Hartford Wet Weather Expansion Project

Type	Physical Modeling, Numerical Modeling
Markets	Waste Water, Water Treatment, Municipal
Applications	Hydraulic Structures, Pump Intake, Screening & Grit Facility, Pump Discharge

An undistorted 1:6 scale model of the influent headworks structure evaluate the flow patterns1 / 5

Hydraulic conditions of the project's influent wet well pump station were evaluated per Hydraulic Institute acceptance criteria2 / 5

An undistorted 1:5.84 scale model of the influent pump station tested for an array of operating conditions to evaluate for vortex formation and swirl3 / 5

An undistorted 1:6 scale model of the influent headworks structure was used to evaluate and derive design modifications to reduce grit deposition4 / 5

A 1:8.4 scale model evaluated the effluent pump station for adverse conditions that would afffect performance5 / 5

This multifaceted project used several physical and computational hydraulic model studies to help ensure the performance of the proposed designs. Conducted for the Hartford Water Pollution Control Facility Wet Weather Expansion, the focus areas included the influent headworks structure, the influent pump station, the combined effluent pump station, the CSO pump station, and air flow in the CSO tunnel system.

Work Performed

Influent Headworks Structure:

An undistorted 1:6 scale model of the influent headworks structure was developed and tested to evaluate the flow patterns and water levels in the baseline configuration of the headworks, as well as the flow distribution between the operating fine screen channels and operating grit channels, to determine the distribution of grit to the grit channels. The model was used to derive and evaluate design modifications that would significantly reduce grit deposition and improve flow distribution between the channels.

Influent Pump Station:

An undistorted 1:5.84 scale model of the influent pump station was designed, constructed and tested, including an array of operating scenarios that were evaluated for vortex formation and swirl that may adversely pump performance. Also, the flow split between the screening channels was determined and modified to provide uniformity.

Combined Effluent Pump Station:

Alden designed, constructed and tested an 1: 8.14 scale model of the effluent pump station to evaluate and mitigate flow patterns, free and subsurface vortex formation, swirl and potential for air entrainment that would adversely affect performance.

Combined Sewer Overflow Pump Station:

A 1:4 scale model of the new closed conduit combined sewer overflow (CSO) pump station was developed and tested to evaluate and improve hydraulic performance. Design modifications were made to mitigate swirl and vortexing problems.

Odor Control Design:

A three-dimensional computational fluid dynamics (CFD) model study of the tunnel system was conducted to: (1) determine the air flow exhaust rates from an empty tunnel during winter months where the air in the tunnel would be warmer than the ambient air; and (2) determine the air flow exhaust rates caused by tunnel filling during an extreme storm.