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Home My WebLink AboutGeoTech Report for FPA2002-00004 - FPA Reports - 5/1/2002 MASON COUNTY PUBLIC WORKS DIRECTORICOUNTY ROAD ENGINEER Shekon.Wnhioon 98584 INTER-DEPARTMENTAL COMMUNICATIONS DATE:_ May 1 S`, 2002 TO: Michael MacSems, DCD - Planner FROM: Alan A. Tahja, P/W- Co. Hydr. Engr. WO#PLG-02 SUBJ: _Geo-Tech Report Review NAME: Broughton near Lakeland Village FPA2002-0 004 Michael, The materials prepared for the Rylan Broughton FPA Class IV conversion have been received and reviewed by Public Works. I have also been in contact with Rylan Broughton who provided additional details of proposed Best Management Practices to be implemented in development of the property in conjunction with the timber harvest, and a site plan. Mr. Broughton indicated he had no immediate plans for development of the property after the timber harvest, but is planning to eventually site a single family residence on the property(s). I feel the submitted materials are adequate to allow the timber harvest to proceed, if the recommendations in the engineer's report are followed, and the owner implements the BMPs proposed in his materials. The engineer has indicated no cutting within 15' of the top of the slopes exceeding 28' (approximately 2 horizontal to 1 vertical slopes). This recommendation should be made a condition for approval of the proposed timber harvest. The site plan submitted by the owner indicates a proposed homesite located more than 50 feet back from the top of the steep slopes on the property, which, given the information in the engineer's report, is an acceptable location. In summary, I feel the submitted materials adequately address stability issues pertaining to this property, and the owner should be allowed to proceed as conditioned. Please feel free to contact me at County extension 461 if you have any questions regarding these comments, or if you feel any features need further discussion or attention. ;Si rely, l ?l let Al A. Tahja File: H:\WP\GEO\REVIEWS\Broughton.doc MASON COUNTY PUBLIC WORKS DIRECTORICOUNTY ROAD ENGINEER Shehok Washington 98594 INTER-DEPARTMENTAL COMMUNICATIONS DATE: May 1 S`, 2002 TO: Michael MacSems, DCD - Planner FROM: Alan A. Tahja, P/W- Co. Hydr. Engr. WO# PLG-02 SUBJ: Geo-Tech Report Review NAME: Broughton near Lakeland Village FPA2002-00004 Michael, The materials prepared for the Rylan Broughton FPA Class IV conversion have been received and reviewed by Public Works. I have also been in contact with Rylan Broughton who provided additional details of proposed Best Management Practices to be implemented in development of the property in conjunction with the timber harvest, and a site plan. Mr. Broughton indicated he had no immediate plans for development of the property after the timber harvest, but is planning to eventually site a single family residence on the property(s). I feel the submitted materials are adequate to allow the timber harvest to proceed, if the recommendations in the engineer's report are followed, and the owner implements the BMPs proposed in his materials. The engineer has indicated no cutting within 15' of the top of the slopes exceeding 28' (approximately 2 horizontal to 1 vertical slopes). This recommendation should be made a condition for approval of the proposed timber harvest. The site plan submitted by the owner indicates a proposed homesite located more than 50 feet back from the top of the steep slopes on the property, which, given the information in the engineer's report, is an acceptable location. In summary, I feel the submitted materials adequately address stability issues pertaining to this property, and the owner should be allowed to proceed as conditioned. Please feel free to contact me at County extension 461 if you have any questions regarding these comments, or if you feel any features need further discussion or attention. ;Si rely, llet AI A. Tahja File: H:\WP\GEO\REVIEWS\Broughton.doc ONSOLIDATED ENGINEERING - CIVIL - STRUCTURAL - SOILS - PLANNING - April 3, 2002 MASON COUNTY DEPT. OF COMMUNITY DEVELOPMENT Mason County Bldg. I, 411 N. 5th P. 0. Box 279 Shelton, WA 98528 RE: Rylan Broughton, Timber Harvest Geo-technical Report Dear Sirs: REFERENCE MASON COUNTY RESOURCE ORDINANCE, P. 47, AS FOLLOWS: E. GEO-TECHNICAL REPORT 1- Applicability a) Some slopes are greater than 40%, therefor, a geo-technical re- port is required. b) No slides were observed---This is a geo-technical report. c) Not applicable d) Not applicable 2- No waiver is requested. 3- Qualifications of Preparer as a GEO-TECHNICAL HAZARDS SPECIALIST (See Encl. 1) 5- (2) See typical profile sketch, enclosed, herein. (3) Hand-dug test holes were opened near the steep slopes. Soil found was 6 inches of forest humous underlain by sandy-silty till. (4) See sketch of slope and set-backs for cutting timber. (5) The slope stability of these parcels is excellent as determined by our viewing and photographing vertical tree trunks through- out parcels. (6, 7, 8, 9 & 10) Not applicable NOTE: A setback of 15 feet is required for slopes steeper than 25° for har- vesting trees. P.O. Box 2321 • Bremerton, WA 98310 • (360) 479-5598 9 Fax (360) 377-1376 MASON COUNTY DEPT. OF COMMUNITY DEVELOPMENT Page 2 April 3, 2002 STORMWATER SITE PLAN: There will be little change as the removal of trees will improve growing conditions for ground cover and thus further restrict water flow. The Coastal Zone Atlas of Washington shows no chartered areas of slope instability, nearby. Yours truly, n / 6 B 0s of wA ,.,,yo'S R. B. Bough , P. E. GEO-TECHNICAL ENGINEER Q� 0008913 �4 Encl. 1- Qualifications of R. B. Boughan as a: S 9, 1s o G GEO-TECHNICAL HAZARDS SPECIALIST ONAL. 3 2- Legal Description of Property EXPIRSS '—, cc: Rylan Broughton tl•� /9 2 /via-♦s- fl0 �3s.�. st/•ct -joo.00, 3S. /3 - sao.sr 220.00 30 2 3Se./3 O 0 0 d O � o 0 41 - _ o =- 0 o ,v ems- SS- z 3 Ar d r S.07 Ac. y f•07 A.. ^ o V � o i - I s3s.SL ?34.f1 3.4 Ir.O / h r vo—a," O e -- ---__30 22 -- Z7ZS•J/ DESCRIPTION rn r, At /1 TIT "elf 1:' 7 "( , tut i.wimLAsi -u.RCTEF lc ENE :.nwvw roe /A A/ CONSOLIDATED ENGINEERING --- - OF SHEET NO. �_ P.O. Box 2321 - — / BREMERTON, WASHINGTON 98310 CALCULATED BY ' " DATE�� (360) 479-5598 CHECKED BY DATE SCALE 1 ' Via.s, o '♦ ENGINEERING �� S4L1 ��TED CIVIL - STRUCTURAL - SOILS - PLANNING - ROLLA B. BOUGHAN, P. E. - GEO-TECHNICAL HAZARDS SPECIALIST I, Rolla B. Boughan, am a qualified geo-technical engineer licensed as a civil engineer in the state of Washington with a minimum of twenty years' experience in land slide evaluation. The city of Portland, Oregon, adopted a Landslide Potential Evaluation Form which I, as an experienced geo-technical civil engineer, used in inspecting steep and soil hazardous property for construction. Previously, I had been heavily experienced in designing retaining walls and soils revetments. At Purdue University, where I graduated as a civil engineer, I worked as a student assistant in the soils testing laboratory and took courses in soils and geology. I have performed many geo-technical investigations and written reports on soil hazards for construction in Kitsap, Jefferson and Mason Counties during the past few years. Our firm has worked with other civil engineer geologists on recent projects with excellent coordination and good overall results with references available from these other professiona As a pile foundation design engineer, I am very experienced and much in demand and have excellent references from jobs recently completed. I am a member of the Pile Foundation Institute. CO Rolla B. Bougha P. E. GEO-TECHNICAL HAZARDS SPECIALIST EXPIRES P.O. Box 2321 • Bremerton, WA 98310 • (206) 479-5598 • FAX (206) 377-7556 JOB 'EMK/V ,E GY/C� -1T,07 A i CONSOLIDATED ENGINEERING - of P.O. Box 2321 SHEET rio. 4�L- BREMERTON, WASHINGTON 98310 CALCULATED BY DATE (360) 479-5598 ' CHECKED BY DATE SCALE PO i407 CU7 7r/�/C.aL S�l-1:5 s � 7 (,cJIINrN � i /- "' 4 rl SA)T o �+nr, ri��s.p.siren ps�gook CONSOLIDATED ENGINE ERING - CIVIL - STRUCTURAL - SOILS - PLANNING - April 12, 2002 MASON COUNTY DEPARTMENT OF COMMUNITY DEVELOPMENT Mason County Building I, 411 N. 5th St. P. 0. Box 279 Shelton, WA 98528 ATTN: Michael MacSems, Planning RE: Rylan.Broughton, Timber Harvest and Access Road Geo-technical Report Dear Mr. MacSems: Reference is made to your letter of April .5th, subject as above. REFERENCE MASON COUNTY RESOURCE ORDINANCE, P. 47, AS FOLLOWS: E. GEO-TECHNICAL REPORT 5. (1) The parcel containing the timber for harvest consists of ridges and valleys of glacial till deposited at the conclusion of the ice age. Typically, the soils are sand, silt and with gravel, below. Some samples show a trace of silt or clay. The ground water table is located at some depth as determined from the re- cent well-drilling operation. There are no charted landslides in the vicinity of the parcel as published in the Coastal Zone Atlas for Mason County. 5. (2) A sketch of a typical slope and a steep draw is shown on the tract print-out and in my professional opinion, these are adequate for identifying "important development and geologic features". Mr. MacSems, we question your geo-technical capabilities as you're neither a geologist or geo-technical engineer. The engi- neer, Tajha, does not qualify as a professional in these fields, either. We have determined the lack of qualification of Tajha in a complaint to county officials. 5. (3) See "red-marked" test holes on the tract print out. 5. (4) The engineer should read paragraph 5 (2) above before he determines if our "typical slope" cross section is sufficient. PO, Box 2321 • Bremerton, WA 98310 • (360) 479-5598 * Fax (360) 377-1376 • MASON COUNTY DEPARTMENT OF COMMUNITY DEVELOPMENT Page 2. April 12, 2002 5. (5) Static and seismic conditions are controlled by the fairly gentle slopes; timber to be left on slopes and the vertical tree trunks observed. 5. (6) Septic drain field set-backs, compacted fills for residence con- struction and the set-backs from Top-of-Slope for the timber har- vest are appropriate restrictions to assure slope stability. 5. (7) The clearing and grading plan is shown in typical slope sketch, herein. 5. (8) Timber cutting will allow more sunshine into the property which will assist in the growth of ground cover and help protect the slopes from erosion. 5. (9) An analysis of both on-site and off-site impacts of the develop- ment (timber harvesting) is nil. 5. (10) Drainage and erosion control will be considered and practices dur- ing this proposed timber harvest. There will be no significant environmental impact from the harvest. * HAZARDS OF THE LANDSLIDE AREA WILL BE REGARDED IN SUCH A MANNER AS TO PREVENT HARM TO PROPERTY AND PUBLIC HEALTH AND SAVETY, IN MY PROFESS- IONAL OPINION. -Need for Access and Hauling Road- Mr. Broughton's proposed access road to his dwelling site will be roughed-out and used during the timber-harvest. The slope will not exceed 15% and will be accomplished with switch-backs or hair-pin curves. The undersigned civil engineer will inspect the road construction upon final completion for adequacy of the gravel surface and side-ditch drainage. Yours truly, �. S. BO�� w R. B. BoqCiv E. � Registerngineer 0008913 Encls- as listed, April 5th Letter �icq (to SS�o�vAt ENa cc: Rylan Broughton �� K MASON COUNTY DEPARTMENT OF COMMUNITY DEVELOPMENT 1 Planning l Mason County Bldg.1 411 N.5th P.O.Box 279 Shelton,WA 98584 (360) 427-9670 Belfair (360) 275-4467 Elma (360) 482-5269 Seattle (206) 464-6968 R.B. Boughan P.E. Consolidated Engineering P.O. Box 2321 Bremerton, WA 98310 April 5, 2002 Dear Mr. Boughan, Please find enclosed a geo-technical document that you produced and submitted to my office for Mr. Rylan Broughton. I have checked your report for conformity with the criteria for a geo-technical report as described in Mason County Ordinance 17.01.100.E. I have not reviewed for content, only for form. Please return your document to me once you have had a chance to review my comments and make the necessary modifications. Once the form of the geo-technical has been found complete, I will forward the document to the Mason County Engineer to review for content. Your client should be aware that the County Engineer charges $36.50 per hour of review time (payable at the end of review). 5 (1): Your report did not address item 5 (1) which ask for information regarding "a discussion of general geologic conditions, specifications, specific soils types, ground water conditions and history of landslide activity in the vicinity as required for the Geologic Assessment described above." This information is needed to be complete report. 5 (2): Although our engineer will have the final say, I would note that the site plan submitted is vague in regards to identifying "important development and geologic features." 5 (3): Please show the location of your exploratory holes on the site plan. 5 (4): I will let the Engineer decide if your"Typical Slope" cross section is sufficient. 5 (5): Again, I will let the Engineer determine if this description adequately addresses both static and seismic conditions. 5 (6) —(10): These items must be included in any complete geo-technical report submitted in accordance with our ordinance. Additionally, our legal counsel is telling us that we can not accept any geo-technical reports that does not include a statement that the hazards of the landslide area can be y overcome in such a manner as to prevent harm to property and public health and safety. The report must also assure no significant environmental impact. Mr. Broughton called me today and we discussed the scope of his project We discussed that his proposed road will also trigger the need for a geo-tech report and that it would probably be simpler to expand the existing report to address the road cut as well. You might give him a call to see if he wants to authorize increasing the scope of your report. Sincerely, l� Michael Mac Sems FPA Planner cc: Ryland Broughton RECEIVED • APR 2 6 2002 Storm Water Protection NAsm CO.RAMM DEFT. It is my intention to use the natural vegetation and road ditches as a means of storm water protection. The measures that I plan to implement will reduce the impact of storm water on my neighbors and myself. Vegetation Butter A vegetation buffer will remain on the steep slopes of the property to help slow runoff and water contact time to the ground. This buffer will consist of trees, brush, ahnihc and stumps. The trees that are removed in accordance with the GeoTec report will be processed in the woods leaving the limbs to help reduce storm water. Ditches The ditches will have 3"rock, turnouts to redistribute water to the forest floor, and use existing ditches; all of which will slow and reduce storm water runoff. There will be 2 1 R" culverts placed in the new section of the road to prevent erosion and runoff from going onto the neighbors property. �y 1C.V 6 0V�lkl-kV1 RECEIVED Habitat Management Plan APR 2 6 2002 Tax parcel # 12230 76 00020 N Y2, NE y., N y., sec 30, Twn 22 N, Rng 02 W WXN M PLANNING DER This Habitat Management Plan is in response to the landowner's request to selectively harvest timber within the Riparian Management Zone of an unnamed type five stream passing through the property. A field investigation of the site on March 27, 2002 upheld that this could be done with minimal impact on existing habitat conditions and riparian functions. However, certain procedures must be followed to achieve the level of protection necessary to maintain the existing riparian zone. According to Management Recommendations for Washington's Priority Habitats and Species the existing riparian characteristics will be maintained in accordance with this plan. - Wildlife habitat and plant diversity - Plant abundance - Stream cover - Fine sediment stabilization - Surface runoff retention - Present and future I " recruitment To maintain existing wildlife habitat quality, management practices should result in no measurable impact on existing plant diversity and abundance. The plant species occurring in this riparian zone are Western Red Cedar Thuja plicata, Douglas Fir Pseudotsauga menziesti, Red alder Alnus rubra, Pacific Madrona Arbutus menziesii, Vine maple Acer circinatum, Salal Gautheria shallon, and Evergreen Huckleberry Vaccinium ovatum. Maintaining this plant diversity congruent with forest practices involves minimizing the impact on the surrounding habitat (edge effect). These impacts could include changes in soil temperature, runoff, and nutrient cycling, all of which can affect wildlife habitat and plant diversity. To sustain the existing habitat conditions, timber will be selectively harvested at levels that will minimize this effect. It is recommended that only fifteen percent of the mature conifer be taken based on the field investigation of the site, completed on March, 27, 2002. This recommendation has been agreed upon by the landowners and will be upheld as part of this management plan. The remaining eighty five percent of the mature conifer will be left intact as well as all other plant species in the riparian zone. Tree removal has been documented to destabilize fine sediment causing unnatural levels of recruitment to aquatic systems. The fine sediment recruitment will be minimized to no measurable impact by taking the following actions. Because root structures of stumps are known to provide structural bank stability for 30-60 years, four feet of the remaining stumps will be left intact along with the complete root systems. These stumps combined with the remaining 85% intact conifer will maintain a natural level of fine sediment stabilization. No trees will be removed from the RMZ that occur on slopes that exceed gradient recommendations in the geo-technical survey. This includes the downstream fourth of the RMZ on the property. After being cut, the trees will be lifted out of the riparian zone using an excavator. This will minimize disturbance to vegetative and geomorphic structure that would otherwise occur during the removal process. There will be no heavy equipment operated within the riparian management zone. The timber will be strategically fallen so that equipment parked outside the RMZ can reach and lift them out of the zone without disturbing any other natural bank stabilizing components. Culvert Within RMZ There is a preexisting road that runs perpendicular to the drainage, upstream from the defined channel (see enclosed map). This road will be utilized to transport logs from the RMZ and later used as a driveway. The impacts from this road on the seasonal aquatic system are have been and are expected to be negligible. There is an existing twelve-inch culvert that drains into the upstream most section of the defined channel. Because of the expected use of the driveway, an eighteen-inch culvert will be installed in place of the twelve-inch culvert to maintain seasonal runoff patterns to the system. Measures Necessary for Restoration Following the selective harvest described in this plan, there will be no additional activity within the 75-foot riparian management zone besides what is described in this restoration plan. A major component of this management plan is the replanting of harvested species. There will be 21, out of 140, conifer trees removed from the RMZ most of which are cedar. There will be 90 cedar tree seedlings and 30 Doug fir seedlings planted throughout the areas of harvested trees as mitigation. The remaining 85% intact conifer along with planted seedlings will uphold present and future LWD recruitment to this seasonal aquatic system as well as the riparian habitat area. Impact on the overall canopy cover from the harvest activity described in this plan is expected to be minimal. Although the effect is projected to be negligible, vegetation damage may occur within the RMZ during the falling process. Any mortality will be addressed by re-vegetating disturbed areas with pre-existing species. Shrubs will be planted two feet apart to optimize stabilization potential. They will also be placed in a random pattern to mimic natural conditions. The tree seedlings and shrubs will be flagged after planting in order to relocate them for future maintenance. Schedule for Restoration An on site investigation will be conducted following the harvest to assess damage to shrubs and determine the need for shrub plantings. The restoration of the identified area will commence and be completed during the spring of 2002. Forty-five cedars and fifteen Douglas firs will be planted within the RMZ along with native shrubs in disturbed sites. Monitoring Monitoring of the site will begin in the fall of 2002 and maintained on a seasonal basis. The information gathered will provide the following. 1)Condition of reintroduced plant species; 2) the use of the site by wildlife species, 3) any disturbance and its effect on the restoration effort; 4) any corrective measures that may be deemed necessary to provide the desired restoration outcome. This monitoring will be in effect for the duration of three years. The information gathered will be provided in an annual report and submitted to the Director of Mason County Department of Community Development if necessary. Wetland Delineation Wetland delineation followed a routine methodology based upon the Washington State Wetland Identification and Delineation Manual (1997) requiring positive indicators for wetland soil, hydrology, and plants: Wetland hydrology was determined by water conditions in pits; Presence or absence of of hydric soil was determined by soil conditions in pits dug around suspected wetlands. Absence or presence of wetland vegetation was determined through species identification, estimation of dominance and then assignment of wetland indicator status; indicator status was assigned based upon the National List of Plant Species that Occur in Wetlands (1989). Results No Wetlands Two small pockets of seasonal standing water were identified on the north end of the eastern lot. One pocket of water occurs in a man made ditch while the other occurs in a small basin. Neither area is dominated by over 80% of any wetland vegetation. Plant species occurring in these areas Red alder Alnus rubra, Salal Gautheria shallon, and Salmonberry Rubus spectabilis are not endemic to wetland habitat. No hydric soil was found in any pits dug around the suspected wetlands. I trust this information is sufficient for you needs at this time. If you have any questions or recommendations feel free to call. c Lee Boad Biology Consultant PO Box 2854 Belfair Washington 360-620-0618 S Anderson Lake SW F � t _ F i 57 ' 1 � r, I J � I I \ t'. 'r F, �x `' x'• N r I ��• Surveye• Driveway Property corner points roperty boundary lerwood Creel tributaries VSherwood Creek mainstern 4 �• 9. ";i';j' +4i •ia {1'1 i�.,r �,; �l;! .iSection ARoads Contours scale 1:3,500 T/M/N'//' I i