The vendor is required to provide that stormwater management consulting services.
- Implementation of the following items will be required by the permit. vendor must have experience and knowledge regarding these program elements.
• Structural controls and storm water collection system operation: the operation of the storm sewer collection system, storm water conveyance system, outfalls, structural controls, best management practices (BMPS) for quantity and quality control, etc. shall be maintained in a manner to reduce the discharge of pollutants to the maximum extent practicable (MEP).
• Areas of new development and significant redevelopment: a comprehensive master planning process must be in place to achieve the "MEP" standards to reduce the discharge of pollutants, after construction is completed, from ms4s which receive discharges from areas of new development and significant redevelopment.
• Existing roadway: all roadways shall be maintained and operated in a manner to reduce the discharge of pollutants to the "MEP".
• Flood control project: storm water problems related to flooding in selected watersheds will be analyzed and recommendation of potential solutions to the problems identified
• Municipal waste treatment, storage, or disposal facilities: municipal water treatment, storage, or disposal facilities not covered by a national pollution discharge elimination (NPDES) storm water permit must monitor sources of pollutants and reduce pollutants in storm water discharges to the "MEP".
• Pesticide, herbicide, and fertilizers application: identified impairments potentially caused by PHF application activities shall be abated at the sources to the "MEP
• Illicit discharges and improper disposal: a program to detect and eliminate illicit and improper disposal of non-storm water discharges must be in place.
• Industrial and high-risk runoff: continue to identify, monitor, and control discharge of pollutants to the "MEP" from landfills, hazardous water treatment, storage, disposal and recovery facilities, and other industrial facilities.
• Monitoring data collection: recommend continuous improvement to the comprehensive monitoring program for storm water runoff as required by the permit.
• Public involvement and public education: provide recommendations for a program to involve and educate the public concerning pollutants associated with storm water runoff.
- The following general tasks are based on the main program elements listed above
1. Structural controls and storm water collection system operation
• The consultant would be responsible for the proper disposal of hazardous waste produced by the sampling effort.
• Currently we are using city works AMS software application that is used to inventory field bmp’s, store data and pictures, track inspection results and provide a month status report.
• The vendor should be able to assist with changes to the software program to meet overall documentation needs.
• Provide technical support to county staff in outfall inventory, detention pond and post development bmp updates and new technologies and documentation recommendations such as data collection hardware and software, camera, GPS receivers.
2. Structural controls and storm water collection system operation
• Continue the development of watershed master plans to identify water quality problems, areas of concern and POCs for the WMU'S as progress is made by watershed. identify potential retrofit projects in the priority WMU’S.
• Provide analysis of baseline and storm event-based parameters of flow and pollutant concentration for potential retrofit projects to show potential improvements to water quality.
• Provide technical assistance for any needed changes to our design manual's post construction water quality standard requirements, methods, techniques, specifications or standard details
• Provide engineering design services related to project design, permitting, bidding/award assistance and construction observation services for retrofit and stream stabilization projects.
- Flood control project
a. Data collection
• Obtain digital information from appropriate sources and compile topographic/planimetric maps that will provide the data needed for the hydrologic and hydraulic modeling of the watershed.
• Obtain available historical precipitation data, high water marks and historical flood data for use in model verification.
b. Field investigation
• Collect field information and perform field reconnaissance to identify structures, conditions and parameters affecting hydrologic performance of the primary drainage system for the watershed.
• Collect physical measurements of channels and structures affecting hydraulic performance of the stream reaches to be studied.
• Obtain field surveyed data to adequately model street crossings, stream cross-sections, and other critical features that are part of the studied stream reaches.
c. Survey
• Identify and survey the invert elevations and roadway overtopping elevations for road crossings within the watershed.
• Perform surveys of structures identified as within or adjacent to the floodplain.
• Utilize surveys performed using established benchmarks to prioritize structures for possible flood mitigation. d. Hydrologic modeling and analysis
• Prepare a hydrologic model of the watershed using the HEC-RAS model developed by the us army corps of engineers, hydrologic engineering center.
• Update the hydrology associated with new and existing FEMA flood insurance studies to reflect current conditions and predict future conditions.
• Utilize new existing conditions hydrology to identify probable existing level of service for each bridge and culvert on the mainstem and tributaries.
• Delineate sub-watersheds at points and areas that are critical to evaluation and mitigation of known flooding problems.
• Review and update the county's existing land use data to reflect the most up- to-date land use conditions.
• If requested, develop a future land use map using the existing land use data and projected development as directed by the county.
• Calculate hydrologic parameters (SCS unit hydrograph method) for each of the sub watersheds using land-use and soils data provided by the county.
• Develop routing parameters (modified Puls method) for all stream reaches that are within the corresponding HEC-RAS model.
• Develop routing parameters (muskingum-cunge method) for all stream reaches that are not included within the corresponding HEC-RAS model.
• Develop routing parameters for major detention structures.
• Compute runoff hydrographs at the downstream end of each sub-watershed.
• Combine and route runoff hydrographs so that a comprehensive assessment of the watershed response to each rainfall event is obtained.
• Verify model results using available historical data; calculate and compare USGS regression flows to the Model results.
• Compare model results to the FEMA FIS where applicable.
e. Hydraulic analysis
• Prepare a hydraulic model of the watershed using the HEC-RAS model developed by the us army corps of engineers, hydrologic engineering center; convert mainstream hec-2 model to HEC-RAS
• Develop cross sections using county topographic data along with field measured channel dimensions.
• Incorporate bridge, culvert, and pond data collected during the field work into the model and update the hydraulic model for critical infrastructure (those bridges or culvers with known flooding issues and those modeled at or below the desired level of service); verify current and future level of service.
• Verify model results using available historical data. compare model results to the FEMA FIS where applicable.
• Analyze the water surface profiles associated with the 2, 10, 25, 50, 100 and 500 year, 24-hr storm events for existing basin conditions.
• If requested, complete a floodway analysis for all streams included in the HEC- RAS model.
- Questions/Inquires Deadline: April 02, 2025