HomeMy WebLinkAboutPettygrove's 1st Block 18 Lot 1 - Addendum to a Geotechnical Engineering Investigation - 1999.10.06.BEK ENGINEERING & ENVIROI\MENTAL, INC.BELLINGTTfu\{
C[VIL . CEOTECHMCAL r ENVIRONMENTAL
October 6,1999
Williams, LLC.
P.O- Box 408
PortTownsend, WA 98368
Re:Report Addendum - Geotechnical Engineering fnvestigation
Lot 1, Block 18 Pettygroves First Addition
Maple Street
Port Townsend, Washington
\ Atrr:Williams' Representative :
BEK Engineering, Inc. presents this letter of addendum to.our July 28, 1999 Geotechnical Engineering
Investigation report- The purpose of the report is to address concems raised by Judy Surber, Senior Planner
with the Cily of Port Townsend. Those concerns include pistol-grip-shaped stumps that Ms. Surber
observed on site and the Cilr requirement that the minimum lot size requirement is 9,900 square feet in
critical slope areas.
A representative of BEK Engineering made a site visit with Ms. Surber (9-15-99) to observe the trees in
question. Two 6-inch red cedar trees were observed with pistol-grip:shaped stumps on Lot 2,
*i,i"h is adjacent to the proposed building site- The tees exhibited pistol-grip shapes only at the base of the
tnrnh indicating that they stabilized foliowing their frst few years of life. The upper tree on the slope was
pistol-grip-shaped in an uphill direction, possibly due to a iimb or some other materiai that laid atop the tee
during its early years that forced the tee to grow horizontally r.nrtii the weight was removed. Based on ow
site observations and soil test pit explorations, it is our opinion that neither of the pistol-grip-shaped tees are
due to unstable soils.
Cfitical slopes are dgfined as extending 10 feet above and below slope sections that are greater than 40-
percent @nvironmentally Sensitive Areas Ordinance Section 19.05.20.55 and Ordinance 2688, February,
1999). As a result the buiiding area of Lot 1 lies within a Critical Area and is therefore an environmentally
sensitive area.
The requirement that buildable lots with critical slopes be raised to 9,900 square feet from 5,000 square feet
may have merit where the areal extent of the residence is a significant percentage of the lol as is typical in
current residential conskuction- The proposed building for Lot t has a 600 square foot footprint with an 810
sqwre foot roof area (2-foot eaves) and approximateiy 100 square feet of pathway. No driveway wili be
constructed. As a resul! the proposed impervious area is less than 20 percent of tre lot- In additiorl, the
developer intends to collect approximately one-third of the roof runoff (3,275 gallons, based on an average
armual rainfall of 19-46 inches from Port Townsend rainfall records for the previous 50 years). The
remaining two-thirds will be released to a combination detention chamber/spreader bench below the
residence
CONCLUSIONS
It is our opinion that the 9,900 square foot minimum lot size is not necessary for the proposed developmen!
providcd that the building footprint is resticted as described above and iroof runoff is handled in a
responsible rnanner.
360{76-9589
80GE59_5597FAX 360{76-{625
2I3E HUMBOLDTSTREET.BELLINGI{AI{,WA 98225
iJts
October 6,1999
Report Addendum - Geotechnicar Engineering Investigation (Williams LLC., Lot r
Ii\DEMNIFICATION AND LIMITATIONS
This report has been prepared to aid in the development of the site from a geotechnical engineering
standpoint. Our site observations indicate surface conditions at the dates and locations indicated. It is not
warranted to assurne that they are representative of conditions at other locations and times. The conclusions
and recornmendations contained in ttris report are based on surface and subsurface conditions observed
during our site visit We assume that the conditions observed are representative of the subsurface conditions
throughout the property. Il during further site developmen! different conditions from those described in
this report are observed or appear to be present in excavations, we must be advised promptly so that we can
review these conditions and reconsider and/or modiff our. conclusions and recommendations where
necessary.
The earthwork contractor is responsible to perform all work in conformance with all applicable
WISHA/OSIIA regulations. There are inherent risks associated with construction on or adjacent to steep
slopes that the contractor and owner must assume. This report is intended to reduce, but not eliminate,
uncertainty regarding the stability of the slope-
We appreciate the opportunity to be of service to you. Should you have any questions concerning this report
or require further information, piease contact Bob Bailey at our office at (360)-676-9589, or toll-free at
(800)-859-sse7.
Sincerely,
BEK ENGINEERING,
)
P RJ\
Thomas
Civil
RB:bb
P.E-, Principal
ExPrR€s 11121/1fu
Robert P. Bailey, M.S.C.E., P.E.
Geotechnical Engineer
2BEKENGINEERING,INC.PROJECT:99161