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HomeMy WebLinkAboutHartstene Island Bluffs Tree Removal Site Eval - GEO General - 6/10/2009 ��Obacauoncc*a June 10, 2009 Judith M. Greene 4301 Fairwood Blvd NE Tacoma, WA 98422-4636 RECEIVEDSummary of Site Reconnaissance Nov 2 $ 2Q12 179 Nantucket Road 426 W. CEDAR ST- Mason County, Washington File No. GRE5-01 This letter report summarizes our observations and conclusions relative to geotech-nical conditions in the vicinity of your property located at 179 Nantucket Road, based on our reconnaissance of that property and adjacent areas with you on April 11, 2009. Our services have been provided at your request and in accordance with our services agreement dated April 10, 2009. The subj ect property is located near the north end of Harstene Island in Mason County, Washington, in the southeast portion of the Hartstene Pointe development. The existing duplex within the property is located approximately 40 feet from the top of a steep bluff overlooking Case Inlet. The adjacent bluff is approximately 30 feet high and consists primarily of dense,glacially consolidated sand that predates the most recent glacier to occupy this area, some 15,000 years ago. Along the base of the bluff, very stiff to hard glacial silts are exposed within the lower portion of the bluff face. Near the top of the bluff, there exist patches of the glacial till and recessional outwash from the most recent glaciation. This segment of the shoreline faces toward the east, and has a relatively long eastward "fetch" (the expanse of water across which wind blows toward the shore) and it is therefore subject to active wave erosion. Based on typical erosion rates along Puget Sound shorelines, it is our opinion that the bluff segment adjacent to your property is likely to have a long term bluff retreat rate (averaged over a period of many decades) of between 0.1 and 0.25 foot per year. However, shoreline retreat does not occur at a slow and stead), rate but is episodic. Decades may go by with little or no or no observable changes, followed by one or more landslide events that result in several feet of bluff retreat. The amount of retreat along the top of the bluff that occurs during a single landslide event depends on the style and size of the landslide, but is typically in the range of about 3 to 10 feet. 7030 NE 134th Street Kirkland, Washington 98034 425-821-2015 www.tubbs.com Judith M. Greene June 10, 2009 Page 2 So as not to increase the rate of erosion along the bluff, it is important that uncontrolled surface water not be allowed to drain across the top of the bluff. A corrugated plastic pipe presently conveys stormwater from within your property to the base of the bluff. We recommend that the pipe be replaced with HDPE(High Density Polyethylene) pipe, which is much more resistant to breakage. During our site reconnaissance,you expressed concerns regarding a group of evergreen trees located along the top of the bluff northeast of your residence. The southern three of these trees have not yet been undermined by bluff retreat, but the northern two have been partly undermined, In addition,the northern two trees have intertwined roots such that if one were to fail, it would likely take the other with it. Your concerns were that the trees may take a portion of the adjacent upland area with them if they were to fall or slide down the bluff, or that the trees may fall toward the duplex during a storm blowing from the east, since their eastern roots are partially undermined. As we indicated to you at the time of our site visit,we believe those are both reasonable concerns,though we don't believe either of those issues represent a probable and immediate danger to your property. The tree roots presently provide some reinforcement to the soils near the top of the bluff,but that reinforcement is progressively diminishing as the top of the bluff erodes, and when they fall or slide they will indeed disturb a much larger area of soil than if they were preemptively removed. From the standpoint of slope stability we have no objection to their removal, so long as the root systems are left intact and care is taken to minimize disturbance of areas on and adjacent to the top of the slope. We are not as well qualified to comment on the hazard that the trees represent to the adjacent structures,except to note that it appears to be a reasonable concern, and therefore recommend that the HPMA have their forestry consultant look at the trees and provide and opinion regarding that concern. If the trees are removed, it is our opinion that planting of replacement trees is not necessary from the standpoint of erosion and slope stability, because other large trees presently exist a few yard back from the slope. However, where vegetative gaps exists or will exist along the top of the slope,we suggest that you consider planting brushy vegetation as a barrier to discourage people from too closely approaching the top of the bluff. Native vegetation in that area presently includes evergreen huckleberry,salal and Oregon grape,and these and other brushy vegetation would be suitable. The evergreen huckleberry would probably provide the best barrier, but according to a botanist who reviewed our photographs, 7030 NE 134th Street Kirkland, Washington 98034 425-821-2015 www.tubbs.com Date: July 13, 2009 Subj: Bluff Erosion Adjacent to Island Homes on Nantucket To: Hartstene Point Maintenance Association (HPMA) Board of Directors 202E Pointes Drive East Shelton, WA 98584 p��+ f (t From: Island Homeowners at 177 Nantucket 179 Nantucket 181 Nantucket 183 Nantucket We are enclosing bluff inspection letters recently written by Dr. Tubbs for Judith Greene (179 Nantucket) and William and Mary Ann Andersen (183 Nantucket). As you will see, Dr. Tubbs expresses concerns about possible damage to our homes and to the bluff should identified trees be toppled by wind or further erosion--events he believes are reasonable concerns. We are requesting the Hartstene Point Maintenance Association (HPMA) Board of ' Directors consider removal of the problematic trees on both properties as described by Dr. Tubbs. Please advise. hank you, 1 u ith M. Greene, 179 Nantucket GENERAL CONDITIONS This agreement describes the terms and conditions under which'fubbs Geosciences provides professional services to our clients.and the rights and responsibilities that we and the Client have under this agreemment. COMPENSATION Our compensation will be a lump sum amount if so indicated in the proposal or services agreement.or wil I be determined on the basis of brie and expenses in accordance with the following schedule: Labor Principals $150/hour Senior Scientists and Engineers $120/hour Staff Scientists and Engineers $80/hour Secretaries,Drafters and Technicians $50/hour Contracted professional and technical services will be charged at the applicable hourly rates listed above or at cost plus 10 percent. whichever is greater. Time spent in depositions,trial preparation and court or hearing testimony will be charged at one and one- half times the above rates. Time spent in either local or intercity travel,when travel is in the interest of this contract,will be charged in accordance with the foregoing schedule. Equipment Field and laboratory equipment,per day Ranges from$20.00-250.00 Mileage for vehicle travel,per mile $0.50 Other Charges for services,equipment and facilities not fumished directly by us,and any unusual items of expenses not customarily incurred in our normal operations,arc charged at cost plus 10 percent.This includes shipping charges,subsistence,transportation. printing and reproduction,long distance and cellular charges,miscellaneous supplies and rentals,surveying services.drilling equipment,construction equipment,watercraft,aircraft and special insurance which may be required. Taxes required by local jurisdictions for projects in specific geographic areas will be charged to projects at direct cost. BILLING Billing will be submitted monthly unless otherwise agreed. Payment is due on receipt of the invoice unless otherwise agreed in writing. A service charge of$20 or one percent of the amount due,whichever is greater,per month will be added to unpaid accounts due over 30 days. All expenses incurred in liening or collecting any delinquent amount including,but not limited to,attorneys'fees,witness fees.court costs,and charges at current billing rates for time,transportation and subsistence shall be paid in addition to the delinquent amount. LIMITS OF LIABILITY We strive to perform our professional services with the standard of care and skill of qualified geoscience professionals currently providing similar services under comparable conditions in this geographic area of practice. We do not warrantor guarantee our services. However,should we or any of our professional staff be found to have been negligent in the performance of services to the standard of care of the profession the maximum aggregate amount of the Client's recovery against us or our staff shall be limited to the twice the amount of our fee for our services provided under this agreement. We shall not be liable for consequential damages,including loss of use or loss of profits,or indirect damages. regardless of cause,whether such claim is based on professional or non-professional liability. In the event the Client makes a claim against us.at law or otherwise,for any alleged error,omission or other act arising out of the performance of our professional services.and the Client fails to prove such claim.then the Client shall pay all costs,including attorneys'fees,incurred by us in defending ourselves against the claim. CLIENT FURNISHED INFORMATION The Client is responsible to provide us with a description of the property,its location.and the locations of any underground utilities.facilities or structures on or adjacent to the property that are relevant to our work.The C lient also must advise us ofthc location and nature of any known or suspected hazardous materials that may exist on the property. The Client is responsible for advising us of any requirements for entry or work permits,security clearances,licenses,or any other required permissions. If the property is not owned by the Client,the Client shall obtain right-of-entry for the purpose of accomplishing our services. TERMINATION OF SERVICES In the event that the Client requests termination ofour services prior to completion of a report,we reserve the right to complete such analyses and records as are necessary to place our files in order and,where considered by us necessary to protect our professional reputation,to complete a report on the services performed to date. A termination charge to cover the cost thereof in an amount not to exceed 25 percent of all charges incurred up to the date of the termination of the contract may be made at our discretion. INSTRUMENTS OF SERVICE Reports, field data, laboratory data.analyses,calculations,estimates,designs and other instruments of service shall remain our property. We will retain pertinent records relating to our services for a period of ten years following submission of our report. Copies of the instruments of service will be made available to the Client on request for a reasonable fee. Reuse of any instruments of service by the Client on extensions of this project,or on other projects,or otherwise outside the scope of this agreement,without our written permission will be at Client's risk. Client agrees to defend,indemnity and hold harmless Tubbs Geosciences from any claims,damages and expenses arising from such reuse. 4L Ali 4 Ce#1 .43 oil RD,EL APPROX.MEAN MGM VIDE SOL I NOTE 3 re 3 21' SEE. M2 (M-G), Eau REPLACE,*. a 31. M.0 30"CV IL.. xXom� ACE SDlcr.,DR LE-62 6 a NETR DITC05H(A.) --Yff- LL-10 SEE Now Ir o --vr 64,7* CULVERT TABLE LE. 4.25 a. LL-4&22 cm�m r 2w 12- IS' 3r to Q BERM ACROSS lar 3r dra Le- ]a'LL-104.Or AN EL LF-ft w A AL E 21 w z 0 ul P ur Mo 00 ILM 0 -c W z Lu a I I.PLIL=ES "EAm.=,`",2C" ul 0 > OR �-Z t IMLLMRCUT)WOOLIT w NOT REPLACED. "KKR MM,Na O'WRWAD,APPROX S* ABOW ADC --11 Moo FEET 5 TURAL F o AT AND IN.REOME ADENTIONAL WALE 5 FL . 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Q{E ... .......... .... ::::.::. .^....:.:.:: ..... .. .... E o 3 0 SS S S o� HARTSTENE POINTE e.a DAIE:YAA.3UD9 q p MAINTANANCE ASSOCIATION ,T " //�9.. SCAIE: NOTED Y:AN CpINtt 9A91NCfON - �•� !� 7 W N DRAINAGE IMPROVEMENTS Z AQ' DDA+" A" Cn—Y OYbo�'..,I. MIS CFILAXEWO DETAIL! a<r ALA orcdEO: "S CONSULTING ENGINEERS s rt- Na. AEM90N OAR AA9D APPROVED:N.S 9GTDL�N.9�ND10x Mom'(1AE)>••-ALEA Bill &Mary Ann Anderson MID J U NI 3 0 2009 183 Nantucket Road Shelton, WA 98585 SERVICES AGREEMENT File AND4-01 This confirms the agreement between Bill & Mary Ann Anderson (Client) and Tubbs Geosciences for geotechnical services relative to slope stability conditions at your property located at 183 Nantucket Road in the Hartstene Pointe area of Hartstene Island, Washington. The services provided by Tubbs Geosciences will consist of: 1. Review of published geologic information regarding the subject property and nearby areas, and any information that you may provide regarding drainage issues or slope instability at and near the property. 2. Surface reconnaissance together with you of the subject site and adjacent areas. 3. Discussions with you regarding geologic, hydrologic and other influences that contribute to slope stability within your property,possible impacts of slope stability and bluff retreat on the existing house, and possible means of mitigating those impacts. 4. Additional services that may be requested by you and agreed to by Tubbs Geosciences. The professional services listed above will be provided in accordance with the terms described in the attached General Conditions,which is a part of this agreement. The fee for items 1 through 3 listed above will be a lump sum fee of$150,payable at the time of our site reconnaissance. The fee for additional services including a written report if requested will be determined on a time-and-expense basis using the rates indicated in the General Conditions. Tubbs Geosciences The services described above are authorized by: Donald W.Tubbs 'Authorizing Signature Typed or Printed Name April 10, 2009 ji/' 1 � Date Date ;Individual with contracting authority and responsible for payment of Tubbs Geosciences services. Please Return One Signed Copy of This Agreement For Our Files Attachment 7030 NE 134th Street Kirkland, Washington 98034 425-821-2015 www.tubbs.corn