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Volume 31, Issue 4

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Monday, 29 October 2007 03:10

The Drying of Chicago

Written by  Charles H. Wyatt
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The now “infamous” tunnel system found under the heart of Chicago’s business center—the Loop—was first planned in 1899 as a four foot bore to carry telephone cables and protect them from interruptions in service caused by downed telephone poles.

In 1903 the City Council granted a franchise to expand the tunnel to its current size, seven and a half feet high, six feet wide at its widest part, and five feet wide at the bottom. It had a flat-bottomed oval shape to enable electric locomotives to haul freight, coal, ashes, etc., throughout its 62 mile length. Also, the tunnel has a one foot thick unreinforced concrete lining.

The City of Chicago became the owner of the tunnel system in 1959 when the last firm to operate the tunnel, Chicago Tunnel Company, went bankrupt. The maintenance was the responsibility of the City News until 1962 at which time it too was assumed by the City.

Water, Water Everywhere
But Not a Drop to Drink

On January 14, 1992, two workers from Chicago Cable Television noticed a visible cave-in inside the tunnel at the Kinzie Street Bridge. Repair plans were drawn up by the City and submitted to contractors for bids. Unfortunately the bids exceeded the estimated cost and additional meetings were scheduled regarding the repair project.

However, the Chicago River did not wait for these meetings to be held. On April 13, 1992, at 5:57 a.m. the first call to the Chicago Fire Department was received from a building engineer at the Chicago Merchandise Mart. By the time the Fire Department personnel reached the Mart, the water inside the building( the boiler room level) had risen from a few inches to two feet. By late afternoon the level had risen to 17 feet.

Within the first two hours calls reporting building flooding came from nine more buildings, including City Hall. By 9:00 a.m. there was eleven feet of water in the lowest basement of City Hall and the building was ordered evacuated.

Other buildings soon followed suit and power shutdowns by Commonwealth Edison were ordered. By the end of the day it was estimated that 23 buildings had water related emergencies.
However, the leak had not been plugged and water continued to flow though the tunnel system into the basements of the office buildings in the Central Business District.

By the time the leak at the Kinzie Bridge had been sealed at least 200 buildings were without power and over 250 million gallons of potentially contaminated, polluted water from the Chicago River had entered the tunnel system and the buildings inside the Loop. Some of these buildings had as much as 40 feet of water in their basement(s).

Water Related Emergencies

Since the majority of the buildings had been evacuated during time of flooding, the bodily injury to personnel was minimal. Initial reports listed only three minor injuries and these were due to the evacuation and not the flooding itself.

Impact of the flood was staggering. An estimated 25,000 workers had been sent home costing business approximately $40 million in lost productivity in addition to the financial hardships encountered by many due to lost wages. Repairing the damage would cost in the $100’s of millions. Many problems had to be resolved, such as:

1. How to drain/pump all the water from the buildings and tunnels.
2. How to restore the air quality in the work areas to enable the repair personnel to work efficiently and not need breathing apparatus.
3. How to restore the power distribution systems within the individual buildings and the Loop as a whole.
4. How to restore the cooling and boiler plants essential to the operations of the buildings.
5 How to restore the financial/computer operations so necessary to the operations of modern day businesses.
6. How to restore the air quality within the buildings and make them safe for employees to return to work.

The Use of Refrigerated
Dehumidification Equipment

Since all of the above problems were water related, all efforts in the restoration process had to deal initially with the removal of this water. Very obviously many large pumps were utilized to remove the bulk quantities of water throughout the system.

The value of dehumidification equipment in this operation was minimal. However, refrigerated dehumidification equipment was invaluable in the solution of the other above problems.

Because of the successful work relationship that occurred during the restoration efforts in the Charleston, South Carolina area after Hurricane Hugo, INRECON, a 40 year old insurance reconstruction firm headquartered in Dearborn, Michigan, contacted Enviro-Air Control Corporation, a manufacturer and lessor of refrigerated dehumidification equipment located in Houston, Texas, and the two companies began their work.

Both companies marshalled their equipment and personnel in Chicago as the water was being pumped out of the basements.

The initial project was started at a central business district landmark—the 1 N. LaSalle building.

One of the major problems was the poor air quality in the basement work areas. The air was stagnant.

“Due to the amount of contaminated water that entered the buildings it would have been necessary for employees to wear controlled breathing apparatus to remain in many of the work areas for extended periods of time,” stated George Fenton, Vice President, Sales & Marketing of INRECON.

To reduce this problem, refrigerated, dehumidified and filtered “good air” was supplied to the basements to allow building, insurance, and repair personnel to enter the basements and prepare a critical path program to get the buildings back in operation as soon as possible. Dehumidification equipment was crucial to the restoration effort. The dehumidification units, located outside the buildings at ground level, pumped cool dry air into these work areas.

This dehumidified air also provided a means of drying the plaster and brick walls found in these sub-basements.
These materials are very porous and became saturated with the contaminated river water. As an additional benefit to the drying of the walls, this air also minimized the growth of mildew and other micro-organisms.

These micro-organisms not only could grow in the basement areas but also could be transported throughout the building’s duct work. If this should occur the building will become a “sick building” and the time/cost of returning the personnel to work would be lengthened.

Since the water depth in the basements reached up to 40 feet (several basement levels) the majority of the building support equipment was completely under water.

The air conditioners, boilers, pumps, motors, air handling equipment, ballast cables for elevators, electrical switch gear, etc. were all submerged.

As the pumps removed the bulk water from the basements, the dehumidified air assisted in the drying of the various components of the air handling equipment. Rust formation and mildew growth were minimized.

Thus, in a shorter period of time repair personnel could more accurately determine what could be saved and what had to be replaced.


“Because of the drying and environmental control capabilities of the refrigerated dehumidification equipment, the building repairs were accelerated and much of the building was brought on line ahead of schedule,” stated Roger Massey of Enviro-Air Control Corporation.

At the time of the writing of this report, there are still some buildings that have not initiated any “drying out” procedures.

These buildings are in jeopardy of truly having serious moisture and mildew problems because of the increasing temperatures in Chicago. The evaluation and assessment of the need of dehumidification equipment in the above ground floors has not been made.

It is likely that additional drying requirements might be needed. Items such as air and air duct cleanliness, computer terminals and contacts, building contents (papers, furniture, merchandise, etc.) might be saved/dried by the use of this type of equipment.

Charles H. Wyatt is Vice President, Marketing for Enviro-Air Control Corporation, a Houston-based manufacturer and lessor of refrigerated dehumidification equipment used to dry out wet buildings, enclosed structures and contents, and other wet materials.

This article adapted from Vol. 5 #3.

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