1 3 0 E a s t R a n d o l p h , S u i t e 3 1 0 0 , C h i c a g o I L 6 0 6 0 1 3 1 2 . 6 3 3 . 2 9 0 0 s n h - a . c o m July 02, 2021
Sonia Navas , Program Manager
Sheehan Nagle Hartray Architects
130 East Randolph Street, Suite 3100
Chicago , Illinois 60601
Re: 2805 Bowers Avenue Proposed Project – Issue for PCC Review Dear Planning Clearance Committee ,
The project located at 2805 Bowers Avenue is one (4) story building totaling 244,068 square feet being built in two phases. The proposed site encompasses approximately 5.12 acres. The property is zoned ML -Light Industrial zoning. Currently existing on the site, is an approximately 55,000 square foot two-story office building and associat ed paved surface parking and loading dock. The existing building construction consists of concrete and stucco. The building facade consists of mission style stucco archways with sloping tile roof. The proposed project would demolish the existing two-story office building.
The main entrance to the BDC building will be located on Bowers Avenue near the intersection at Mead Street on the western portion of the property, with a secondary entrance also on Bowers Avenue near the northwest corner of the site. The property is irregularly shaped and is bound to the north by an existing one- story office building, to the east by a material testing laboratory and a one-story office building to the South by an existing Silicon Valley Power (SVP) substation (Uranium Subst ation) and the west by Bowers Avenue. The closest residential uses are to the southwest across the existing Union Pacific CalTrain railroad right-of-way.
In addition to the enclosed drawing set and report, the following narrative summarizes key project d esign elements.
Narrative summary of key design elements :
Reduction of the sound levels has been a critical aspect in the design development of this project. The mechanical plants consists of (42) air -cooled chillers with NoiseBlock stacks on top of a building dunnage platform. Each chiller has a self -supported acoustic “chimney” above the condenser fans, to funnel noise up and away from nearby properties . The chimney is also made up of an absorptive material to decrease the overal l energy of the sound produced by the chiller condenser fans. Each chiller is equipped with adiabatic pads for ambient dry bulb suppression during peak temperatures of 80°F DB and above .
In analyzing the sound levels, Air-cooled chillers w/ Noiseblock stacks had the best acoustical performance. In addition to the base mechanical system several different acoustical measures are being incorporated to further reduce the sound as follows:
a. Roof layout was optimized in regard to the dry cooler/chiller orientation for acoustical performance.
b. Air-cooled chillers fitted with noise mitigation packages provided as a factory option. c. Acoustical louver extending to top of chiller fans attached to dunnage platform traveling the full length of the south side of the platform and continuing halfway up the east and west sides of the platform.
2 d. 8-foot-high solid sound barrier wall along the northwest property line measuring 60 feet in length
Other site measures have been added to the project to address acoustical concerns beyond just the mechanical system as follows, all of which are designed to provide a project with the highest possible sound attenuation:
a. The backup generators have been moved to the back of the project (between light industrial properties) to allow the building to create an acoustical block to the surrounding neighbors. b. Back-up generators housed in acoustically enhanced enclosures to reduce noise. c. Louvers extending to the top of chiller fans attached to the dunnage platform traveli ng the full length of the north side of the platform and continuing halfway down the east and west sides of the platform .
d. 15-foot-high sound wall was installed around the substation .
The combination of these different elements will achieve a sound reduction of approximately 10% when compared to code required maximum nighttime level at the nearest residence of 50 dBA. We are continuing to refine these measures with our suppliers and manufactures to further reduce the acoustical properties.
• The project would provide a total of 62 parking spaces on site including 2 accessible and 1 van accessible parking space. Of the 62 on-site parking spaces, 4 spaces will contain EV charging stations and 6 spaces will be reserved for Clean Air vehicles.
• The d ata center building will be approximately 87.5 feet in height to the top of parapet. The mechanical equipment screen on the roof of the building will extend to a height of 10 3.333 feet from the top of the ground floor slab. The building will be located in the center of the site and will be set back at a minimum of 58 feet from the side yard to the north (Walsh Avenue), a minimum of 108 feet from the side yard to the west (to the lot line at the public way), a minimum of 142 feet from the side yard to the ea st (adjacent to a non -residential zone), and a minimum of 162 feet from the side yard to the south (adjacent to a non -residential zone ).
Sincerely,
Sonia Navas
Program Manager