STREAM WATER GROUP, INC.

Project Overview

The existing roadway and surrounding properties faced persistent flooding during moderate rain events due to several contributing factors. These included a low-water crossing that restricted water flow, inadequate culvert capacity unable to handle runoff efficiently, and a reduced drainage channel capacity caused by residential construction encroaching on the creek. These issues disrupted the area and posed a risk to infrastructure and property. SWG was tasked with mitigating flooding in the area while ensuring no increase in downstream flood levels.

To address these challenges, SWG conducted a comprehensive drainage study, utilizing HEC-HMS and HEC-RAS modeling to analyze hydrological and hydraulic conditions. The team prepared a detailed study report, obtained necessary flood permits, and developed construction plans and specifications. The project also included quantity and cost estimates for the proposed culvert and drainage improvements.

The scope of the project featured several critical components:

• Culvert Installation: Designed 70 linear feet of 3-7’x7’ box culverts and 70 linear feet of 3-7’x6’ and 3-6’x6’ box culverts with headwalls.
• Channel Improvements: Approximately 1,070 linear feet of drainage channel improvements, incorporating articulated concrete block (ACB) to prevent erosion and a concrete retaining wall for structural stability.
• Utility Relocation: Design for water and sewer line relocations to prevent conflicts with channel improvements and culvert installations.
• Erosion Control: Implementation of erosion control measures between and behind houses along the channel.

Additional tasks included:

• Surveying and Utility Coordination: Conducting topographic surveys and coordinating Subsurface Utility Engineering (SUE) and existing utilities.
• Environmental and Regulatory Compliance: Submitting a USACE 404 Permit waiver application and addressing environmental, geological, hydrological, floodplain, wetland, climate, biological, historical, and archeological considerations. The project also involved preparing mitigation plans and assessments for endangered species.
• Permitting: Securing urban forestry permits, grading permits, street closure documentation, and easement and right-of-way (ROW) agreements.

SWG delivered a comprehensive solution, balancing flood mitigation with regulatory compliance and environmental stewardship, ensuring the project met the community's needs and protected downstream areas.