Consulting Services : Interior Drainage Study

2026-11-03

The primary objective is to provide modeling that reflects the effects of City owned retention ponds , storm sewer , drainage channels , and levee . This modeling will be provided to FEMA so that their flood remapping is realistic to the actual conditions . The other primary objective is to use this modeling to justify the recertification of the City Levee to the USACE . The secondary objective of this comprehensive drainage study is to evaluate the existing drainage infrastructure , identify deficiencies , and propose actionable solutions to enhance the city ' s flood management capability . This will also facilitate better communication and coordination with FEMA and the USACE . Scope of Work The comprehensive drainage study will cover the following components : 1 . Existing Conditions Analysis GIS Data Assessment : • Review the existing GIS data , which includes information on storm pipe sizes , manholes , and inlets . • Identify gaps in the current data , particularly concerning invert elevations , which are approximately 20 % complete . • Make necessary assumptions or simplifications to efficiently complete the study . • Mapping will include all storm pipe sizes 18 - inches and larger . Field Survey : • Conduct field surveys to fill in missing data , especially for critical areas where invert elevations are not available . • Verify the accuracy of existing GIS data and update it as needed . 2 . Hydrologic and Hydraulic Modeling Model Development : • Develop a hydrologic and hydraulic model of the city ’ s drainage system . The model will include :  Storm pipes 18 inches or larger .  Detention ponds .  Lift stations & force mains  Overland conveyance networks such as streets and drainage channels ( natural and manmade ).  Flood control systems . • Use suitable modeling software , taking into consideration the industry ' s current standards and hydraulic models meeting FEMA ’ s minimum requirements of the NFIP . Existing Conditions Simulation : • Simulate existing conditions to identify areas prone to flooding and assess the current system ’ s performance ...

South Dakota

2026-04-08