Scope of Work
The Consultant shall coordinate with City staff to develop a Drainage Master Plan. The proposed project process and deliverables shall evaluate and address the following tasks relevant to the development of a Drainage Master Plan for the City of Seguin.
(a) Hydraulic and Hydrologic Model Development
i. Data Collection and Review – The Consultant will provide City staff with a list of necessary data including terrain (LiDAR) data, land use/zoning, FEMA (both mapping and loss data), planimetric, political boundaries, development and subdivisions, 311 data and drainage complaints, utility information, parcel information, etc. The Consultant will review received data and create a data log for tracking purposes and also identify apparent data deficiencies.
ii. Hydraulic and Hydrologic Model Development – The Consultant will develop a model that is representative of exiting drainage areas. Calibration of the H&H model is required. The City has knowledge of HEC-HMS and HEC-RAS models for: Walnut Branch CLOMR, Mays Creek LOMR, and North Guadalupe, North Heideke, Mays Creek, and Walnut Branch GLO Projects.
iii. Model Development Documentation – The Consultant will prepare a technical memorandum documenting development of the existing condition hydraulic and hydrologic model.
(b) Review Drainage Policy and Criteria Development – the Consultant will review the current drainage policies.
(c) Existing Storm Sewer Assessment – The Consultant will evaluate and determine the capacity of the existing storm sewer systems, detention ponds, and open channels within the limits of the City of Seguin. Further, all outfalls to the Guadalupe River and tributaries and level of service analysis for existing storm sewer systems shall be identified.
(d) Master Plan Development
i. Identify Conceptual Project Locations – The Consultant will identify areas of low water crossings, single-access neighborhoods, and areas of flood risk.
ii. Select Potential Projects and Develop Prioritized Projects List – Potential projects will be evaluated based on safety (structure flooding, street flooding, and downstream impacts), project cost, funding availability, environmental impact, project timing, social impacts, constructability, and stakeholder impacts. A Benefit-Cost Analysis shall be conducted by the Consultant.
iii. Submit Draft Report
iv. Public Meetings
v. Submit Final Report
(e) Floodplain Study and Remapping – The Consultant will compare model results to the effective Digital Flood Insurance Rate Map (DFIRM) data and the flood insurance claim data provided. The Consultant will compare the effective floodplain to specific claim locations to help determine if the flooding is riverine (floodplain) or possibly caused by localized (site specific) drainage issues.
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