One of the services NTH provides is Civil-Site Design. Our Civil-Design team consists of degreed civil engineers (all on track for professional engineering licensure in the next year) completing engineering analysis and design as it relates to site development. Got a green site where a new office complex needs to go? Maybe an existing industrial site that is being retrofitted for a new use? It all starts with the Civil-Site design! Initial topographic survey, site layout, traffic turning movements, grading, cut-fill analysis, utility layout and design…our Civil-Site Design can analyze these elements and develop contract documents to detail the design.

Land developers face many constraints as they plan the utilization of their property. Municipal planning ordinances which prescribe building coverage ratios, setbacks, and parking requirements affect site layout, as well as conservation of natural resources such as woodlands and wetlands. Storm water management requirements and the location of the storm water outlet also impact site planning. The Civil-Site Design group has the experience to work with developers and public agencies to optimize utilization of a site. We utilize the latest software design packages including AutoCAD Civil 3D, Auto Turn, and Storm and Sanitary Analysis, to accurately and efficiently design-out the site. We can convert the approved site plan into engineering construction plans and specifications to be used for permitting, bidding and construction. Contract documents typically include soil erosion control plans and specifications, traffic control plans, demolition plans, utility plans, layout plans, and grading plans.

Our group has extensive experience designing roads and underground utilities, including water supply, sanitary sewers, pump stations and storm water management facilities. We have designed Low Impact Development (LID) infrastructure including green infrastructure elements such as rain gardens, bioswales, and permeable pavements. We can also prepare permit applications for local and state approval and are routinely involved in the construction administration process including probable cost opinion preparation, review of project submittals / contractor payment applications, and verification of material/ workmanship compliance with project specifications.

In November of 2013, NTH Consultants, Ltd. was retained as the prime consultant by the Oakland County Water Resources Commissioner’s Office to conduct an investigation into the cause of a sinkhole that developed in Southfield, Michigan. NTH’s analysis lead to a repair effort to stabilize the undermined foundations of the culvert and floor of the box sections that carry the drain beneath the service drive of Northwestern Highway (M-10) in Southfield, Michigan. 

NTH’s unique contribution to the project was the inspection team’s discovery that the natural soil bottom within the portion of the culvert that extends beneath the MDOT ROW was eroded due to flow conditions within the drain. NTH was able to quickly identify that the discharge from these pipes projected away from the culvert walls in a jet that struck the channel bottom within the culvert. Because the pipes are connected to the roadway surface drainage system and convey flow from relatively nearby catch basins and other stormwater management structures, during short, intense precipitation events the maximum discharge from the pipes likely would occur before maximum flow is reached. Accordingly, the water depth within the culvert could remain relatively shallow and not provide much “cushion/dissipation” for the jets from the two pipes, leading to erosion of the channel bottom.

Through NTH’s quick response, planning and action, the team was able to:

• Stabilize the undermined features
• Fill remaining void space beneath and surrounding the three-sided culver and box drain
• Create a floor to prevent future undermining at the downstream end of the box drain
• Allow for traffic to be maintained on both the Northwestern Highway mainline and the service drive without interruption
• Avoid the use of access shafts which speeded construction and reduced impact on the operations of nearby businesses

 
​This project demonstrates a practical approach to addressing scouring and loss of support beneath culvert footings of similar construction. Because a similar design approach was used at other locations along Northwestern Highway and elsewhere, it is possible that this type of repair may be required elsewhere along the highway. In addition, it appears that since similar design was common for other MDOT projects built in the same time frame, routine inspection of such culverts is necessary, and similar repairs may be required on many other roadways throughout the state.