HomeMy WebLinkAbout701344049 Geotech Assessment (2004)O
~ AUen L. Hart Engineering Geotogisfi
1720 Norkh Oakes, Tacoma, Washington 98406
(253} 752-8963
~_
February 3, 2004
Paul Coover
12SS Nancy Court
Upland, CA 91786
Coover Property Summary Letter
Jefferson County, Washington
Tao Parcel #741344049
Project #(3311080
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Al1G 2 12006
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This letter follows our several telephone conversations and letters regarding evaluating and reducing the
existing slope setback recommendations on your Jefferson County property.
As you know, my geotechnical engineering consultant and Y have completed a reconnaissance of the site and
slopes to the east and west, and reviewed readily available geologic information, just as the Stratum Group
says they did to develop the recommended setback in their report for the property dated August 20, 2001.
• However, the difference is in the conclusions, they recommend a 1 SO foot top of slope setback while we
conclude that a lesser setback, on the order of 7S feet, would be appropriate. Therein lays the problem. Using
the same information we have come to greatly differing conclusions based an interpreetation and opinion of
slope conditions. They have published their conclusions and their recommendation is nearly in line with the
Uniform Building Code H/3 {slope height divided by three} standard top of slope setback. Although the
overall slope from the shoreline to the top of slope an your property is roughly 450 to S00 feet which would
develop a setback of ISO to 167 feet; the Stratum Group's recommended 1S0 foot setback is not being out of
Line per UBC if that is the only criteria used. However, it is our opinion that the 1 SO foot setback is excessive
and the slope stability is better than they have assumed.
In order to argue for the shorter setback distance additional information must be providedand/or analysis
done. We had hoped that water well records for the community wells in combination with slope cross
sections would provide the necessary additional information but, as you know, the well logs for the
community wells are not available and the wells themselves are not located adjacent to or at the elevation of
you property as we had been Ied to believe. Additionally, the Washington State Department of Ecology has
no welt logs in the area that are located. at a helpful distance from the site. With regard to slope cross
GEOLOGIC AND GEOTECBNICAL CQNSULTING
Project #0311080
f Over Property, Parcel #70134.4049
February 3, 2004
• Page No. 2
sections, due to slope grades and height rt is not possible to develop cross sections with the detail required for
stability analysis as had been hoped.
Based on discussions with my geotechnieal engineering sub-consultant there appears to be two available
routes to gain the necessary additional information, test drilling or topographic analysis, both of which are
costly.
Test drilling would entail making four or five borings dawn the length of the west-facing slope to depths of
75 to 100 feet, soil sampling, laboratory analysis of the materials encountered, and the development of a
generalized slope section for analysis. A drilling program such as this assumes that desirable drilling
locations can be accessed from existing and/or new roads and the down slope property owners will allow
road construction and explorations on their property, which is generally nrrt the case. Roughly the cost of a
drilling and tasting program such as this could be in the range of about $24,000,00 to $28,000.00 or more. It
is our opinion that a drilling program would not be acost-effective use of your money and would provide
minimal information regarding scope stability as a large portion of the baring depth would be in landslide
debris, the stability of which is not of real concern.
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Based on our study it is our opinion that the best way to proce~ is with a topographic analysis of the site and
adjacent slopes combined with additional reconnaissance, spring and seep location, and geologic mapping.
The cost of this type of study would be on the order of $3300.00 to $3,800.00 plus the cost of the topographic
map at a scale usable for the study. We have reduced the area of needed mapping from the origina180 acres
to 60 acres and attached is a revised quotation from Green Mountain GeoServices far development of the
topographic map covering the area.
Because of the lack of additional information needed to provide a basis for developing an argument far a
reduced top of slope setback and our inability to complete the services outlined in my proposal to you dated
Uctober 14, 2003, I am terminating our services to you at this time. To try to proceed without this needed
additional information and develop a meaningful argument for a lesser setback would be a waste of time and
money as we are still in the realm of interpretation and opinion only. With regard to billing for services to
date, in that I do not feel that I personally have aided you to any great extent I am not charging for any of the
time I have spent on the project, i.e., original meeting and site visit with your son, site reconnaissance time,
data search, and air photo review. Similarly, I am not billing for the eight hours my geotechnical engineering
• consultant has spent in travel, reconnaissance, and discussions with me.
Allen L. Hart Engineering Geologist {253) 752-8963
Projcet #0311080
Coover Property, Parcel #701344049
February 3, 2004
. Page Na. 3
As you consider your options with regard to the property, please feel free to call me with questions. It
remains my opinion that the parcel can be developer for residential use and the major hurdle to moving
forward with the development is the report by the Stratum Group and the lack of newJadditional information.
Sincerely,
Allen L. Hart, RG/CEG, CPG
Licensed Engineering Geologist
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Alka L. Hart Ent(1'ia~ria~ Geologist (253) 752-8963
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