HomeMy WebLinkAboutEmergency Activity Response- Severe Erosion - BLD Letters / Memos - 12/17/2007 �t+Q`9oN CO
MASON COUNTY
DEPARTMENT OF COMMUNITY DEVELOPMENT
Mason County Bldg. III, 426 West Cedar Street
PO Box 186, Shelton, WA 98584
1854 www.co.mason.wa.us (360)427-9670 Belfair(360)275-4467 Elma (360)482-5269
EMERGENCY ACTIVITY RESPONSE
December 17, 2007
Pearson and Martha Hillius
P.O. Box 1740
Belfair, WA 98528-1740
RE: Landslide Activity Response
Site Address: 1543 NE Old Belfair Hwy., Belfair, WA
Project Description: Storm activity
Parcel No.: 12320-12-01020
To Whom It May Concern:
A site inspection was conducted on December 12, 2007 due to activity caused by
overwhelming rainfall activity on December 3, 2007.
Inspectors noted that this site experienced severe erosion. As a result, the land has
eroded out from under the concrete abutments that support the bridge that is used to access
your property and is considered a dangerous structure.
Pursuant to Mason County Code, Title 14 Building and Construction, permits are required
prior construction under the 2006 International Building Code. If you intend to rebuild or
stabilize the bridge, a structural engineer design must be submitted with a building application.
Additional permits may also be required due to Planning requirements.
If you should have any questions regarding this notification, please contact me at
(360) 427-9670 ext 356.
Sincerely,
JWM*1ftPU)
Mindi Brock
Building Inspector/Code Enforcement
Cc: Property File
January 10, 2008
To: Pete& Marti Hillius
From: Mike Dully
Subject: Private Bridge Abutment on Parcel No.: 12320-12-01020
Reference: Mason County Emergency Activity Response dated December 17, 2007
We have reviewed the reference Emergency Activity Response, the bridge and the
abutments. We found the following:
1. The County has copies of the original engineering drawings for the Subject
Bridge and abutments. The owner advises that the bridge is over Kristina Creek.
2. During the"overwhelming rainfall activity" on December 3, 2007 the volume of
water in the Creek reached a few inches below the bottom of the steel girders that
support the deck of the bridge.
3. On the east end of the bridge the water eroded, or undercut the soil supporting the
east bridge abutment by approximately one foot across the creek side of the
abutment.
4. The soil supporting the west abutment was not eroded during this rainfall event.
5. The superstructure (steel girders deck, trend, and curb boards) and anchorage to
the abutments do not appear to have suffered any structural distress. Therefore,
we did not conduct any analysis of the superstructure of the bridge.
6. Using the loads that are shown on the original engineering drawings we calculated
the soil bearing pressure on the reduced area under the east abutment. This
calculation indicates that the soil bearing pressure, when the bridge is subjected to
the 42.0 kip live load, plus the dead load of the superstructure and the abutments
would be 1400 PSF. The 2006 IBC, Table 1804.2 indicates that a Silty Gravel
soil is OK for 2000 PSF. Therefore, the bridge and abutment should be fully
satisfactory to handle the loads that the bridge was designed for.
If nothing is done to the east abutment the creek will continue to remove or erode the soil
from below the abutment and eventually the abutment will not be able to support the
loads that the bridge was designed for. To reduce the erosion potential we recommend the
following improvements which are described on drawing S-1, which is attached:
1. Fill the void under the east abutment with concrete.
2. Protect the creek side of both abutments, for 5 feet up and downstream from the
bridge and 1 foot above the base of the abutments with 1 and 2 man rocks.
Michael W. Dully, P.E.
MWD Consultants
221 NE Landon Road
Belfair, WA 98528
Phone: (360) 275-5906
E-Mail: mikedully@wavecable.com
PLANNING DEPARTMENT STORM EMERGENCY LOG FORM
Date/time: 1 /1 f0 g Rcv'd byi�Lt Area planner:
/ f l 1 v`A
Owner Name: 4- � 'iu S
Other contact(contractor etc):
1Cc � L4 ':� . Z1 5
Phone number:
Site address: �Cv� 3 _ o B t-r i _ /
Mailing address:
Parcel No. `Z� LU - 2.- O (� — LV��04A jcL
Emergency situation:
I(S"Ve v0 LV ide X I-L' ovx
Conversation outcome, notes:
WDFW-Emergency HPA? Yn
Permit and mitigation follow-up:
Referral information:
�< W FW freshwater contact: Gloria Rogers 360.249.4628 x249
WDFW saltwater contact: Margie Schirato 360.427.2179, Cell 360.791.9818
Ecology Floodplain Management: Kevin Farrell: 360.407.7253