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HomeMy WebLinkAboutItem 3.1TOWN OF LOS ALTOS HILLS June 23, 2005 Staff Report to the Planning Commission RE: SITE DEVELOPMENT PERMIT FOR SLOPE ALTERATION AND GRADING POLICY EXCEPTION; LANDS OF WESSBECHER; 11021 MAGDALENA ROAD; FILE #18-05-ZP-SD-GD. FROM: Brian Froelich, Assistant Planner APPROVED BY: Carl Cahill, Planning Director C RECOMMENDATION That the Planning Commission Approve the Grading Policy exception finding that the project may enhance slope stability and improve area drainage. ALTERNATIVE The Planning Commission may choose to deny the Grading Policy exception if it is determined the project applicant has not submitted sufficient evidence to justify the request. This is a joint project application by three property owners. The lead applicant is the Wessbechers. The lead applicant is also currently in the construction stages for a new residence at 11021 Magdalena Road. The new residence, secondary unit, and pool were approved through a Fast Track hearing in September, 2002. The site borders the northern boundary of the Quarry Hills Subdivision and is adjacent to the quarry wall. The quarry wall has slopes that range from 40% to over 100% and has a vertical elevation of over 165 feet at its highest point, which is the proposed area of work. The applicant proposes to remove approximately 675 cubic yards of earth material from the uppermost portion of the quarry wall. The applicant submitted a slope stabilization plan and a geotechnical report to the Town for review. CODE REQUIREMENTS This proposal requires Planning Commission review because the 675 cubic yard excavation will result in a grading cut of 11 feet, which exceeds the Town's Grading Policy maximum of four (4) feet. i( Planning Commission [ands of Wmbecher June 23, 2005 Page 2 DISCUSSION Grading Data Maximum Proposed Cut 4' 11' Fill 3' 0 Total Cubic Yards 1,000 675 Visibility and Views The proposed grading cut would enhance the views of the Wessbecher property toward the quarry and to the northwestern hillsides and ridgelines in the area. Photo #1 illustrates the existing view from the ground level of the Wessbecher residence currently under construction. Conversely, the Wessbecher home would become more visible from the residents of the quarry and possibly existing homes along Stonebrook Drive and Northcrest Lane. Slow Stability Photo NI (approximate cut) The applicant's geotechnical consultant, Jo Crosby & Associates, has submitted geotechnical findings related to the proposed grading operation. In their review they have included findings from previous geotechnical evaluations of the quarry wall associated with the Quarry Hills Subdivision. These reports are dated from the late 1980's to the early 1990's. Jo Crosby & Associates outline that concerns were raised in those reports about the long term stability of the quarry wall and the weathered greenstone slopes. They document the presence of talus (sloping rock masses) slopes due to spalling (flaking and chipping) of the greenstone along the quarry face and that landslide features were mapped in a report prepared by Harlan Tait Associates in 1991. "In summary, it is our opinion that the proposed grading along this segment of the property would not have an adverse effect on the long term stability of the slopes of the general area. There is potential for slope instability in this area even with grading improvements. According to the reports reviewed, if such slide features were to develop, they would be relatively shallow and impact an area 20 to 30 -feet from the quarry face. If such features do occur, they can be promptly mitigated by slope stabilization methods. The grading in itself will cause some surficial disturbance of the slopes and the removal of existing vegetation. A soil erosion plan should be implemented to include hydro seeding and protection of the slopes with hay, or the use of other means of erosion reduction." —Jo Crosby & Associates October 12, 2004 Planning Commission Lands of Wessbwher June 23, 2005 Page 3 In review of this project the conclusion of the Town's geotechnical consultant, Cotton, Shires, & Associates, is as follows: "We concur with Jo Crosby and associates that the proposed grading would not negatively impact the stability of the slopes, provided that adequate drainage and erosion control measures are implemented. We also agree with the previous Nielson Geotechnical conclusion that the proposed residence does not appear to be at significant risk with respect to potential quarry rim instability; however, potential failure of the existing quarry rim (over time) could reduce the distance between the residence and brink of the quarry rim. Proposed project grading will result in some reduction of earth material loading, in this isolated area at the top of the quarry rim, and thereby could help to reduce the scale of future quarry rim failures. We do not have geotechnical objections to the proposed grading as long as appropriate measures are added to the current grading plan to properly control surface drainage." —Cotton, Shires, & Associates March 1, 2005 Drainage Currently, drainage in the area of proposed grading is characterized by sheet flow to the north and northeast down an unpaved access road toward the lands of Neary-Vidovich. The Jo Crosby & Associates report raises concerns that rain water concentrated on this unpaved road may filter into pre-existing ground cracks in the rock and further weaken the quarry wall increasing the potential for a slide. With the proposed plan the drainage from this area would be redirected back onto the Wessbecher property and into onsite drainage installations. If the project is approved, staff has included a condition that a revised drainage plan be reviewed prior to any grading. Erosion Control The area of proposed grading is currently vegetated with sparse, low growing vegetation. If the project is approved, the Town's engineer has included a condition that an erosion and sediment control plan be submitted and reviewed by engineering staff and the operations must comply with NPDES standards. Conclusion Based on the submitted geotechnical analysis and the Town Geologist report, the project may enhance slope stability. According to the Town Geologist, the proposed residence is not at significant risk with respect to potential quarry rim instability. The proposed grading operation may improve the drainage in the area and reduce the severity of potential slides. The immediate benefit, however, for the property owner would be enhanced views toward the Quarry Hills Subdivision and up to the hillsides and ridgelines to the northwest. Planning Commission Lands of Wessbeche, June 23, 2005 Page 4 ATTACHMENTS 1. Recommended conditions of approval 2. Town of Los Altos Hills Grading Policy 3. Jo Crosby & Associates letter October 12, 2004 4. Cotton, Shires & Associates letter March 1, 2005. 5. Guiliani & Kull grading plans April 13, 2005 (Commission only) cc: Uwe and Beth Wessbecher 11021 Magdalena Road Los Altos Hills, CA 94024 Planning Commission lands of Wcnbmher June 23, 2005 Page 5 ATTACHMENT 1 RECOMMENDED CONDITIONS FOR SITE DEVELOPMENT PERMIT AND GRADING POLICY EXCEPTION LANDS OF WESSBECHER, 11021 MAGDALENA ROAD File #18-05-ZP-SD-GD A. PLANNING DEPARTMENT: I. Prior to final inspection of the residence and the grading project, additional landscaping for this area shall be installed by the applicants to restore areas disturbed by grading. 2. Prior to beginning any grading operation or demolition, all significant trees are to be fenced at the drip line. The fencing shall be of a material and structure (chain-link fencing) to clearly delineate the drip line. Town staff must inspect the fencing and the trees to be fenced prior to commencement of grading. The property owner shall call for said inspection at least three days in advance of the inspection. The fence must remain throughout the course of construction and grading. No storage of equipment, vehicles, or debris shall be allowed within the drip lines of the fenced trees. 3. An updated project grading and drainage plan shall be prepared that depicts the properly controlled conveyance of surface drainage (formerly conveyed along an unpaved roadway alignment along the quarry rim) in a south to north direction through the area of proposed grading. No new surface flow shall be directed over the quarry rim. Drainage improvements in the Quarry Hills Subdivision common area shall be designed for low maintenance requirements. A revised plan shall be submitted to the Town, for review by the Town Engineer, prior to issuance of grading permits. 4. The geotechnical consultant shall review and approve all geotechnical aspects of the project grading plans (i.e., site preparation and grading, and site drainage improvements) to ensure that their recommendations have been properly incorporated. The consultant shall specifically address the proposed drainage design and locations of drainage discharge locations in terms of minimizing adverse impacts to the slope stability. The results of the Geotechnical Plan Review shall be summarized by the geotechnical consultant in a letter and submitted to the Town Engineer prior to issuance of grading permits. 5. The geotechnical consultant shall inspect, test (as needed), and approve all geotechnical aspects of the project construction. The inspections shall Planning Commission Lands of Wesshecher June 23, 2005 Page 6 include, but not necessarily be limited to: site preparation and grading, and site surface drainage improvements. The presence of anticipated earth material properties shall be confirmed. The results of these inspections shall be described by the geotechnical consultant in a letter and submitted to the Town Engineer for review prior to final inspection. I el�:iRf fIS 77 cl 7 h [H e7:17\ ;71 Yu t alp Y YI 6. Final grading shall be inspected by the Engineering Department and any deficiencies corrected to the satisfaction of the Engineering Department prior to final inspection. A final letter shall be submitted from the project engineer stating that the grading was constructed in conformance with the approved plan prior to final inspection. 7. Any, and all, changes to the approved grading plan shall first be approved by the Town Engineering Department. No grading shall take place during the grading moratorium (November I to April 1) except with prior approval from the City Engineer. 8. Two copies of an erosion and sediment control plan shall be submitted for review and approval by the Engineering Department prior to issuance of grading permit. The contractor and the property owner shall comply with all appropriate requirements of the Town's NPDES permit relative to grading and erosion/sediment control. All areas on the site that have the native soil disturbed shall be protected for erosion control during the rainy season and shall be replanted prior to final inspection. 9. The property owner shall inform the Town of any damage and shall repair any damage caused by the construction of the project to pathways, private driveways, and public and private roadways, prior to final inspection and shall provide the Town with photographs of the existing conditions of the roadways and pathways prior to issuance of grading permit. 10. Two copies of a grading and construction operation plan shall be submitted by the property owner for review and approval by the City Engineer and Planning Director prior to issuance of grading permit. The grading/construction operation plan shall address truck traffic issues regarding dust, noise, and vehicular and pedestrian traffic safety on Magdalena Road and surrounding roadways; placement of sanitary facilities; parking for construction vehicles; and parking for construction personnel. 11. The property owner shall pay a roadway impact fee to the Town prior to issuance of grading permit. Three cost estimates from the contractors will be submitted to the Town for review. The cost estimates must include all Planning Commission [ands of Wessbecher June 23, 2005 Page 7 cost associate with the grading, hauling the soil, and dumping the soil to an appropriate site. Upon completion of the grading, a final inspection shall be required to be set with the Planning and Engineering Departments. CONDITION NUMBERS 2, 3, 4, 8, 9, 10, AND 11 SHALL BE COMPLETED AND SIGNED OFF BY THE PLANNING DIRECTOR AND THE CITY ENGINEER PRIOR TO ISSUANCE OF THE GRADING PERMIT. NOTE: The Site Development permit is valid for one year from the approval date (until June 23, 2006). All required grading permits must be obtained within that year. LOSAfLTOS HILLS ATTACHMENT z GRADING POLICY `1 CALIFORNIA Code Sections Section 10-2.7020 of the Site Development Ordinance states that: "The amount of grading, excavation, or fill shall be the minimum necessary to accommodate proposed structures, unless grading is proposed to lower the profile of buildings." Section 10- 2.703(a) requires: "Type 11 foundations — step -on -contour, daylight, pole foundations, or a combination thereof — shall be used on building sites with natural slopes in excess of fourteen percent (14%)." Intent: The purpose of this policy is to outline desired criteria for grading which assure that construction retains the existing contours and basic landform of the site to the greatest extent feasible. It is also intended that the policy provide guidance for "stepping" structures down sloped hillsides, and emphasizes cut to lower the profile of structures over fill or foundation walls, which tend to raise the profile of the structure. While balanced cut and fill is desirable to minimize import or export of soil, to or from a site, it is recognized that the Town's policies and the guidelines below may encourage export as cut is generally preferred over fill. These policies are intended to be used by staff in evaluation and making recommendations to the Planning Commission and/or City Council regarding site development applications, and as guidance for applicants. Individual sites may dictate a need to deviate from the criteria, to the extent permitted by the Planning Commission and/or City Council. 26379 Fremont Road Los Altos Hills California 94022 650/941-7222 Fax 650/941-3160 Policy Re: Grading page 2 Policies: 1. Cuts and fills in excess of the following levels generally will be considered excessive and contrary to Town ordinances and policies to grade only to the minimum extent necessary to accommodate structures and to site structures consistent with slope contours, i.e., "step down" the hill*: Cut Fill House 8'** 3' Accessory Bldg. 4' 3' Tennis Court 6' 3' Pool 4'*** 3' Driveways 4' 3' Other (decks, yards) 4' 3' * Combined depths of cut plus fill for development other than the main residence should be limited to 6 feet, except that for tennis courts cut plus fill may be permitted up to a maximum of 8 feet. ** Excludes basements meeting Code definition. *** Excludes excavation for pool. 2. The height of the lowest finished floor(s) of a structure should generally not be set in excess of three (3) feet above the existing grade, to assure that structures step with the slope. 3. Driveway cut may be increased up to a maximum of eight feet (8') for the portion of the driveway or backup area which is adjacent to a garage that has been lowered with a similar amount of cut. 4. Cut and/or fill for drainage shall be limited consistent with the guidelines set forth above for each type of structure, but shall be the minimum grading needed for drainage purposes, as determined by the City Engineer. Approved by City Council: April 2, 1997 FPOM : Jo Crosby n AssoipIatC5 FHOIJE 140. Feb. 04 2005AJTiq.CHMEWT RECEIVED II �. r „ r EOM iw: s (IN;ut nN FEB 1 1 2005 «,,,,�� w ^ter„�• "O°'r""iq'�F�r09S1ALTOSHflLS SINCE 1965 Project 4387A-6 October 12, 2004 Mr. Wessbecher 11021 Magdalena Road Los Altos Hills, California 94022 Subject: Review of Proposed Grading Along the Northwest Property Line as a Part of the Residential Development, 11021 Magdalena Road, Los Altos Hills, Cali- fornia Dear Mr. Wessbecher At your request, we have reviewed the proposed grading along the northwest area of your property captioned above, and provided comment on the planted work. The purpose of our involvement with this phase of the project has been to form a generalized opinion as to the feasibility of the excavations proposed along thissegmentof the project site and the impact of this grading on the slope stability at the residential development. Our work has been completed in accordance with the conditions of our proposal dated September 13, 2004 We have reviewed the following as a part of this work: 1. Grading plan entitled "Slope Stability Plan," prepared by the firm of Giuliani & Kull, Inc., and dated 9/30104. 2. Geotechnical Evaluation, Neary Property, Los Altos Hills, California: Report pre- pared by the firm of Earth Systems Consultants, with a date of June 30, 1989. 3. Geologic and Seismic Study, Quarry Hills Subdivision, Santa Clara County, Califor- nia: Report prepared by Harlan Tait Associates, and dated May 10, 1991... 4. Geotechnical Investigation, Quarry Hills Subdivision, Santa Clara County, Califor- nia: Report prepared by Alan Kropp & Associates, Inc., and dated June 7, 1991. 5. Various letters prepared by Alan Kropp Associates from September 13. 1994, to March 5, 1998, in response to review comments. FINDINGS We understand that it is proposed to cut approximately 650 cubic yards of material along the ridge that parallels the northwest property line. This area is located on the cast rim of a previously operated, open,pit quarry that was reclaimed to form the Quarry Hills FFOI'I : ]o Crosby 9 Associates PHONE NO. . Feb. 04 2005 10:53AM P2 ' ' Project 4397A-6 October 12, 2004 page 2 Subdivision in Los Altos Hills, California. As noted above, various geological and geo- technical hazard studies have been prepared for that subdivision. The main geological concern outlined in these reports pertains to the long term stahility of the near -vertical, weathered -bedrock slopes of the ahandoned, open -pit quarry. The Harlan Tait Associates study identified in detail the geologic structure of the quarry site, and provided detailed geologic maps and cross-sections of various quarry faces. Based on the Harlan 'gait information, the exposed face of the east quarry rim contains bedrock units identified as Franciscan Complex greenstone (KJgs). This same formation was identified as underlying the Wessbecher property. Landslide features have been mapped along this quarry face in the form of rockfall-topple and translational slides. In addition, talus slopes have formed due to surficial rock spalling along the quarry face. It should be noted that the slide features identified on the Harlan Tait maps are relative shallow in this general area. Also of note is the presence of ground cracks mapped along the cast quarry rim, parallel to the quarry face. Alan Kropp & Associates conuncnted on the possibility of grading the slopes back along The east quarry rim adjacent to the Wessbecher and other neighboring properties in their report dated June 7, 1991. Their firm's comments are as follows "We understand that there is a possibility of grading material off the upper portions of the east quarry rim, adjacent to the neighboring houses. The purpose of this would be to provide more level backyards and views for these properties. This would also reduce the height of the quarry walls and consequently improve the stability of the quarry walls somewhat. If proper drainage is maintained in this area, as described above, there should not be any adverse effects from this potential grading option, and a portion of the unstable quarry wall would be eliminated." CONCLUSIONS Our firm is in general agreement with Alan Kropp & Associates comment stated above. In theory, the proposed grading would reduce the height of the quarry walls and improve the stability of these slopes. According to the grading plan, surface drainage presently flows along the existing fire road from south to north and onto the Lands of Neary-Vido- vich. The concern of this drainage location is that water from rain storms is concentrated along the road alignment above and immediately adjoining the quarry face. Such a condi- tion could allow water to filter into fractures within the rock or into pre-existing ground cracks, identified by others, and lead to slope instability. On the other hand, the currently proposed grading will allow some of the water to flow onto properties where it had not flown before and to spread the flow over a larger area which would improve the concern for concentrated drainage infiltration immediately above the cut slope to some degree. In summary, it is our opinion that the proposed grading along this segment of the property would not have an adverse effect on the long-term stability of the slopes of the general area. There is the potential for slope instability in this area even with grading improve- ments. According to the reports reviewed, if such slide features were to develop, they would be relatively shallow and impact an area 20 to 30 -feet from the quarry face. If such JO CROSBY S ASSOCIATES uEu rtc HN i CAL COMs,u. TANrr SINCE 1955 FFON -Jo Crosby @ nssoclate=_. PHONE NO. : Feb. 04 2005 11: 1IPM Pt Project 4387A-6 October 12, 2004 page 3 features do occur, they can be promptly mitigated by slope stabilization methods. The grading in itself will cause some surficial disturbance of the slopes and removal of existing vegetation. A soilerosion plan should be implemented to include hydroseeding and pro- tection of the slopes with hay, or the use of other means of erosion reduction. We wish to thank you for using our firm for this project, and hope that we may be of further service to you. We will be pleased to answer any questions that you might have regarding this consultation letter. Exclusion of Warranties: Our services consist of professional opinion only, derived in accordance with current standards of professional practice. No other warranty is either expressed or implied, Very truly yours, 10 CROSBY & ASSOCIATES /h,A. Stillman C.E.G. 1868 G.157 25 QPpFESS/0/ R o K. Crosby co . GE250 C.E.G. ;:v 357 cs G.E. 250 w E,:p. 9-05 JO CROSEV & ASSOCIATES .Fn RCnm¢m ,.rm.uirary*. SINCE 1965 RECEIVED 0 COTTON, SHIRES & ASSOCIATES, INC. ATTNFwm q CONSULTING ENGINEERS AND GEOLOGISTS rrsrs�ea n[ JOS AITOS 0.11ILS March 1, 2005 L0184 TO: Carl Cahill Planning Director TOWN OF LOS ALTOS HILLS 26379 Fremont Road Los Altos Hills, California 94022 SUBJECT: Geotechnical Peer Review RE: Wessbecher, Grading #18-05-ZP-SD-GD 11021 Magdalena Road At your request, we have completed a geotechnical peer review of the subject application using: Review of Proposed Grading (letter), prepared by Jo Crosby and Associates, dated October 12, 2004; Site Development Plan (1 sheet, 20 -scale), prepared by Giuliani and Kull, Inc., dated November 18,2004; and Slope Stabilization Plan (1 sheet, 10 -scale), prepared by Giuliani and Kull, Inc., dated September 30, 2004. In addition, we have reviewed pertinent maps from our office files and completed a recent site inspection. DISCUSSION The applicant proposes to remove a portion of an existing cut slope on the west side of the property. Proposed grading extends west onto common areas of the adjacent Quarry Hills Subdivision along the top of the quarry rim. According to the referenced documents, proposed cuts will be up to 11 feet (maximum depth) and proposed earthwork quantities include 650 cubic yards of material to be excavated and exported from the site. The proposed grading would bring a portion of the adjacent quarry rim to the elevation of the existing building pad. We understand that the applicant is concerned about slope stability issues potentially impacting the residence currently under construction on the property. In our previous project peer review letter Qune 7, 2002), we indicated concurrence with the Project Geotechnical Consultant's (Nielsen Geotechnical, Inc.) conclusion that the proposed residence was not at significant risk with respect to potential quarry rim instability. The proposed grading area is generally characterized by a steep to precipitous (43 to over 100 percent inclinations) west- north- and east -facing hillslopes. These slopes have been previously graded in association with construction of residences on the site Northern California Office Southern California Office 330 Village Lane 5245 Avenida Encinas • Suite A Los Gatos, CA 95030-7218 Carlsbad, CA 92008-4374 (408) 354-5542 • Fax (408) 354-1852 (760)931-2700 • Fax: (760) 931-1020 e-mail: losgatos@cottonshires.com www.cottonshires.com e-mail: Carlsbad®cottonshires.com Carl Cahill March 1, 2005 Page L0184 and an access road along the top of the quarry. Adjacent to, and downslope of the proposed grading area, previous quarry grading activity resulted in several precipitous to near vertical stepped excavations/benches that extend down to the current water level in the abandoned quarry pit. The individual slopes are ten to fifteen -feet high. The top of the west facing quarry slope is approximately 30 feet west of the property line. Drainage at the site is primarily characterized by sheetflow along the cut slopes, and north -directed, channelized flow along the quarry access road. The property is underlain, at depth, by mapped greenstone bedrock of the Franciscan Complex. Greenstone is exposed in the cut slopes described above. The proposed grading is constrained by precipitous slopes, potentially pre- existing ground cracks, potential landslides within the unstable quarry rim, potential rock fall hazards during project grading, and possible redirection of runoff to potentially unstable slopes. The referenced letter by Jo Crosby and Associates acknowledges similar constraints, and while they conclude that the proposed grading would not have adverse effects on long-term stability of the slopes in the general area, they note that such grading does not guarantee long-term slope stability. However, they cite previous reports indicating that future landsllding may affect areas within 30 feet of the quarry rim, and recommend erosion control measures be implemented. 0 We concur with Jo Crosby and Associates that the proposed grading would not negatively impact the stability of the slopes, provided that adequate drainage and erosion control measures are implemented. We also agree with the previous Nielsen Geotechnical conclusion that the proposed residence does not appear to be at significant risk with respect to potential quarry rim instability; however, potential failure of the existing quarry rim (over time) could reduce the distance between the residence and brink of the quarry rim. Proposed project grading will result in some reduction of earth material loading, in this isolated area at the top of the quarry rim, and thereby could help to reduce the scale of future quarry rim failures. We do not have geotechnical objections to the proposed grading as long as appropriate measures are added to the current grading plan to properly control surface drainages We recommend that the following conditions be attached to the application: Updated Grading and Drainage Plan - An updated project grading and drainage plan should be prepared that depicts properly controlled conveyance of surface drainage (formerly conveyed along an unpaved roadway alignment along the quarry rim) in a south to north direction through the area of proposed grading. No new surface flow should be directed over the quarry rim. Drainage improvements in the Quarry Hills Subdivision common area should be designed for low maintenance requirements. A revised plan should be submitted to the Town, for review by the Town Engineer, prior to issuance of permits for project construction. 2. Geotechnical Plan Review- The applicant's geotechnical consultant should review and approve all geotechnical aspects of the project grading plans (i.e., site preparation and grading, and site drainage improvements) to ensure that COTTON, SHIRES & ASSOCIATES, INC. Carl Cahill Page 3 March 1, 2005 L0184 thew recommendations have been properly incorporated. The consultant should specifically address the proposed drainage design and locations of drainage discharge locations in terms of minimizing adverse impacts to slope stability. The results of the Geotechnical Plan Review should be summarized by the geotechnical consultant in a letter and submitted to the Town Engineer prior to issuance of permits for project construction. 3. Geotechnical Field Inspection - The geotechnical consultant should inspect, test (as needed), and approve all geotechnical aspects of the project construction. The inspections should include, but not necessarily be limited to: site preparation and grading, and site surface drainage improvements. The presence of anticipated earth material properties should be confirmed. The results of these inspections should be described by the geotechnical consultant in a letter and submitted to the Town Engineer for review prior to final (as -built) project approval. LIMITATIONS This review has been performed to provide technical advice to assist the Town with discretionary permit decisions. Our services have been limited to review of the documents previously identified, and a visual review of the property. Our opinions and conclusions are made in accordance with generally accepted principles and practices of the geotechnical profession. This warranty is in lieu of all other warranties, either expressed or implied. POS:TS:RR:st Respectfully submitted, COTTON, SHIRES AND ASSOCIATES, INC. TOWN GEOTECHNICAL CONSULTANT Ted Sayre Su ervismg Engineering Geologist CEG-) 7995 atrick O. Shires Principal Geotechnical Engineer GE 770 COTTON, SHIRES & ASSOCIATES, INC.