Drainage Study. When authorized, conduct a detailed study to explore alternative design concepts concerning drainage for the PROJECT. Present the findings in writing identifying recommendations to the CITY, including preliminary cost estimates, prior to development of field check plans. Such written findings and recommendations must be in a format which is self-explanatory and readily un- derstood by persons with average backgrounds for the technology involved.
Drainage Study. 1. Perform a drainage study of the project watershed
Drainage Study a. HYDROLOGIC/HYDRAULIC MODELING (1 major channel crossing, 7 cross drainage structures assumed): • Prepare hydrologic and hydraulic models or modify existing models (FEMA, drainage districts, river authorities, cities, etc.) if available, to define the drainage infrastructure required for the project. Detail the methodologies employed and recommendations. The analysis will include: preparation of a preliminary design of the right of way drainage system; preliminary sizing of cross drainage structures and major channel crossings to reflect the existing and proposed conditions; recommended minimum pavement elevations based on cross drainage flood elevations; right-of-way requirements; identify potential needs for FEMA Coordination. HEC-RAS shall be utilized for all stream modeling. HY-8 shall be used for non-bridge class culverts. • Develop existing channel cross sections based on data collection. • Exhibits and analysis will be prepared in the GIS environment to the extent practical. • Onsite parallel drainage for ditch and/or storm sewer sizing will only be analyzed to determine project ROW needs. Detailed inlet level calculations are not included in this scope. • Coordinate with the Upper Brushy Creek Water Control Improvement District (UBCWCID) as necessary throughout the project.
Drainage Study. 1. Perform a drainage study of the Project watershed to determine the drainage requirements for the Project.
Drainage Study. The Consultant will prepare, submit, and obtain approval of a Drainage Impact Analysis. This analysis will identify the changes in peak flows due to the proposed roadway improvements and recommend drainage measures to mitigate the impacts associated with the proposed improvements. This study will include the evaluation of the existing storm sewer systems and recommend preliminary size detention basin or an enlarged storm sewer system so as not to impact the receiving streams or the abutting property. The purpose of this task is to prepare a Drainage Mitigation Impact Analysis Study to determine the 100-year storm impacts resulting from construction of the project and to develop and analyze alternatives to mitigate these impacts. The following tasks describe the work to be performed: Prepare 100-year storm drainage area maps for existing and proposed conditions, which includes the southbound lanes, within the project right of way (ROW) and any off-site areas draining into the ROW. Compute existing and proposed peak flows with standard TxDOT methodology within the ROW. The Rational Method will be used to compute these flows for drainage areas less than 200 acres and the Small Watershed Method will be used to evaluate the impacts of the ultimate conditions. HEC- HMS modeling will be used for drainage areas equal to or greater than 200 acres. Compute required 100-year storage volumes within the ROW using the average end area method to determine mitigation requirements for the proposed condition versus existing conditions. Prepare existing and proposed hydrographs at each outfall location to develop mitigation alternatives to implement the required 100-year mitigation. Alternatives may include increasing storm sewer sizes beyond what is required for the design 10-year storm or improving existing roadside ditches/ or providing a detention site required within the vicinity. The location of the detention site may vary and further analysis depending on the location will be needed. Prepare construction cost estimates for mitigation alternatives developed in the previous task to assist in selecting the most cost effective mitigation methods. Prepare a Drainage Mitigation Study report to summarize and document the findings of this study. The report will include the following items at a minimum: o Conceptual and generic discussions of mitigation alternatives considered o Comparative costs associated with each alternative o Recommended mitigation solutions o...
Drainage Study. At the City’s written request, the Consultant shall: Prepare a drainage study for the project in addition to the work provided in exhibit A.
Drainage Study. The Engineer shall use data from as-built plans and FEMA maps to locate drainage outfall(s) in order to determine existing culvert sizes, design flows, and water surface elevations for use in the design of roadway geometry. The Engineer shall conduct a Preliminary Drainage Study to determine and evaluate the adequacy of the ROW needed to accommodate the ditch profile and side slopes. The study shall identify the water surface elevations for the 2, 5, 10, 25, 50 and 100 year storm event, identify and locate outfalls, provide overall drainage area map, sub- drainage area map, and provide a drainage study report identifying the results of the study.
Drainage Study. The Engineer shall conduct a Drainage Study to determine and evaluate the adequacy of the ROW needed to accommodate the proposed roadway and cross drainage systems. Hydrology and hydraulic analyses shall be completed for 2 major road crossings along Long Branch of Muddy Creek and Stream 2E3/2E4 confluence in accordance with TxDOT design methods. The drainage report shall be signed and sealed by a professional engineer. The Drainage Study methodology will be in accordance with the State’s Hydraulic Design Manual, District criteria, and any specific guidance provided by the State.
Drainage Study a. Hydrologic Study & Modeling Detail the criteria, methodologies, results and recommendations of the analysis. • Collect, prepare and modify existing hydrologic & hydraulic models to reflect the existing & proposed schematic. Compare and document the study results with existing studies or models from the County, FEMA, cities, etc., if available. • Provide existing and proposed condition drainage area maps for each outfall from the project area and/or each cross-drainage structure location. • Provide a comparison of existing vs proposed condition runoff patterns at each outfall from the project area. • Atlas 14 impacts will be reviewed and incorporated.
Drainage Study. Analyze the existing pre-development and post- development stormwater runoff calculations and determine the potential capacity and adequacy of the receiving system. Design stormwater treatment, infiltration chamber system, and infiltration and peak flowrate control devices. Prepare a drainage study to be submitted to the City of Nashua.
