4 - South End Drainage Phase 1.doc ADDENDUM #04 ADDENDUM # #04 DATE March 22, 2018 ADDENDUM TO CONTRACT City of Tybee Island – City Engineer DATE OF CONTRACT February 28, 2018 PROJECT: CITY OF TYBEE ISLAND SOUTH END DRAINAGE STUDY PHASE 1 THE CITY OF TYBEE ISLAND (Owner) and THOMAS & HUTTON ENGINEERING CO. (Consultant/Engineer) this 22nd day of March 2018, amend their contract dated February 28, 2018 for work, materials, or services described below. I. SCOPE OF WORK: A. Survey Phase 1. Topographic Survey Phase Surveyor shall prepare a record survey of the primary, main existing stormwater conveyances for use in planning and engineering design. Secondary drainage systems will not be surveyed unless otherwise noted. The scope below is specific to each Area as shown on Exhibit A, attached to this agreement. The Consultant shall obtain vertical and horizontal data as specified in each Survey Area scope below. All survey will be on North American Vertical Datum 1988 and NAD83 Georgia State Planes, East Zone, U.S. Foot (GA83–EF). Area 1 The alignment of Area 1 can be generally defined by Stand Avenue south to 18th Street northwest to Chatham Ave, north on Chatham Ave to Inlet Avenue west to the existing outfall. From the intersection of Chatham Ave and Inlet Ave, the survey will extend north along Chatham Ave and terminate near the 15th St and Chatham Ave intersection. Alley will also be surveyed from Chatham Ave and terminate at the existing outfall. Survey will include existing drainage structure frames, inverts, pipe size, pipe material, centerline of roads near structures and curb and gutter lines, if present. Survey Area 2 The alignment of Area 2 can be generally defined by Butler Avenue from 15th St. to 12th Terrace. Survey will include existing drainage structure frames, inverts, pipe size, pipe material, centerline of roads near structures and curb and gutter lines, if present. Survey Area 3 The alignment of Area 3 generally commences immediately south of Butler Ave and 9th Terrace, extending north to 9th St and Butler Ave., City of Tybee Island Addendum #04 March 22, 2018 Page 2 P:\AGRMENTS\TYBEE ISLAND\Tybee Island Addendum 4 - South End Drainage Phase 1.doc turning west along 9th St to 2nd Ave. Survey extends from 9th St., and 1st Ave. north along 6th St. The area around the Butler Ave and the 7th St intersection will also be survey, extending north along 7th St. to 1st Ave. 6th St. will also be surveyed commencing at 6th St. and Butler Ave., north along 6th St. terminating immediately north of the 6th St. and @nd Ave. intersection. Survey will include existing drainage structure frames, inverts, pipe size, pipe material, centerline of roads near structures and curb and gutter lines, if present. Area 4 Area 4 generally consists of Memorial Park and existing stormwater infrastructure in the vicinity of the park along 4th St. Survey will include existing drainage structure frames, inverts, pipe size, pipe material, centerline of roads near structures and curb and gutter lines, if present. Highway 80 Northern Curve Survey will consist of the westbound curb line, existing drainage infrastructure. Existing Stormwater Outfalls Consultant will survey the existing outfalls to the extent accessible to obtain pipe size and material, existing grade around the outfall and any drainage structures that may be present at the outfall. Secondary drainage will not be surveyed. The intent of the survey is to provide accurate information on the flow lines and frames of the existing stormwater systems. This information will be used in preparation of a hydrologic and hydraulic analysis (model) to determine areas of significant flooding during various design storms. Survey Phase Lump Sum $22,250.00 B. General Study/Report Phases In preparation of identifying stormwater improvement projects and costs, existing stormwater system deficiencies must first be identified. The scope of this task includes using survey performed under this contract and performing a hydrologic and hydraulic analysis of the existing primary stormwater conveyances identified in within the Areas shown in Exhibit A. The Consultant shall create an ICPR 4, 1– Dimensional model to simulate stormwater flow through the existing stormwater system. The hydrologic and hydraulic model will include primary existing stormwater conveyances within the Areas, as shown on Exhibit A, simulated to the 25–year, 24–hour design storm. Drainage basins will be delineated and mapped. Time of concentration and curve calculations will be in accordance with USDA Technical Release 55 guidance. After model simulations, the water surface elevations will be reviewed in relation to drainage structure frame elevations for areas of flooding known as stormwater system deficiencies. The identified City of Tybee Island Addendum #04 March 22, 2018 Page 3 P:\AGRMENTS\TYBEE ISLAND\Tybee Island Addendum 4 - South End Drainage Phase 1.doc deficiencies will be identified on an exhibit for further investigation in Phase II of the project. The Consultant will use Mean High High Water as the tailwater for the model. Deliverables for this phase will include: • ICPR 4, 1–dimensional model simulating existing stormwater conveyance for the 25–year, 24–hour design storm. • An exhibit indicating areas of simulated flooding for further evaluation. General Study/Reports Phase Lump Sum $22,500.00 C. Exclusions Items not included in the scope of services are as follows: • Design • Permit • Cost Estimating • Construction Services • Determination of Improvements and Associated Costs • Accessibility construction compliance verification • Archaeological survey and report • Wetland, Coastal Marshland delineation, surveys, or permits • Geotechnical investigation or report • Phase One or Phase Two Environmental Assessments • Endangered species survey and report • Off–site work unless specifically covered in the scope of services • Approvals or permits other than those related to the scope of work covered by this contract • Act as an expert witness for legal activities • Georgia Department of Transportation permits or approvals. • Telephones, cable television, gas, and power distribution systems These items can be coordinated or provided, if requested by the Owner in writing. 2. PERIODS OF SERVICE A. Exhibit Phase After receipt of a written notice to proceed from the Owner, Consultant will commence and complete work upon a mutually agreed upon schedule between Owner and Consultant. City of Tybee Island Addendum #04 March 22, 2018 Page 4 P:\AGRMENTS\TYBEE ISLAND\Tybee Island Addendum 4 - South End Drainage Phase 1.doc The above fee arrangements are on the basis of prompt payment of our invoices and the orderly and continuous progress of the Project. Project related costs for all printing, travel, reproductions, and materials will be billed as reimbursable expenses. When approved by both parties this Addendum becomes a legal document and a part of and subject to Terms and Conditions of said Contract. APPROVED: APPROVED: THOMAS & HUTTON ENGINEERING CO. CITY OF TYBEE ISLAND By: By: A. Chris Stovall, P.E. Jason Buelterman Title: Principal/Project Manager Title: Mayor Date: Date: