Warehouse Repair and Restoration Project Zorges Incorporated

Lake Charles, Louisiana

When Hurricane Laura went through Lake Charles, Louisiana, one of the buildings that was damaged and flooded was the primary warehouse (Warehouse A) for Zorges Incorporated. Zorges is a leader in the synthetic fiber spinning business and also a major employer for the city. Other manufacturing facilities went through the hurricane with only moderate damage from wind and minimal flooding. Warehouse A was the building that was especially damaged by flooding. It is critical for Zorges to get this warehouse dried out and operational as soon as possible. Warehouse A is an older building, and therefore the design allowed for more flooding. The management at Zorges has hired your company, Building Science Systems Incorporated (BSSI) to get the warehouse dried out, repaired and fully functional. When it is working again, Warehouse A provides full climate control for manufactured products. This includes complete temperature and humidity controls within 5% of the required set points for the manufactured fiber products. (Skovitz Engineering)

The dimensions of Warehouse A are: 150 x 75. After the flooding, Zorges removed all of the contents from the warehouse. Realizing that the damage was more than expected, they hired Skovitz Engineering, Lake Charles, to assess the damage, evaluate the structural integrity of the building and suggest strategies for getting the building back in service as soon as possible. The quick summary of the engineering report was that the structure was acceptable, some wiring changes were needed, but the big problem was drying things out! Skovitz estimates that a layer of 3 deep water has penetrated into the concrete and sublayer of gravel. Due to saturation of the water table below, most of the drying will be from the top of the concrete slab. Their calculations suggest that 10% will dry around the perimeter and by seeping into the ground below. The remaining 90% will need to be dried by moisture movement up and out of the slab.

One suggestion for drying the slab has been to let the warm weather in Lake Charles dry out the slab naturally. The theory, is that with temperatures averaging in the upper 80s (and humidity averaging ~ 80%), the slab will only need a bunch of fans to carry all of this moisture away. Your first task is to explain to the accounts-payable manager at Zorges (who is promoting this, economic, approach), why the natural approach will not work for expedited drying. You will want to provide a general explanation of psychrometrics for this argument.

The next step is to set up three industrial dehumidifiers within Warehouse A. Water collected from these dehumidifiers is collected and drained to the outside storm sewer. Here is the information about each of the DH units:

• DH Unit 1 duct entering the unit is 8 x 10; the air velocity going through the unit is 55 feet per minute. Over the first ten days of operation, the entering air conditions are: 85 dry bulb temperature and 90% RH and the exiting conditions are: 75 dry bulb temperature and 60% RH. (Assume 13.5 ft³ / pound of dry air)
• DH Unit 2 duct entering the unit is a 10 inside diameter; the air velocity going through the unit is 60 feet per minute. Over the first two weeks of operation, the entering air conditions are: 80 dry bulb temperature and 85% RH and the exiting conditions are: 70 dry bulb temperature and 55% RH. (Assume 13.5 ft³ / pound of dry air)
• DH Unit 3 duct entering the unit is 12 diameter; the air velocity is 75 feet per minute. Over the first fifteen days of operation, the entering air conditions are: 85 dry bulb temperature and 90% RH, and the exiting conditions are: 80F and 50% RH. (Assume 13.5 ft³ / pound of dry air)

Note that given the size and the orientation of Warehouse A, there will be different conditions at each of the locations for DH units 1, 2, and 3. Also, we are assuming that these units are specially manufactured and adapted for BSSI and not like anything that would be available commercially.

For each DH unit, use psychrometric calculations to determine how much water is removed from the warehouse over the designated operating time period. Given the total estimate of the water that will need to be removed, determine the percentage of the total water that each unit has removed.

What do these results tell you about this strategy for expedited drying for Warehouse A?