39 -006 Hockanum Rd Lot 39-006 8-19-16Vreeland Design Associates
An integrative approach to residential design, engineering and site planning
116 River Road, Leyden, MA 01337 Phone: (413) 624-0126
Email: dvreeland@verizon.net Fax: (413) 624-3282
Date: August 19, 2016 To: Louis Hasbrouck Inspector of Buildings/Zoning Enforcement
Northampton, MA 01060
From: David Vreeland, P.E. Vreeland Design Associates
Re: Hockanum Road, Lot 39-006, Northampton, MA: Replacement of existing deteriorated
40’x 64’ steel framed Storage Building with a new 40’x 64’ steel framed building. Dear Louis,
I have been consulting with Dwight Scott, General Construction & Environmental, Inc., about
the replacement of the existing 40’x 64’ badly deteriorated steel framed equipment storage building with a new steel framed building of the same size. See the attached floor plan and cross section. The use group classification is U. The building is located on Lot 39-006 on the east side of Hockanum Road just south of the dike. See the attached Assessors Map. The existing
foundation and anchor bolts appear to be in good condition and adequate for the erection of the
new steel framed building. The lot, as is the entire area south of the dike, is in the flood plain of the Connecticut River. The following is a summary of information for the proposed project: 1. The 100 Year Base Flood Elevation for this section of Hockanum Road is 123.0 feet with
a flood hazard classification zone of A-13. See the attached section of the Flood
Insurance Rate Map. The approximate location of the lot is marked. 2. Based on Northampton city mapping, the ground elevation at the building is 112.0 feet. See the attached section of the USGS Topographic map. The top of the foundation wall is approximately 9”-12” above the ground elevation and the floor slab is 9” down from the
top of the foundation. The grade at the back, east, gable end of the building is
approximately 4’ lower to allow trucks to back up to a loading dock. 3. The enclosed area of the original and proposed 40’x 64’ building is 2,560 sq.ft. In accordance with the 2009 IBC: Section G1001 – Utility and Miscellaneous Group U: G1001.4 Enclosures below design flood elevation: 1. In flood hazard areas not subject to
high-velocity wave action, enclosed areas shall have flood openings to allow for the
automatic inflow and outflow of floodwaters. From the ASCE 24-14 Flood Resistant Design and Construction: Section 2.7 Enclosures Below the Design Flood Elevation: 2.7.2.1 Non-Engineered Openings; the total net open area of all openings shall be at least 1 in2 for each sq.ft. of the gross enclosed area. Openings will be cut into the 2½” thick
metal wall panels on the north and south 64’ eave sides of the building, 12” or less above
the adjacent finish grade. 3”x 3” welded wire mesh will be installed in the openings. Based on a 3/16” diameter wire the 3”x 3” mesh has an 88% open area which will require a total open area = (2560 in2 / 0.88) = 2909 in2. An option that meets this requirement is to install six (6) openings, three (3) on each the north and south sides, with options for
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opening size; 12”x 41” or 14”x 36” or 16¼”x 30”. Other variations are possible as long
as they meet the criteria outlined above. 4. Any mechanical and electrical systems will be installed above the Base Flood Elevation or protected in accordance with 2009 IBC: G1001.6 Protection of mechanical, plumbing and electrical systems.
5. Since the enclosed area of the original building was not vented for flood waters there will
be a potential net gain in terms of flood water storage volume with the new building. Assuming an average grade at the foundation of 112.0’, an enclosed area of 2,560 ft2, and with the base flood elevation = 123.0’, the loss of flood storage volume would have been 123.0’ – 112.0’ = 11’ x 2,560 ft2 = 28,160 ft3 gross volume. Assuming an approximate
volume of 156 ft3 for the thickness of the foundation wall and 450 ft3 for the steel frame
and wall panels, the net loss of flood storage volume for the original building was approximately 28,160 ft3 – 606 ft3 = 27,554 ft3. Since the new building is near identical to the old building in terms of construction details, but with flood openings there will be a potential net gain in storage volume of 27,554 ft3.
Based on my calculations and the attached documentation, the proposed building and existing foundation system appears to be in compliance with 780 CMR: 115:00: G301 Design and Construction Requirements in Flood Hazard Areas and Coastal Dunes and the 2009 IBC: Section G1001.
Please contact me if you have any questions or need additional information. Sincerely,
David Vreeland, PE Vreeland Design Associates