R2021-09 Resolution Authorizing a Professional Engineering Services Agreement with Clark Dietz Inc. to Provide Final Design Services for the Brush College and Reas Bridge Lift Station and Forcemain City Project 2020-06

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BRUSH COLLEGE ROAD SEWER STUDY ( City of Decatur Table 3.Preliminary Opinion of Probable Project Costs Gravity Sewer $240,000 $1,650,500 $0 Pump Station $640,000 $75,000 $500,000 Forcemain $1,150,000 $0 $1,150,000 Land Acquisition/Easement $80,000 $0 $0 Addt'I Pump Station and FM $0 $0 $1,500,000 Damon Downstream Sewer Study $0 $150,000 $0 Contingency(30%) $633,000 $517,650 $945,000 Design Engineering(8%) $168,800 $138,040 $252,000 Construction Engineering(6%) $126,600 $103,530 $189,000 Total $3,038,400 $2,634,720 $4,536,000 Recommendations We recommend that for planning of this Service Area, improvements be divided into three phases as described herein.This phasing allows for reasonable capital expenditures and will avoid oversizing planned infrastructure before it is needed. Design of the first two phases should be such to anticipate Phase III flows for flexibility. Phase I recommendations include the following improvements: • The City purchase a 1-arce parcel for pump station at the Brush College Road and Reas Bridge Road intersection.Access to the pump station site should minimize traffic conflicts and be designed with enough space for operations and maintenance. • A new pump station with a wetwell sized for Phase II flows,valve vault,electrical controls,and generator.The pump station will also include two 30 hp pumps submersible pumps designed to SDD's design requirements for their operation and control. Physical space and electrical capacity should be available for Phase II flows, but the additional pump required for Phase II will not be installed. • An 8"forcemain will be installed along Hubbard Road to 27th Street. • Approximately 1,500 feet of gravity sewer will be install south along Brush College Road to provide service for the initial developments. Phase II recommendations include: • Prior to any improvement work,a sewer capacity study downstream of the Damon Avenue pump station is required to satisfy SDD's concerns about the remaining capacity in this sewer.This capacity study should: o Review the design capacity(slopes, pipe size,downstream constraints), o Televise to identify pipe condition, o Install flow monitoring at several locations along length of the sewer and collect several months of data, o Analyze the impact of rain events on sewer flow rates as compared to dry weather flow to determine how much of the capacity of the sewer is utilized during various design rainfall events, o Predict the likelihood and location of CSO/SSO events currently and with any additional flow from new developments in the service area,and o Recommend improvements and maximum remain capacity o Note:Any additional improvements recommended by the sewer capacity study downstream of the Damon Avenue pump station are not included here or in the cost estimates. • Add one additional 30-hp pump to the pump station. • Provide approximately 8,300 feet of additional gravity sewer to service new developments.These new gravity sewers should be installed as demand requires. Clark Dietz,Inc. 6 January 2021