K-4 - Professional Services Agreement - Highway 6 Reconstruction - MSA

• Structure Design: o Develop plans for a new twin cell box culvert located approximately 0.2 miles west of the intersection of USH 6 and Park Road to replace the existing multi-cell box culvert at that location. The structure will have parallel wing headwalls and a zero degree skew, and the plans will reference the Iowa DOT’s culvert standards. The top of the slab will be buried and independent from the pavement structure, but due to limited fill over the structure it will be cast-in-place. A precast culvert option is not included. Standard open metal safety rail will be mounted to the southern parapet and wingwalls using standard drawings. The parapets will be located outside the clear zone and traffic barrier is not required. o Develop plans for a new single cell box culvert located approximately 0.3 miles west of the intersection of USH 6 and Park Road to replace the existing single-cell box culvert at that location. The structure will have either parallel or flared wing headwalls and a standard skew (15, 30, or 45 degrees), with both ends having similar wing details. The plans will reference the Iowa DOT’s culvert standards. The top of the slab will be buried and independent from the pavement structure, but due to limited fill over the structure it will be cast-in-place. A precast culvert option is not included. Standard open metal safety rail will be mounted to the southern parapet and wingwalls using standard drawings. The parapets will be located outside the clear zone and traffic barrier is not required. o Develop plans for a box culvert extension at the existing single cell box culvert located approximately 0.05 miles west of the intersection of USH 6 and Stephans Street. Both ends of the box will be extended, and the wings will be flared to match existing conditions. The box culvert extensions will be cast-in-place to match the existing cast-in-place structure. Standard open metal safety rail will be mounted to the southern parapet and wingwalls using standard drawings. • Erosion Control Design: o Determine location and type of erosion control devices needed to meet regulatory requirements for a National Pollutant Discharge Elimination System (NPDES) permit. o Develop a Pollution Prevention Plan (PPP) for inclusion in the plans. • Traffic Control Design: Develop traffic control plans detailing temporary traffic control devices and signage required to construct the project under traffic. • Construction Cost Estimate: