Lewis & Zimmerman Associates in association with its affiliate, the Construction Dynamics Group, conducted two constructibility reviews on upgrade projects at the Blue Plains Wastewater Treatment Plant, Washington, D.C.

The Chlorine Building No.1 and 2 Upgrades project modified and replaced existing equipment that received chlorine from a train tanker car, mixed it with water, and injected it into various parts of the wastewater stream.

The Biological Nutrient Removal (BNR) Treatment Trains Upgrade project enables WASA to replace the aeration piping and diffusers in the BNR tanks, aerate sewage-conveying conduits, install new baffles, and replace gates. In the associated secondary clarifiers, the effluent troughs were repositioned and the sludge collectors were replaced.

In both instances, the constructibility review team uncovered discrepancies within the drawings for each discipline and inconsistencies among the drawings of multiple disciplines addressing the same change. In addition, a site visit uncovered that some existing conditions were not addressed in the contract documents. The review assisted WASA in finalizing bid documents and minimizing risk.

Henrico County Water Reclamation Plant Phase III Upgrades

Lewis & Zimmerman Associates, in association with its sister company, the Construction Dynamics Group, conducted a three-day constructibility review of the Phase III Upgrade of the Henrico County Water Reclamation Plant. The plant revisions include the addition of a third primary digester, conversion of the dissolved air flotation thickeners to sludge blending tanks, and the conversion of an in-vessel composting facility to a solids handling facility containing gravity belt thickeners for secondary sludge, centrifuges for the blended sludge, and additional sludge storage facilities.

The documents were in good condition. However, the reviewers uncovered some coordination lapses both within and amongst the various discipline drawings. Some of the specifications were not specifically for this project but referencing items for other projects. Some areas, such as the sludge storage shed, were not yet completed at the time of the review. Constructibility reviews are valuable because the team views the project from the contractor's perspective and thus minimizes the potential for change orders and claims during construction.