Sigma manages contracts, engineering and inspection

city of oconomowoc, waukesha county

Construction Inspection

The Sigma Group provided construction engineering and inspection services for 1.25 miles of sanitary sewer and watermain relay in the City of Oconomowoc. The project involved updating portions of Oconomowoc’s sanitary sewer and watermain systems on West Wisconsin Avenue (STH 16) and 0.5 miles of adjacent side streets ensuring completion of the work prior to roadway and bridge reconstruction scheduled to follow immediately upon completion. Portions of the work was completed adjacent to and through environmentally sensitive areas including the Oconomowoc River and Lac La Belle.


Sigma provided full contract management, construction engineering and inspection for the project consisting of:

  • Relay of watermains and commercial and residential services, sanitary sewer mains and residential and commercial service laterals;
  • Relining of existing sanitary sewer; and
  • Directionally boring watermain under the Oconomowoc River.

Sigma provided construction layout for all installations, inspected all construction, provided daily diaries and photographs documenting work performed, and provided as-builts and GIS data. Sigma also performed weekly and rain event erosion control inspections.


High capacity dewatering was required in multiple locations throughout the project. Sigma oversaw the installation, startup, and operation of the various systems installed to dewater the construction zone. The system use included:

  • Wellpoint system designed to temporarily depress the water table for an extended stretch;
  • High capacity well system to locally depress the water table; and
  • Mobile pumping operation used to dewater construction trenches as necessary.

Sigma had an inspector devoted to reviewing, documenting and evaluating the dewatering systems, particularly the discharges to local waterways.

Construction Cost Accounting

Sigma tracked quantities throughout the project, keeping alternates separated from the required bid items, prepared intermediate pay estimates and worked with the contractor to ensure accurate accounting as well as short turn-around for final payment.

Other Services

Sigma provided additional services including: the preparation of a Chapter 30 Permit for dredging activities in the Oconomowoc River and coordination with the Wisconsin Department of Transportation for the subsequent roadway improvement project.