City of Lafayette Staff Presentation For: Planning Commission By: Christine Sinnette, Senior Planner Meeting Date: March 19, 2012 Subject: PROPOSED TOWN CENTER III STORY POLES Presentation on the proposal by KB Home for erecting story poles for the 81- unit Town Center III condominium project (pending applications SPA01-10, RZ01-11, DR10-11). At the February 21, 2012 Planning Commission meeting, staff and KB Home presented a proposal for an alternative to traditional story poles for the Town Center III condominium project. Traditional story poles would be difficult and unsafe to install due to the constrained site, current active use, and size and height of the project so KB Home proposed an alternative using commercial grade balloons with pennant tape. The Commission reviewed the proposal and asked KB Home to provide the following: More information on traditional wood and metal story pole installation; Information on how the building perimeter, corners, and rooflines would be marked; Information on how floors or plate heights would be marked; Where the balloons would be placed, how they would be tied together to indicate mass, and how they would be anchored; and Consideration of a longer period for the display such as 3-4 days. As requested by the Commission, KB Home has provided a revised report with information about how the building perimeter, corners and rooflines would be marked. Exhibits have been provided showing where the balloons will be placed and how they will be tied together and anchored, how varying roof heights will be shown, and how traditional story pole guy wires would be laid out. In addition to the story poles, photo-simulations submitted with the application will also be used. A sample photo-simulation is attached to this report. STAFF RECOMMENDATION: Approve the proposed story pole alternative. ATTACHMENTS Town Center Phase III Vicinity Map Preliminary Site Plan Story Pole Proposal, KB Home, revised March 15, 2012 Sample Photo-Simulation Comment Letter from Tarja Martin
Transcript
City of Lafayette Staff Presentation
For: Planning Commission By: Christine Sinnette, Senior Planner Meeting Date: March 19, 2012 Subject: PROPOSED TOWN CENTER III STORY POLES
Presentation on the proposal by KB Home for erecting story poles for the 81-unit Town Center III condominium project (pending applications SPA01-10, RZ01-11, DR10-11).
At the February 21, 2012 Planning Commission meeting, staff and KB Home presented a proposal for an alternative to traditional story poles for the Town Center III condominium project. Traditional story poles would be difficult and unsafe to install due to the constrained site, current active use, and size and height of the project so KB Home proposed an alternative using commercial grade balloons with pennant tape. The Commission reviewed the proposal and asked KB Home to provide the following:
More information on traditional wood and metal story pole installation;
Information on how the building perimeter, corners, and rooflines would be marked;
Information on how floors or plate heights would be marked;
Where the balloons would be placed, how they would be tied together to indicate mass, and how they would be anchored; and
Consideration of a longer period for the display such as 3-4 days. As requested by the Commission, KB Home has provided a revised report with information about how the building perimeter, corners and rooflines would be marked. Exhibits have been provided showing where the balloons will be placed and how they will be tied together and anchored, how varying roof heights will be shown, and how traditional story pole guy wires would be laid out. In addition to the story poles, photo-simulations submitted with the application will also be used. A sample photo-simulation is attached to this report. STAFF RECOMMENDATION: Approve the proposed story pole alternative.
ATTACHMENTS Town Center Phase III Vicinity Map Preliminary Site Plan Story Pole Proposal, KB Home, revised March 15, 2012 Sample Photo-Simulation Comment Letter from Tarja Martin
March 15, 2012 City of Lafayette - Christine Sinnette 3675 Mt. Diablo Blvd., Suite 210 Lafayette, CA 94549 SUBJECT: Story Pole Proposal - Revised RE: Lafayette Town Center, Phase III Dear Christine, Please accept this revised proposal for an alternate method of story poles. We previously presented this alternate story pole method to the Planning Commission on February 21st, and have revised this proposal based upon their input. This proposal still includes the use of commercial grade balloons and certified photo-simulations. Using both balloons and certified photo-simulations, KB Home can demonstrate the height, mass and scale of the proposed project. Background (This section remains unchanged) During the last year KB Home and the City of Lafayette have been working to complete the CEQA analysis for Lafayette Town Center Phase III. With the CEQA analysis nearing completion, KB Home desires to begin the public hearing process. However, prior to having the first meeting with the Design Review Commission, KB Home has been asked to provide story poles to demonstrate the height of the proposed condominium building. After researching how to erect traditional story poles, KB Home has determined that traditional methods are both unsafe and impractical for Town Center Phase III. In light of its findings, KB Home requests the City of Lafayette to consider an alternate method of illustrating the project’s height, mass and scale. Using a combination of commercial grade balloons with pennant tape as well as certified computer generated photo-simulations, KB Home will illustrate the height, mass and scale of the proposed project in a way that is safe and practical. Traditional Story Poles Traditionally story poles are used to demonstrate the height, mass and scale of a planned structure by erecting temporary story poles at key locations along the perimeter of the building. Commensurate with the overall height of the story poles, a series of guy wires are used to support each story pole, which requires clear, open space around the story pole area.
Traditional Story Pole Method In conjunction with story poles, pennant tape is attached to the story poles to illustrate the building’s plate lines and/or rooflines. As shown in the example below, traditional story poles are placed along the perimeter of the building and pennant tape is used to mark the plate lines and roof ridges.
Example of a Story Pole Layout Traditional story polling can be used to illustrate height, mass and scale when there is sufficient open space around the site to accommodate the necessary guy wires and clear zones for a safe demonstration. However, because the proposed project is surrounded by developed parcels on all sides, traditional story poles would not be safe. KB Home worked with the project architect, Heller-Manus, to find construction companies experienced in erecting story poles for the type of project proposed. Only one company, Swinerton, had ever erected 5-stories of story poles using wood, but it was in an open area and on a hillside. After reviewing the Town Center III site plan, a representative from Swinerton replied to KB Home by saying, “I do not see how we can do it with conventional wood story
poles.” KB Home additionally researched erecting steel story poles instead of wood, with Harris and Sloan Consulting Group, Inc (Structural Engineering Consultants). The problems of guying the story poles and having sufficient safe zones with steel versus wood story poles still persist. As shown in Attachments 1 and 2, guy wires would need to be provided every 90 degrees around the central story pole, and secured to imbedded concrete footings to support the poles. Because story poles are not permanent structures, a clear fall zone should be planned. The fall zone needed for steel story poles would encroach upon adjacent parcels as shown on Attachment 1, indicating there is insufficient fall zone area for steel story poles. Traditional story poles either wooden or steel, are neither safe nor practical for the Town Center III project location. They would create unnecessary risk to the general public and surrounding properties. As a result of this risk, KB Home proposes an alternate story pole solution using balloons. Proposal Given the constraints of the project site to erect traditional story poles, KB Home proposes to demonstrate the height of the highest rooflines with the use of commercial grade balloons and pennant tape. In addition, KB Home has created certified photo-simulations, with views of the south, east and north elevations to illustrate the height, mass and scale of the project from other vantage points. Balloons KB Home consulted with the project Architect, Civil Engineer and a company called Air Play Events to create an alternate story pole solution involving commercial grade balloons. The balloons will be 3’ – 5’ in diameter and hold enough helium to support stabilizing lines and pennant tape. The balloons will be placed at surveyed locations and raised to a specific height, as labeled in Attachments, 3, 4, 5 and 6, to demonstrate the project’s north, south and east rooflines. As necessary, balloons will be raised between these defined points to support pennant tape. Generally the balloons will be stabilized with one center line and three auxiliary lines secured to sand bags and/or water-filled barrels as shown in Attachment 7. The key difference between the stabilizing lines for the balloons and the guy wires of story poles is that stabilizing lines are not necessary for structural support. That said, they can be safely moved around the site to accommodate existing conditions. The building footprint, as depicted by the green perimeter line on Attachment 3, will be marked with chalk on the project site. To reinforce the building footprint on the south elevation, KB
Home will raise 10’ tall scaffold at the building corners and string pennant tape between the scaffolds. KB Home proposes to execute the story pole demonstration over a three-day period, beginning on a Friday and ending on a Sunday. Tentatively, KB Home would like to perform this task on March 30th through April 1st. If weather conditions prohibit the primary dates, KB Home has identified April 6th through April 8th as alternate dates. The proposed week and weekend days will limit the impact to patrons who use this lot for overflow BART parking during the work week. Additionally, KB Home will ensure the demonstration is conducted during calm weather conditions. On March 26th, KB Home will check the weather and wind forecast from the Lafayette – Happy Valley weather station, to confirm clear conditions with winds of 5-mph or less. KB Home will again verify weather and wind conditions 24-hours prior to the scheduled date, and notify the City of Lafayette that the demonstration will or will not take place. Security KB Home will secure the story pole site with a 24-hr guard during the demonstration to prevent tampering with the display. Certified Photo-simulations During the CEQA review, KB Home submitted photo-simulations of the north, south and east perspectives to the City of Lafayette that were created using computer modeling software. These photo-simulations were forwarded to a third party reviewer, the Planning Center I DC&E (DC&E), and certified for accuracy. KB Home proposes to use these certified photo-simulations as additional exhibits to demonstrate the height, mass and scale of the project in relation to adjacent parcels. Certified photo-simulations will be reproduced on 24” x 36” corrugated plastic and attached to the existing chain link fence for the public to view. In summary, KB Home requests approval of the revised, alternate story pole method described above. With the use of balloons and certified photo-simulations, KB Home can overcome the various obstacles of conventional story polling on the Lafayette Town Center Phase III site. For any questions or comments, please contact Jed Bennett at (925) 750-1749. Very Respectfully, Jed Bennett KB Home, Forward Planner
ATTACHMENT 1
STORY POLE GUY WIRE LAYOUT
ATTACHMENT 2
STORY POLE SCHEMATIC
ATTACHMENT 3
BALLOON LAYOUT EXHIBIT
ATTACHMENT 4
SOUTH ELEVATION
ATTACHMENT 5
EAST ELEVATION
ATTACHMENT 6
NORTH ELEVATION
Balloon
Anchor lines
ATTACHMENT 7
Balloon Anchoring Diagram
Center anchor line Heights are shown on Attachment 1
