22 February 2005

 

Terri Davis

Rapid City Public Library

610 Quincy Street

Rapid City, SD  57701-3665

 

RE:                  Rapid City Public Library – Acoustical Mitigation Design

Attachment

 

Dear Ms. Davis:

 

Thank you for sending the plans and photos for review.  The acoustical problem appears to be a combination of the barrel ceiling and the opening in the 2nd floor to the 1st floor below.  Your sketches of proposed treatment were not entirely clear, but they appear to be typical treatments used in some reverberant spaces.  Our approach is to recommend solutions that minimize impacts on the aesthetics of the space, which depends upon the sources and receiving areas of noise and the intervening paths for noise propagation.  If noise between the floors is the major problem, extensive treatment of the barrel ceiling may not be needed.  An evaluation of the space with some reverberation measurements and computer modeling will help determine where and what type of material may be most cost effective.  Possible solutions may be treatment similar to what has been recommended, treatment of concrete surfaces with absorption material, transparent baffles, treatment of the lobby area, etc.  I would prefer not to make any judgments on what would be most cost-effective and have the least visual impact, until we can evaluate the space.

 

While we have completed similar studies in the past without a site visit, the complexity of the design would suggest that a short visit to Rapid City would be appropriate.  Our proposed work scope is outlined below.  These tasks build upon previous tasks and have proven to be an effective approach to analyzing problems and proposing solutions.

 

1.0

 

 

Project orientation/arrange site visit

This task will include a further examination of the plans, possible materials, and arrangements for a site visit to the Library

2.0

 

 

Travel to and from Rapid City

This task covers travel to and from Rapid City, and reflects some reduction on hourly rate for travel.

3.0

 

 

 

Site visit, measurements, discussions

A library visit, measurement of selected reverberation times, and discussions with library staff are envisaged, to help more clearly and accurately identify the problem(s) to be addressed.

4.0

 

 

Data download and analysis

Any data taken during the site visit will be downloaded into a computer and analyzed to provide information for the following assessment.


 

5.0

 

 

Set up simple room computer model

A room computer model will be set up to evaluate reverberation times and reflections for assisting with material type, amount and placement.

6.0

 

 

 

Analyze alternative treatment

The model will be used to evaluate alternative material types, amounts, and placement on walls, cross beams, ceilings.  Panels or transparent barriers may also be considered if appropriate.

7.0

 

 

 

Review options with library staff (and architect?)

Options for treatment will be reviewed with library staff and if appropriate, the architect, and the most feasible alternatives identified.  It is anticipated that no additional trip will be needed for this review.

8.0

 

 

Memo with recommendations

A memorandum with recommendations will be prepared and submitted.  No detailed engineering or architectural drawings are included in this scope.

9.0

 

 

Follow up questions and specifications

Some time is allocated for follow-up questions relative to recommendations, material specification, and identification of sources.

10.0

 

Administrative

This task provides limited time for project administration and computer support.

 

 

A table of work tasks, estimated level of effort based upon our current understanding of the project, and estimated cost is attached.  Based upon the proposed tasks and level of effort needed to complete the tasks we propose to complete the study for a not-to-exceed fee of $5,300.  Any work requested beyond this scope will require a supplemental agreement.

 

Please let me know if you have any questions and we look forward to assisting you with this project.  A signed and returned copy of this letter will provide us with authorization to proceed with the study. 

 

Sincerely,                                                                                 Agreed to by

                             __________________________

David Braslau                                                                          for Rapid City Public Library

President

                                                                                                _________________________

                                                                                                Date