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Drainage Rpt 001 SAMANTHA RIDGE Drainage and Erosion Control Report Prepared for: Jack Long The One Eleven Building Auburn, WA 98002 (253) 846-5756 December 5, 2007 Prepared by: Pete Swan Reviewed by: Jeff McInnis, PE PETRA ENGINEERING,LLC 535 Dock Street, Suite 213 Tacoma, WA 98402 (253) 752-7617 Project No: 06-036 Project Name: SAMANTHA RIDGE Storm Report -Samantha Ridge.doc ~~`~ :~ETRA ENGINEERING, LLC `-~ r ~~ 1 181021 PHONE (2591752.78171 FqX (259178L8682 I WWW,PETRRQiC.NET s ._ TABLE OF CONTENTS 1. FACILITY SUMMARY FORM ............................................................................... ...................3 11. PROJECT ENGINEER'S CERTIFICATE ............................................................. ...................7 III. DRAINAGE REPORT ............................................................................................ ...................8 Section 1 -Project Description ......................................................................... ................. 8 Section 2 -Existing Conditions ......................................................................... ................. 8 Section 3 - Infltration Rates/Soils Report ......................................................... ................. 8 Section 4 -Wells and Septic Systems .............................................................. ................. 8 Section 5 -Fuel Tanks ...................................................................................... ................. 9 Section 6 -Sub-basin Description .................................................................... ................. 9 Section 7-Analysis of 100-Year Flood ............................................................. ................. 9 Section 8 -Aesthetic Considerations ................................................................ ................. 9 Section 9 -Facility Sizing and Downstream Analysis ....................................... ................. 9 Section 10-Covenants, Dedications, and Easements .................................... ............... 10 Section 11 -Property Owners Association Articles of Incorporation ................ ............... 10 SecOon 12 -Other Permits or Conditions Placed on the Project ...................... ............... 10 Section 13 -Bond Quantities and Declaration of Covenant ............................. ............... 10 N. EROSION CONTROL PLAN ................................................................................ ................ 70 Section 1 -Construction Sequence and Procedure ......................................... ............... 11 Section 2 -Soil Stabilization and Sediment Trapping ...................................... ............... 11 Section 3 -Permanent Erosion Control and Site Restoration .......................... .........._... 12 Section 4-Geotechnical Analysis and Report ................................................. ............... 12 Section 5 -Inspection Sequence ...................................................................... ............... 12 Section 6 -Control of Pollutants other than Sediments .................. _. _........._.. . _.... _...... 12 Section 7 -Utilities .........................._._....._................................_........,.......... ........._..... 12 Appendix A-Vicinity Map, Drainage Exhibits, FEMA Map and LOMA Appendix B -Hydraulic Analysis Appendix C -Geotechnical Report SAMANTHA RIDGE 12.05 C PAGE 2 I. FACILITY SUMMARY FORM Proponent's facility name or identifier (e.g., Pond A): Name of road or street to access facility: Hearings Examiner case number: Development Review Project No. /Bldg. Permit No.: Parcel Number(s): Part 1 - Project Name and Proponent Project name: Project owner: Project contact: Address: Phone: Project proponent (if different): Address: Phone: Project engineer: Firm: Phone number: Detention Pond Crystal Springs Road NW #15854-001-01 22719240600 Samantha Ridge PETRA Engineering 535 Dock Street -Ste. 213 Tacoma, WA 98402 (253) 752-7617 Pete Swan PETRA Engineering (253)752-7617 SAMANTHA RIDGC 12.050] PAGE 3 Part 2 -Proiect Location Section .............. Township .......... Range ............... 19 17 02 w.nen sod eddrxaoa of adiaeenf mm~eM owners[ Floyd Cummings (North) 614 Crystal Springs Rd. Yelm, WA 98597 Pacific Frontier, LLC (East) 406 Crystal Springs Rd. Yelm, WA 98597 Clarke Properties, LLC (South) 404 Railroad Ave SE Yelm, WA 98597 Ryan & Tami Pearson (South) 404 Edwards St. SW Yelm, WA 98597 Troy Troong (South) 402 Edwards St. SW Yelm, WA 98597 '' Michael Killion (West) 15744 Coates Rtl. Yelm, WA 98597 Part 3 -Tvpe of Permit Application Type of permit (e.g., commercial building): Other permits (~): ^ DOF M/ HPA ^ COE Wetlands ^ FEMA ^ Shoreline Management ^ Encroachment ^ Other ^ COE 404 ^ DOE Dam Safety ^ Floodplain ^ Rockery/Retaining Wall ® Grading Other agencies (Federal, Slate, Local, e[c.) that have or will review this Drainage and Erosion Control Plan: None Part 4-Proposed Proiect Description What stream basin is the project in (i.e., Clover): Project Size, acres 4.12 Acres Zoning :........................ R-8 On,site: Residential Subdivision: Number of lots .................. Yelm Creek 29 Units SAMANTHA RINGS 12.0; v PAGE A Lot size (average acres) .................................................... NIA Building PermitlCommercial Plat: Building(s) (footprint, acres) ............................................... 0.44 Acres Concrete paving (acres) ..................................................... 0.28 Acres Gravel surface (acres) ........................................................ NIA Lattice block paving (acres) ................................................ NIA Public roads-Including gravel shoulder (acres)............ 0.25 Acres (off~ite) Prtvate roads-including gravel shoulder (acres)........... 0.33 Acres On-site impervious surface total (acres) ....................... 7.05 Acres Part 5- Pre.develooed Project Site Charecteristlcs: SVeam through site (yln) ..................................... Yes Name ................................................... Yelm Creek Shoreline Designation ......................... Urban Type of feature this facility discharges to (i.e., lake, stream, intermittent stream, pothole, roadside ditch, sheetflow to adjacent property, etc.): Spreader Trench GROUND Swales(yln) ............................................................... N Steep slopes-steeper than 10 % (yln) ........................ N Erosion hazard (y/n)....._ .............._............................ N 100-yearfloodplain(y/n) ............................................ Y Wetlands (y/n) ............................................................ N Seeps/springs (y/n) .................................................... N High groundwater table (y/n) ...................................... N Creek ......................................................................... Y Part 6 -Facility Description Total area tributary to facility including off-site (acres) ..... .............. 4.12 Acres Total on-site area Vibulary to facility (acres) ..................... .............. 4.12 Acres Design impervious area tributary to facility (acres) ........... .............. 1.05 Acres Design landscaped area tributary to facility (acres) .......... .............. 3.07 Acres Design total tributary area to facility (acres) ..................... .............. 4.12 Acres Enter"t" for type of facility: SAMANTHA RIDGE 12.05 Oi PAGE v Wet pond detention ............................................. ....... t Wet pond water surtace area (acres) ................. ....... 0 Dry pond detention ............................................. ....... 0 Underground detention ....................................... ....... 0 Infiltration pond ................................................... ....... 0 Drywell infiltradon ............................................... ........ 0 Coalescing plate separator ................................ ........ 0 Centrifuge separator (VOrtechs 2000) ............... ........ t Other ................................................................. ........ 0 Outlet type (enter "1" for each type present): Filter ......................................................................... .. 0 Oil/water separator .................................................. .. 0 Single orifce ............................................................ .. 0 MulOple orifces ........................................................ .. 0 Weir .......................................................................... .. 0 Spillway .................................................................... .. 0 Pump(s) .................................................................. ... 0 Other (Spreader Trench) ........................................ ... 1 Part 7 -Release to Groundwater Design percolation rate to groundwater (if applicable) ..........................................NIA Part 8 -Release to Surtace Water lif a0olicablel Prior to entering the storm pond, the Flow will be routed through a Vortechs Model 2000 for stormwater treatment. Once through the water quality device and attenuated by the 6,700 cubic foot storm pond, the stormwater will be released to the Yelm Creek system through a spreader trench system located just outside of the 100-year flood plain elevation. _- SAMANTHA RIDGE t2050Z II. PROJECT ENGINEER'S CERTIFICATE I hereby certify that this Drainage and Erosion/Sediment Control Report for the SAMANTH RIDGE project has been prepared by me or under my direct supervision and meets minimum standards of care and expertise which is usual and customary in this community for professional engineers. I understand that City of Yelm does not and will not assume liability for the suffciency, suitability, or pertormance of tlreinage facilhies designed by me. ~~/ ~~ /j Signatur ~~,V K'~ ~ ~q EoF w~ ~ZII I /d 7 ~Fe Date q P ~ x]399 SAMANTHA RIDGE !2.050] PAGE? III. DRAINAGE REPORT Section 7 -Project Description This report accompanies the civil plan submittal for the development of the 29 unit mulit-family project named Samantha Ridge on Crystal Springs Road in Yelm, WA. The site is located east of Crystal Springs Road in the northern extremity of the City of Yelm, directly across from the intersection between Crystal Springs and Coates Street in Section 19 of Township 17N and Range 2E. The project involves the creation of 29 residential units on 8 lots, approximately 14,500 Sq. Ft. of associated private roads, and the associated recreation tracts and open space areas to satisfy the PRD requirements of the City of Yelm. Section 2 -Existing Condffions Appendix Acontains apre-developed hydrology map showing the site as it exists today. As can be seen from that map, the site remains mostly undeveloped and covered in grasses, a small number of trees, and a small residence in the southwest corner of the subject property. The overall site proposed for development is 179,583 Square Feet, or 4.12 Acres, after a rightof-way dedication to the City of Yelm. Although the overall parcel is signifcently larger than 4.12 acres, the westem portion of the site is being segregated through a Boundary Line Adjustment process and sold to a third party. The site is sloped to the east, fairly steeply at the western portion and fairly shallow farther to the east. The site is entirely contributory to the small creek bed known as Yelm Creek. This creek bed has been dry during the duration of this project, but historically has flowed through the rainy season. There is an associated Floodplain to approximately elevation 330 which is noted on the plans submitted with this report. Yelm Creek is wnsidered a Critical Area. A Critical Areas Report has been compiled and submitted by Talasaea Consultants under separate cover. This Critical Areas Report will address the reduction of the CAO buffer to accommodate the proposed design. Section 3 -Infiltration RateslSoils Report A geotechnical report was prepared by Gary A. Flowers, PLLC for this project and is included in Appendix C. This report was prepared only for use by the design engineer in designing pavement and for exploration of the feasibility of on-site infiltration. Section 4 -Wells and Septic Systems Records at Thurston County Health Department and the Department of Ecology were searohed in order to locate wells and septic systems that may be located within the setback distances from the stonnwater pond. In addition, the Project Engineer, or someone under his direct supervision, has visited the site to verify the presence or absence of wells and septic systems as best can be done visually without trespassing onto other properties. All wells and septic systems found to be located within the setback distances from the stormwater pond or ponds have been shown on the plans. SAMANTHA RIDGE 1205 0] PAGE 8 Section 5 -Fuel Tanks Records at Thurston County Health Department and the Department of Ecology were searchetl in order to locate the presence of above and below ground fuel storage tanks that may be located within the setback distances from the stormwater pond or ponds. In addition, the Project Engineer, or someone under his direct supervision, has visited the site to verify the presence or absence of fuel tanks as best can be done visually without trespassing onto other properties. All fuel tanks found to be located within the setback distances from the stormwater pond or ponds have been shown on the plans. Section 6 -Sub-basin Description The site is made up of a single basin with a high elevation of 345 feet along the southwest comer of the site, sloping to the west. Impervious roads, sidewalks, and driveways will be routed to the ponds for treatment and detention. All roofs will be provided with a storm drainage stub connecting to the cenbalized storm tlrainage water quality and detention system, thus eliminating the need for individual infltration systems on each lot. Section 7-Analysis of 100-Year Flood A Hydrogeologic Assessment was prepared by GeoEngineers addressing potential; high groundwater Flood hazard areas on or around the site. This report is was submitted under separate cover. Section 8 -Aesthetic Considerations The stormwater facility will be landscaped. Additional landscaping shall also be provided throughout the project in conformance with the approved landscaping and tree restoration plan, as applicable, and as otherwise required by the approving authority. Section 9 -Facility Sizing and Downstream Analysis In the developed condition, we are proposing the installation of a 22' wide internal road system consisting of approximately 14,500 Sq. Ft. of new impervious. In addition, the building patls will comprise approximately 19,000 square feet of impervious area, with the driveways encompassing approximately 10,700 square feet of impervious area. When tallied, the impervious area created by the project will total 45,738 square feet, or 1.05 acres. The proposed storm drainage system, designed to comply with the 1992 DOE stormwater Management Manual for the Puget Sountl Basin, will include a detention pond at the eastern portion of the project site. This storm pond has been sized to receive mnoff from the site. The developed 2, 10, and 100-year storms have been estimated using the SBUH methodology using the Stormshed® software. The pond was then sized to reduce Flows to the pre-developed Flows of 50 % of the 2-year, and the 10 and 100-year Flowrates. Prior to entering the storm pond, the Flow will be routed through a Vortechs Model 2000 for stormwater treatment. Once through the water quality device and attenuated by the 6,700 cubic foot storm pond, the stormwater will be released to the Yelm Creek system through a spreader trench system located just outside of the 100-year Flood plain elevation. A hydrologic analysis of the developed conditions has been completed using Stormshed software and the SBUH methodology using a Type 1A hyetograph. On-site soil has been classified as Spanaway Recessional Outwash Sand and Gravel as a result of the on-site soil exploration compelled by Gary Flowers, PLLC. Although the SCS mapping and the on-site work by Gary Flowers show the site as containing both Spanaway and McKenna soils, infltration on a large scale is not recommended due to the presence of a high water table. Instead a detention system is proposed. _. __.. SAMANTHA RImGE 12 05 0] PAGE 9 The results of the detention analysis, showing the expected runoff values from the impervious areas contributing to the WO and detention systems, are tabulated below: Event Pre-Develo Flow cts Develo ed Flow cfs Attenuated Flow cfs 2- r/24-hr .1960 50°~-.0980 .6074 .0990 10- r/24-hr .4183 .9366 .4179 100- r/24-hr .6667 1.2448 .6660 The detention pond sizing was performed utilizing the rates presented above and is presented in the Appendix B. The appendix contains the hydrology calculations as well as pre and post-0evelopment maps. Section 10 -Covenants, Dedications, and Easements All stormwater facilities located on private property shall be owned, operated, and maintained by the property owners, their heirs, successors, and assigns. The property owners shall enter into an agreement with the goveming body, a copy of which is included in the Maintenance Plan. The agreement requires maintenance of the stormwater facilities in accordance with the maintenance plan provided and shall grant easement for access to the governing hotly to inspect the slormwater facilities. The agreement also makes provisions for the goveming body to make repairs, after due notice is given to the owners, if repairs are necessary to ensure proper performance of the stormwater system and if the owners fail to make the necessary repairs. The cost of said repairs shall be home by the property owners, their heirs, successors, and assigns. Section 11 -Property Owners Association Articles of Incorporation All residential subdivisions shall form a Homeownefs Association for the purpose of assigning responsibility and liability far the operation and maintenance of stormwater facilities jointly serving lots within the subdivision. The association is not required for facilities that serve a single property owner. Articles of Incorporation shall be developed for the association and submitted to the goveming body prior to foal project approval Section 12 -Other Permits or Conditions Placed on the Project Building Permits will be obtained to construct the buildings. Section 13 -Bond Quantities and Declaration of Covenant These items will be supplied after the first review of this plan set. IV. EROSION CONTROL PLAN __ __ SAMANTHA R~OGE '~~`~~~~ SAGE 10 Section 1 -Construction Sequence and Procedure Prior to commencing any grading or filling upon the site, all erosion control measures, including installation of a stabilized censWCfion entrance, shall be installed in accordance with this plan and the details shown on the drawings. More specifically, the following censWCtion sequence shall be observed: 1. Construction on this site shall be conducted substantially in accordance with the construction sequence described on the plans and in this erosion cenVOl plan. Deviations from this sequence shall be submitted to the project engineer and permitting jurisdiction. Deviations must be approved prior to any site disturbing activity not contained within these plans. 2. For each phase of the development of this site, the following general sequence shall be observed: a. Flag clearing limits. b. Install construction entrance. c. Install inlet protection for existing inlets in the vicinity of areas to 6e disturbed. d. Call for inspection by the project engineer. e. Clear antl grub site per plans and specifcations. f. Install erosion control measures as required. g. Rough Grade site antl install utilities and storm drainage improvements. h. Fine grade and pave site. i. Stabilize site with landscaping and required seeding. j. Remove erosion control measures after site is stabilized and after approval of Pierce County inspector. 3.Once the site is disturbed, continue operations diligently toward completion. 4. Monitor all erosion control facilities, and repair, modify, or enhance as directed or as required. Section 2 -Soil Stabilization and Sediment Trapping Sediment ponds shall be constructed at the beginning of each phase of construction to pertorm as temporary sediment traps. Protection of offsite properties against sedimentation is an absolute necessity. Additional measures may be requiretl to provide full protection of downstream areas. Additional measures may include, but are not limited to, use of sediment bags in existing catch basins, increased filters within sediment ponds such as hay bales, introduction of coagulants to the sediment ponds, and other such measures. Continuous monitoring of the erosion control systems, depending upon site and weather conditions, shall be ongoing throughout project development. Vehicle tracking of mud off-site shall be avoided. Installation of a stabilized construction entrance shall be installed at the start of construction at the exit point to be used by equipment. This entrance is a minimum requirement and may be supplemented if tracking of mud onto public rights-0f-way becomes excessive. If the entrance mat becomes filed with dirt, it will be refurbished by dislodging the riprap and reconstructing the pad. Alternatively, new material will be added to the pad to provitle storage for additional sediment. Should sediment be tracked on to the street, operations will cease until the tracked material has been removed by street sweeping and the pads have been refurbished. Catch basin inserts placed throughout the site will trap sediment and prevent silt laden runoff from leaving the site. The insert will be examined regularly for rips or tears in the material and will be replaced if defects are identifed. _. ____ SAMAMHA RIDGE 120507 PA Er1 Section 3 -Permanent Erosion Control and Slte Restoration There are no permanent retaining walls, energy tlissipaters, geoteztiles, or bank reinforcements associated with this project. This project shall utilize landscaping and paving as permanent erosion and sediment control features. Disturbed areas on and off-site shall be hydroseeded or otherwise landscaped or stabilized upon project completion to provide permanent erosion control where required. Erosion control measures shall remain in place until final site stabilization is imminent (e.g., paving scheduled with a favorable weather forecast). Section 4 - Geotechnical Analysis and Report Existing slopes in the area of the stormwater ponds are at a maximum of 2%. No embankment is required. A geotechnical report has been prepared by Gary Flowers and was submitted under separate cover. Section 5 -Inspection Sequence The Project Engineer, or someone under his direct supervision, and the permit authority shall inspect the temporary erosion control facilities (construction entrance, sediment traps, and erosion control barriers) prior to commencement of construction. During and following construction, the Engineer shall inspect the construction of the permanent stormwater facilities and report to the permit authority his fndings as to pertortnance and operability of the completed system. The plans for this project specify the use of various erosion/sediment control measures: construction entrance and catch basin inlet protection. These sediment control facilities will be inspected weekly at the end of the work week and subsequent to each storm event. Section 6 -Control of Pollutants other than Sediments Control of pollutants other than sediments is the responsibility of the Contractor. As a minimum, a centralized equipment marshalling area and containment area is to be provided on-site for equipment maintenance and storage of any equipment service materials. An area on-site will be selected as a temporary debris and stockpile area for materials that will be removed from the site. Erosion control containment and berming of this area will be provided for pollutant containment and sheeting provided for coverage or lining if applicable. The superintendent will be expected to use his best judgment in addressing any and all conditions that are potentially damaging to the environment. Section 7 -Utilities Trenches will be opened only immediately prior to installation of the sewer and water utilities. Trenches will be backfilled immediately after any required testing or inspections of the installed utility lines. In locations where the utility trenching may interfere with stormwater quantity and quality control measures, the construction superintendent will coordinate the actlvity to ensure that no erosion or sediment transport occurs. Trenching spoils will be Ueated as other disturbed earthwork and measures will be taken to cover or otherwise stabilize the material, as required. SAMANTHA RIO(~E ~2 OS 07 PAGE 12 APPENDIX A -Vicinity Map & Drainage Exhibits SAMANTHA RIDGE 12.05 07 PAGE ~ 3 VICINITY MAP p o > o r Z ~ ~ ~ O CO,q ~ o z ss ~ SRE ~ ~~SF o ~~' ~~ ~q~ 5 F~ a5 ~~ FsT ~o~ ~y~5~` ---- -__ AMANTHA RNGE ~ 12.05 01 PAGE 14 / ~ / ~ / ~ / ~ / ~ ~ / / ~ / ~ / / ~ / ~. r ~, F SAMANTHA RIDGP ~ 2.05 ~] PAGE 15 /~ ~~, / ~ ~ ~ / / ~ / ~ ~/ ~. _.__- SAMANTHA RIDGE X20501 PAGE 16 SAMANTHA RIDGE 12.050] envr ~ DEAR MR. BAKER: This iaiis refumce ro s ueat'tlmt ~c`Federet Emer ."~~ - ~° ~' req gmay Tdehegemem` Agetwy,.iFP.'UtA) determine if the property described in the enclosed dacumem is loeaud wiehin an idmti(kd Special Flood tianN Atp, the era thtl would be iamWated by the Rood having a 1-patent chance of ping equekd m ezeeeded is snq givmr year (base flood}, m the elfeMive Natbnal Flood insmanee Pmgrem (NFIP) vup. fJaiog ~ informatio0 sobRitkd and the etfecnive NF)P map, our detesmimtion is shovm m the attached Leher of Map Amendmem (COMA) Determination Document. This determination document provides additional informaton regarding the effective NFIP map, Ne legal d<scriptiom of Cite property msd om determitWim. AddiliotW documents are enclosed which provitle information regarding the aubjed property and LOMAs. Please see the List of Enclosures below to determine which documents aze enclosed Utlwr sltxhmema apeeiflc ro this request may be irtcloded as rcferenad in she Determination/Cammmt docuttmm. If you Mve any questions about this Imu or any of the erclosures, please contact the FEMA Map Amirtenae Center roll free st (877) 336-2627(877-FEMA MAP) or by iettu addressed ro tlrc Federal Emergency Management Agency, 3601 EiaeMower Avenue, Suite 130, Alexandria, VA 22306ba39. Siercercly, Wi° R~ it- W illiam R. Blanton Ir., CFM, Chief Engimermg Management Section Mhigmien Dimclomte a.18T OF BlaCt,OS VRE3: IA6aA DE3ERhBNAT1OT1lmClfMENT (REMOVAL) ec: 9tatelCOmmonwea0h NFW Coordinamr Community Map RePm~rY Raeion SAMANTFIA RIDGE Federal Emergency Management Agency Washington, D.C. 20472 as s September 11, 2007 MR. DENNIS BAKER CASE NO.: M-10.069DA GEOMATICg LAND SVRVEYMO COMMUNITY: Q'fY OF VELM, THURSTON COUNTY, P.O. 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TNa CecunM »Wa Yw alNtllw NFIP mp h rammv Yn eWN.C propNy Nw We 6FHA bgYB 0n W eINmM KW map'. IM1enlnre. Yu FeOeral maMalay 0aM Inyverva lpWromaM eoea rbt apgy. Ibpeap. Uu YNer Me W oppcn b mnWOa 1M IIOOE Imuerca rpWramaq 10 paled M NxnvN Nk en ab ban. A PrtNnae RW IaYq B'RP)baaaaNbtrewlapbmba gnYpe 0C6FNV Mpmgl4A aMhee PNP Yb RV aw un agNya6rn4.wE. TN QiWmIMBan b bFH an ma aeop aab prnan% anflaMa. TM ancbap pecumanb peWe adlMmal InlgmWOn rpeNNp IMa NMminabx tl yw Nw mY puneen ah0o1 Nh tlawment geaae cenlad iM FEMA Mp Auhbnce CeNer bl Bw al (a]]l a%M2] (6TFEW MAP1 ar ey NBat a0abuaC b tlN Fep»I Fnlwganq MmpNMnl Apenry. Mgt Elaennprer Avsmm. 9oW IaU. AbuMls, vA ]S1Mdeb. W.rG:. R Gl.,r ~ N9MC R. Menbl Jr.. CFM. biaf E^ielee~^N laanapemMHp4m MWaum IYYJaaY SAMANTHA RIDGE 12 05 3] PAGe 20 PapaxefS Dah: ypramEer 11, 200/ Case MO.~OT-f0-089eA LOMA Federal Emergency Management Agency. f WeshinOron,0C.2W12 LETTER OF MAP AMENDMENT DETERMINATION DOCUMENT (REMOVAL) ATTACHMENT 1 ADDITIONAL CONSIDERATIONS t.EGAL PROPERTY DESCRIPTION (CONTINUED) CpiMENCING el the NorMxest Carrrer of the NoAheast Ouartar a/ Me NorMVnlst Duarmr; Merca SO1 °02M°E. 192207 teak MerKO SOi°Oi'S8'E. 1095.58 feet Mena S01°02'00"E, 192.08 feet ro Me POINT OF 9'!NWG; NeMe6N37{{'~,IIc'dilA1d1a4G~N01'02'00RYib8!1:~re0G' 8A7 f0at tllmlce Sx8'07'43•E. 47.n het Rrcnm 983°2552"E, 7d.19 het Nance N83`54'13"E, 74.48 feet MBrice N80.49'37°E. 29.92 het inence 88S°48'10"E, 21.70 feet Oamm S37°14'31'E, 58.02 hat Merox S98°14T72"E, 31.58 bat Iharze 894.10'2CE, 47.18 bh1; Ihenca S30°OS'02"E, 48.72 feat IMrwe &38.22'25'E. 98.87 bet BfenC0S51.31"d8"E, 47.M bel; 8lenca S49°13'i5°E. 23.55 teak tlwnca S07°52'28°W, 34.82 teat; thence 84P45'47E, 78.88 bM; thence 818°3S'74g, 32.010 inence S40°3T04"E, 48,48 feet Merge S35.78'44'E, 27.28 feet tlfence N87°77'28"E, 37.25 feet; Vence S50°59'00'W, 238.78 bet thence N01 °02'00"yV, 10.00 feel; bwnpa s79°4a54w, 700.93 teat tMrre sot°oz•omE, lo.oa f~ Mence sT9°4a•54°w, loo.oo reel b Ma POYPT of eEralNNlwG PORTIONS OF TFPo PROPERTY REMAIN 04 TN6 SFNA Rhb Additlonal CgMiderelbn aPpBae tp iM plepedar9l Prwmlyd PoNOr18 W 90S properly. but not Me sublet of Itre Oeterminafbn/Comment dowmant may rcmaln in Me 9pedN rood NoIIad Arce. Tnercforc, any future canstructlon or substantial improvement on Me property remains atrbleUtp FedEtel,6, end local regulatlone for floodplain rnanagerrw3nt TAb eWdmeM praMU eENawW 1r11MMNlM1 ropGMnp Nn myuaal. n you Mre enY QWOMns suw tlue MMNIMnI, Mme uMM Me IEW Map MW1MU GMM pb kx el (e7?) 9]baa11la7],iEMR MAPI M Ey NMI aaerlEiM b IM GBEm1 EmCrplllry MMpM11YM pMq.3101 FaeemwrAVenue, $14e Ile. NuuMle. VA223pIGle. VMnn~ R BMrMn k.. CFM. Cher EnaMMYq Mmpenae 3etllon MAgelen Wetlm~s SAMAMHA RIDGE 12052 PAGt 21 Federal Emergency Management Agency Weahington, D.C. 20A72 a ADDITIONAL INFORMATION REGARDIIVG LE7"i'ERS OF MAP AMENDMEMC When making detemtinnfioas on requaa fw Letters of Map Amaidmtnt (Lph1Aa), the Department of Hama)aod Seuurity'a Federal fimetgeOCY Managemem ABeacy(F"EMA) basav is duerminartoo on 8¢ flood heaa[d mfonvatiao available at the time of the detemdoation. Requcattrs ahoWd 6e aware that flood $gyUea6raa abet aliould 6e swm WW rattoval o[ a propat7r (parcel of lam w svucllne) from tlx Spcctal Flood flazud Ata (SERA) tnaan FNMA has delarrnirred the property is rto[ subject to immdad~ by the Hood havinga t-perrxnt chance ofbting equaledwa<aded in any given year (base flood). This does rat man Wepropetty is sot subjeIX ro othw flood hazards. The properly coWd be inundated by a flaadwiW a magoim~ lSrater than the bast flood or by tocalimd flooding no[ shosw on the effective Nedaml Flood hsstaaaoc Program (NF[F) map. 1'ha abed of a LDMA i9 is rataoves the Pedasl rerpdrameM tw the lender ro regahe flood inamante myangs$~ dx pmpaty dprn'tied. `Hw LOMA b sot a waiver of dre caoditim that doe propdty owmr tn&imaia paodioamurcecovnageTor the ptupwty. Onfydte.leader an waive We Rood iaaunncepmchase RggjfmxM!>caeuaa the leaden impowd We requbement. the property mwier mart reaarst and receive a wrfnaw swhver from the larder before cancelNg 1hr polity. The 4mder may demrmine, ~ is own sa a buq[readeWeia4 Wet itwiaha m Cont®ae Wo flood inamanceraqubeaunt to proteteia finamiai risk oa du lea TheLIRafAprovi~FEMAk oommat on [hemandatory fiood insurance raquvemenis etthe NPR as WeY apptytoapvtieular pmpany. ALOMAisaotsboi}dmg pwmil,mx shaWd hbe eornnotda~uch Aay development, nee cooaou,Kitn, oravbahmial impmuemmtofa property impactedbya L.t1MA moat comply wiW aR appiicabie State end local criteria end othm Federel critwia. Ifs Imdxreiases aproperty owner Gom the flood msuraoceraluiremeot,and We property ownerdecidn ro caxal We polity and acek a refuvd, dre NEIP will ttfuad dre premium paid fw du current polity year, provided Polatwckimis peadiag orhasMapaid oo rhepolicydaring the eaman policy year. Theproperly owner rtstutprovide a writta waiver ot[he iostemce rvgvirommt Gam tiro lender ro the property instmmce agml a comWnY emvk:ing bin w Iwr policy. The agem w Company will Wee process the tttuml raptnt SamtlenrrghaM+csma tnenmlaated tnaa SFHA, asrneoconadabovq they coddbo floodedby a Hooding evanf wiW a grerrra magWtude then We base flood. In feat, more dun 25 perteW of all claims paid by ibe NPtP arc for polieiee for atrrrttwo located auaide the SFHA N Zmwa 13, C, X (ahW W). w X (wahaded). Mwa Wm ~e-fourW ofeil policies purofuaed wtdartbe NF'@ protect strauurrv loafed iadsae zmrs. The ruk manvcmcer located waide SFHAB ujust trotaagreat a the riskro stmeMes bcatedm SFtW. Finally, apprezimaely 90 percent of W federally deWared disasters are eased by flooding, and homeowners Iomnaace doanotprovWC Fmmciaiprosection from tide floadmg. Therefore, F&MA rncoungea We widest poss3lewvaage rawer fl[e NFIP. LOMAENC-I SAMANTHA RIDGE 126501 PAGE 22 APPENDIX B -Hydraulic Analysis SAMANTHA RIDGE ~ 7-05 07 PR6E 23 PROPOSED DETENTION POND SUMMARY: PI~O~POlD61MMIM O~QIMalAQO'a100m' o~nt s K o~ raro i r mff ewRO) eona+ of ro~o aFVAnore mm ioroPVarQaaao nao vauE ~Raro~ ~,aooao a. Fr pans otie+e®J raovaurl~aauscuFr. .,- ./,__ ;~ //„_ ~ ~/ ~ .~\ ~ I ~ r tt fll III I I \ 1~~ \ I I \ ~~ \ I I I ~\\ ~~~ II I I ~\\\~~ II I 4'HIGH CHAIN LINKFENCE V A A ~ ~ ~ IIII -(SLACK OR GREEN VINYL COATED) 1\111 I IIII I 1 I I I 5'PEDESTRUW PATH 11 I Illlll I I l11111 11 III 1 1 ~AVV~ A 111 ~~~~ ~ 1 1111 1 •w~~ 1 II I I ~ ~~~~ I 111 ~ ~ ~ 111 ~ ~~ ~ j il~}~~ ~~~~~ ~ ~~~ ~ 1 ~ ~~ ~ 111 11 ~ VA I .B. 111111 11111 ~B. III I 1111 11~~~ i ~_~o a ~ 1~11 l ~ ,~ o%o.,a i ma°o°~ / / ~~77 WIDE ACCESS GATE 12 WIDE POND FOIm FOOT FflNi NL~ SAMANTHA RIDGE 1 <^ 05 07 PAGE 2a SAMANTHA RIDGE 12 05.0'! PAGE 25 ~: W~.E,EE.E~..®E ..,~.oE.~E.,a ~..~W~W EE,~E~,W,.w..~ E,.~„~E~W.~ ~WEm~~~ w~.~a~W~R ~E~W~W .~..~. to _ ~ / FI L~~ PLAN v~Ew e - e SECTION A - A .°~nu..em,:mwr ~pngE..EE r.e.n.w~~'oxiewmweirvn..®mrruvneY»xba. EEroeaa~aE~+~ECn~ ~ ~` manmwaeiaw EmliErrrwEEeEewxEnEeromrrn m a IMTCYIIILNIW W1l.MEEEp®EIU/lEf6W S MOYWLECNIMW MEL6lMO~MfA.4lIK /IIVBMO9~V~1®9.HPiM®I~IM~1fR1410IM4Y® ~YLLEEOl.~EEEpE11W1EliE EE ¢IWIIIA{1E91ElCWdIGY.YiIN1R0.VlMVNWWUIicnlo EW MIINI.COfIM®BERVATO ~ N IXYIAI WIIdB EETCI~ERGMOII' ffG1~00lY01®IEWIM9IEIEOE~/.O.aE9WB. llIITMOiNNEMMIIICYL~AMEElMYI YMNtlW1Ep11WN11111YY101W W94 L MI~IWIClEMY.YE®fIWERMIX~WIE/YtNWfY PROPRIETARY INFORMATION - NOT TO BE USED FOR CONSTRUCTION PURPOSES ~m°~Opnmiwuu: ~``.".s:°i.wnmi"w"1.'+.~M1PO1.....m~r..w°1VY.s.°re°°r i~.a«w+~..e°.~s~ ne+aramwaua..a...amnm~E~.rru.w.m.~.~..wre~rrv W r E..~. ~ STANDARD DETAIL STORMWATERTREATMENi SYSTEM ~Vf10 5_ VORTECHS"MODEL 2000 ETi SAMANTHA RIDGE 12. QSD~ PAGF_ 26 PRE-DEVELOPMENT STORM EVENT SUMMARY __ _._ Event _, Peak O (cfs) Peak T (tire) Hyd Vol (acR)I Area (ac) Method Raintype.. 6-month j _ 0 3386 7 83 ', 0 1078 1 3000 SBUH TYPEtA'.. 2 year , _ _0 5991 ' 7 83 0 1922 _ 1 3000 SBUH ~ PE1A 10 years __ 0 9235 ~ _, 7 83 0 2999 1 3000 SBUH ~TYPEIA 25 year _ 10844 __ 7.83 0.3539 !. 1.3000 SBUH TYPEIA•. 100 year,._ 12448 _ 783 _ 04079 13000 ,SBUH TYPEtA PRE-DEVELOPMENT AREA SUMMARY Design Method ~~ SBUH Rainfall type r TYPE1A Hyd Intv , _ ' 10 00 min Peaking Factor ~-Abstraction COeH 484 00 .020 Pervious Area (AMC 2) ',r 0 00 ac CIA ~~ 1.30 ac -__ Pervious CN -_- _ 0 00 DC CN__ I 98 0000 _ _.__ ___ ~__ Pervious 7C _ r---~ 0.00 min DC TC ~ 0.56 min Directly Connected CN Calc Description ~SUbArea j Sub cn ' Impervious surfaces (pavements, roofs, etc) j 1.30 ac ~ 98.00 ~, d CN(AMC 2) DC Composlt ~_ { 98 00 J - ~ Drrectl Connected 7C Calc ~ Type ~ Descnptron ~ Length I IS ope Sheet ~~ Smooth Surfaces 0 011 f30 00 ft I~10 00% 0 ft 2:00 / rChannel (intern) Concrete Plp t 0 ~ Coeff Misc ~TT 0 0710 IO 00 In ~i0 00 mm ' 0 0120 ~ I ~_.- Connected TC Dire ly 0 S6m n ! SAMANTHA RIDGE 'r <.OS Oi PAGE P POST-DEVELOPMENT STORM EVENT SUMMARY Event ~ Peak D (cfs)~ Peak T (hrs) Hyd Vol (acff); Area (ac) Method, Raintype.. 6 month; __ 03386 7.83 _ 01078 '. . 1 3000 SBUH TYPEIA 2 year i _ 05991 783 01922 ' x13000 SBUH TYPEIA 10 year 0 9235 7.83 0 2999 1 3000 ~ S UB H rTYPE1A'.i r 25 year 1.0844 i 783 100 year 12448 ~ 7 83 03539 0 4079 _ 1.3000 IS H TYPEIA~ r 1 3000 SBUH P A' POST-DEVELOPMENT AREA SUMMARY Design Method ~ SBUH (Rainfall type TYPE1A i, Hyd InN ~ 10.00 min Peaking Factor ~ 84.00 Pervious Area (AMC 2) j 0.00 ac DCIA ~ 1.30 ac Pervious CN _ ~ 0.00 ~DC CN ~ 98.00 __ Pervious 7C 0.00 min jDC 7C ~ 0.56 min tl Connected CN Calc y ~ i (r r SubArea ~ Descript on I~ Sub cn , Impervious surfaces (pavements, roofs etc) I 1.30 ac '~;r 98 00 ;i ~ DC Composited CN (AMC 2) ~ 98 00 ~' r Directly Connected TC Calc I ope ~ Coeff ~ Misc i th TT - n -~ 0.00°/ `0 0110 ~0 00 in X30 00O ft ( nt r0 00 min ~ ~~~- ~- ~hannel (i term) 2 200.00 tt 0 012) ' 00°/ 00120 Concretee p pe ( I 056 min Directly Connected TC ~ 086mi~, SAMANTHA FIC)GE 12 OS G7 PAGE 28 HYDROGRAPH PLOTS PRE &POST-DEVELOPMENT 2 YEAR HYDROGRAPH 0.0990 Time to 2 year Hydrograph Plot 0.6 - -- - - _~ -- ------ ~__~- - __ - - - ~_ -~ - I I I . . X0.3 __~-- -~ T --'~-- o 0.1 0 °o m m ~ p+ .n- °o m m v°~ m ~ g~ ~n ~°n m~ °o, ~i n ~ o m m ~°n, rv rv cr < ~n ~ti n n a m o ~ rv N M° N ru n n m °' r°,~ iv rv rv rv rv Time n Haurs' PRE &POST-DEVELOPMENT 10 YEAR HYDROGRAPH Start of live storage: 330.00 ft 0.0798 to Empty 0.H ~0.6 ~ _ C ~~0 LL ~.2 D 0 10 N O r fV N t+( ~ O 2, N 1~I1 m ~ O m~ N Cl ~ O ~ IO ry~ tM+j r n 4'1 N O O E M 1'1 ' s H b ~ m m fV f~V l~`I N N !aV f Time m Hars ------ PAGE 29 SAMANTHA RIDGE ~~DS~ PRE 8POST-DEVELOPMENT 100 YEAR HYDROGRAPH Start of live storaoet 330.00 ft 700 year Hydragraph Plat , , I i ~ _ ,__ ~ _ __ _ __ __ . __; y j*p __~__r __~__~_~_ _ ~__ __ __ __ ~1 c LL e m ,~ N~ ~ m 0 ID N M I O m IrU VI Im'I ~ S m b N.m m'~ ~ m ~ 0 m ~ rv of a v ~n m n ai m m o .- ~ M a< r m ~ m m m~ rv rv cMi rv Time in Haurs DETENTION POND SUMMARY -- I p YP I _ -r ___..._I Descrl ~ Protot a Record Increment 0.10 ft Starl EI. _ _ 330.0000 ft Max EI r335 0000 ft~ IStorage Node Pond _ Discharge Node'Sp Trench; = REQUIRED VOLUME SAMANTHA RIDGE 12.05 0] PAGE 30 ~ vFeR nl1T _ HvoROGRAPH SUMMARY Area Hyd Int ~ 10.00 mm Base. Flow 1 3000 ac Peak flow.. . 0 0990 cfs Peak Time 12.17 hrs Hyd Vol 0 1922.acft Time (hr) I Flow (cfs) Time (hr) Flow (cfs) I Tim7im hr~ Flow (cfs) ' ~ ; 0.0000 :14'110 ~ 0.0985 28.6 0 0711 ti c ~;% 0 0010 f ~ t .~ 0.0984 ~ .$2 ~ 0.0701 00027.. _~ 0.0983 ` 2'4 0.0690 I .~} _ : `,: r0 0048 ~ ',' 14;50 ~ '0.0982 Ir1'~' r 0.0680 _- I~.%k, ''~ .0073 ;; ,1 0.0981 ,27;39 ~ 0.0669 00101 ,p'~; ~.0.0980 ~ "7.~iD ~ 0.0658 2 1j x0.0132 i _.1 0 _~ __0.0979 ~ 27.87 ~ 0.0648 SAMANTHA RIDGE 120 0] 'AGE 31 PAGE 32 SAMANTHA RIDGE 12.06 0/ Area _! 1 3000 ac, .Hyd Int .10.00 min Base Flow.-. Peak Bow'. 0 4179 cfs. Peak Time 8.33 hrs Hyd Vol0.2999 acft Ti e I Flow (cfs)' Time (hr) Flow (cfs) Time (hr) Flow (cfs) ~ 8y~9 ` ~..~00000 ;. 146,.-x0.1314 26:93 j. 0.0776.__-I o oola ~ ~~2as ~~f o.o~ss_ i 00040.1269 `2,8: T li 0„0756 ~ ,,~-..i 00 077 ^ ~f~t7, .,.I y.1261 28:93 ~0.0747..,~ 1;$iJ , 0 0121 _ ~_' S1 ~ .~ 0.1256 r 29.00 _ 0.0737__ I ------ -'- FAGE 33 SAMANTHA MIDGE /2 GS G] 10 YEAR OUT - HYDROGRAPH SUMMARY nAGE 34 SAMANTHA RIDGE 12 05 0' -___-- -_ -- --_ ----- ---- '-- PAGE 35 SAMANTHA RIDGE 12 OS 0] ._ __ ...__ _. _ PAGE 36 SAMANTHA RIDGE 12 05.4] PAGE ?] SAMANTHA RIDGE - 1200/ SAMANTHA RIDGE 12.05 0] PAGE 38 __ _. __..___-0 4696 cfs.. 1.3493 cfsl, ~~~ 1.3267 cfs SPREADER TRENCH SUMMARY Descnp Prototype Structured Incremenh.0 10 ft ~ Start EI. 328.0000 ft __ ~ Max EI. i 330 0000 fP; SAMP.NTHA RIDGE 12 05ID PAGE 39 APPENDIX C - Geotechnical Report 12.05.0] PAG[ 40 b6-G3~ ' Gary A. Flowers, PLLC Geological & Geotechuical Cousultiug 19532 121° Avenue NE Shoreline, WA 98155-1106 August 4, 2006 Project No. 06-079 Pacific Frontier, LLC 111 5th Street NE Auburn, WA 98002 Attention: Mr. Jack Long Subject: GeologicaUGeotechnical Assessment Crystal Springs Property Crystal Springs Road NW & Edwazds Road NW Yelm, Washington This report presents the results of our geologicaVgeotechnical evaluation of the approximate 4.1 acre property located at the east side of the intersection of Crystal Springs Road NW and Edwards Road NW in Yelm, Washington. It is om understanding that the property will be developed to support single family residence lots. Site layout or grading plans were not available at the time of this report. The purpose of our site evaluation was to document existing shallow soil and ground water condifions on the property, and to provide geotechnical design recommendations for construction of the proposed improvements. EXISTING CONDITIONS The subject site is an hregulaz triangular shaped parcel measuring approximately 4.1 acres. The west side of the site slopes down from the adjacent mad elevation to a lower flat area occupying the majority of the property with a slight slope to the northeast. Total elevation change across the property was on the order of 20 feet. A single story residence and attached garage are located on the southwest comer of the site. Prialary vegetafion is field grass with a few shmbs and bushes. Several flair trees and deciduous trees were located along the western side of the properly. A small stream bounds the properly on the east side. A utility easement with fiber optic lines bisects the property in the east-west direction. There was a collapsed old well house, presumably with an open well under it, to the north of the utility easement at the base of the west slope. m Gary b Flowers, PLLC 19532 t2 Avenue lJE ShorGux, Wsshwgton 98155-1106 20641 ~-'1560 Crystal Springs Property GeologicaUGeotechnical Services Report Ye(m, Washington Subsurface Soil and Ground Water Conditions In order to characterize the shallow subsurface soil and ground wafer conditions on the properties, a series of 8 subsurface exploration pits were completed using small back-mounted excavator provided by the client. The explomtion pits permitted direct, visual observation of the subsurface soils on the property. The exploration pits were logged by a licensed geologst and immediately backfilled. The exploration pit locations are shown on the site and explomtion plan attached to this report. The exploration pits revealed that the site was. underlain by Spanaway recessional outwash sand and gravel. Minor fill soil was encountered in the southwest comer of the properly. The topsoil layer was very non-uniform across the property. Little to no topsoil was encountered in the exploration pits except for EP-4 and EP-7 where it was found to be 4 and 2 feet thick, respectively. The topsoil layer supporting the field grass at the remaining explorations was about 2 to 6 inches thick before grading into the recessional sand and gmvel. The topsoil was loose, dry, dark brown, fine sandy silt loam. The upper 4 W 5 feet of EP-B-consisted of loose, dry, brown, gravelly sand with some silt and conshvction rubble. This material was SII soIl of unknown origin or age. Under the fill or topsoil layers in all of the exploration pits were Spanaway recessional sand and gavel deposits. The recessional outwash was deposited from fluvial processes during the retreat of the Vachon stade of the Fraser glacial period about 10,000 years ago. hffiltmtion into this unit is typically moderate to rapid. The outwash sediments consisted of loose to medium dense with depth, dry to damp, brown or gray-brown, sandy gravel and gravelly sand with minor silt. Often the sediment layers contained a significant cobble and boulder content indicating a high energy depositional environment The outwash deposits extended below the temilnation depths of all of our explorafions at 5 to 10 feet. 1n EP-3 and EP-], the sediment was saturated below 8 and 9 feet respectively. Hydrology There was a small stream along the east side Of the property that was highly overgrown by shmb and blackberry vegetation. There was no evidence of erosion anywhere on the parcel that we could observe but due to the dense vegetation along the stream corridor, the stream banks were not visible. Ground water was encountered in EP-3 aqd EP-7 at roughly the same elevation, about 8 to 9 feet below ground surface. The ground water likely represents the local water table for this area. The ground water elevation will vary with the time of year. Gary A. Flowers, PLLC. 1953212'"AVCnue NE ShorcAinq Wazhington 96155-1106 20641]-]lA0 Crystal Springs Property GeologicaUGeofechrsica! Services Report Yefm, Washington Seismic Hazards Generally, there are four types of potenGalgeologic hazards associated with large seismic events: 1) surficial Bound mplure; 2) seismically induced landslides;-3) liquefaction; and 4) Bound motion. The potential for each of these to impact the site is discussed below. A few known fault canes occur in the Puget Sound region, however none are currently known in the Yehn area. Fault zones in the Puget Sound Legion aze currently being studied by the United States Geological Service (USGS) and have been deternvned to be active and capable of producing lazge earthquakes. Much is still to be leazned about these fault systems but it is generally hypothesized that their- recurrence interval is several thousand years. Due to the suspected long recurrence interval and the lack of known surficial faults traces, the potential for surficial Bound rupture is considered to be low during the expected life of the proposed structures. Due to the free draining nature of the sediments comprising the slope and its relatively low topogaphic relief, it is our opinion that the potential risk of damage to the proposed structure, by large scale seismically induced landsliding, is low. Based on the densiTy and gain size distribution of the sediments encountered in our exploration pits, it is our opinion that the risk of liquefaction on this site is low. Based on the encountered stratigraphy, structural design of the project should be consistent with 2003 International Budding Code (IBC) guidelines. In accordance with Table 1615.1.1 of the 2003 IBC, the subject site would be classified as Site Class D. CONCLUSIONS AND RECOMMENDATIONS On the basis of our geologic research and field explorations, the property will be suitable for the planned development. The upper surficial silty fine sandy loam topsoil where encountered on the site may be problemafic for structural development and should be removed from foundation areas. Similarly, the old fill soil where encountered should be removed and replaced with documented structural fill from all foundation or roadway areas. The near surface medium dense recessional sand and gravel outwash or dense lodgment till sediment will be capable of providing suitable foundation support for the planned roadways, parking areas and structures. The old water well on the site will need m be abandoned according to Washington State Dept. of Ecology (DOE) standards. A well abandonment record will need to be Sled with DOE and as such, a licensed well driller should be contracted to perform this work. Gary A. Flowers, PI,I.C. I953212mAVmue NE Shorelwe, Wazhingfon 98155-II06 2p6-g13.~6dp CrysfaJ Springs Property GeologicaUGewechnical Services Report Yelm, Washington Silo Grading The existing vegetation on the site shall be removed from all areas planned to be graded as part of the planned development. The organic topsoil is relatively thin in most areas and should be should be removed from all structural areas even where it is 2 to 4 feet thick. A grading plan was not available at the time this study was completed. As such, we are unsure as to final grading plans for the site. However, it is anticipated that some stmctuml fill will be required to develop dre planned property. Structural fill is nonorganic soil that is neaz optimum moisture content. The fill soil must be placed in maximum 8-inch loose lifts with each lift being compacted to a dense, non-yielding condition prior to installation of the succeeding lift. The moisture content must be near enough to optimummoisture content to allow the fill to achieve the required compaction. Compaction effort must be applied to achieve a minimum of 95 percent of the modified Proctor maximum dry density per ASTM:D-1557. Tn addition to being monitored by a representative of this fum, the placement and compaction of stmctural fil] should be tested using a nucleaz densometer to verify that suitable compaction is being obtained. In the case of utility trench backffil, the structural fill should be placed and compacted in accordance with current local or county codes and standards. The top of all compacted fill should extend horizontally outward a minimum distance of 3 feet beyond the location of perimeter footings or pavement edges before sloping down at a maximum angle of 2H:1 V. It should be the responsibility of the contractor to maintain safe slope configurations since the contractor is continuously on-site. As is typical with earthwork operations, some sloughing and raveling may occur and cut slopes may have to be adjusted in the field. It may be necessary to cover [he sides of temporary slopes with plastic or otherwise protect them firm the elements to minimize sloughing and erosion. For estimating purposes, we anticipate that temporary, unsupported cu[ slopes can be made ai an inclination of 1.SH:IV (I-Iorizonml:Vertical). Permanent, unsupported cut or structural Sll slopes should not exceed a gradient of 2H:1 V. Permanent, non-stmctural fill s]opes should not exceed a gradient of 4H:1 V. Foundation Recommendations The planned residences may be set to beaz on documented stmctural fill soIl placed as discussed above or on undisturbed medium dense gravely sand on-site soils. An allowable soil bearing value of 2000 psf may be used in the design of the house footings, including both dead and live loads. An increase of one-tktird may be used for short-term wind or seismic loading: perimeter footings for the proposed structures should be buried a minimum of 18 inches into the surrounding soil for frost protection. Settlement of footings placed as detailed herein should be less than- 1 inch between comparably loaded foundations. However, foundations placed on disturbed soil may result in increased settlement. Steps in the foundation grade are acceptable Gary A. Flowers, PLLC. 19532121°AVmee NE Shoreline, Washing1an 98155-1106 206A1]-]640 Crystal Sprtngs Property Gea(ogicaUGeatechnica! Services Report Ye(m, Washington provided that none of the foundations are set to beaz adjacent to the step. A 1H:1 V load line extending down from the edge of the foundation must not daylight on a cut slope. All foundation excavafions should be inspected by a representative of this firm, prior to concrete placement, to verify that the design bearing capacityof the soils has been attained and that conshuclioh conforms to the recommendationscontained inthisreport Lateral loads can be resisted by friction between the foundation and the supporting soils, and/or by passive earth pressure acting on the buried portions of the foundations. The foundations must be backfilled with structural fill compacted to a dense, nonyielding condition to achieve the passive resistance provided below. 1'he structural 5ll must extend horizontally outward from the embedded portion of the foundation a distance equal to at least throe times the embedment depth over which the passive resistance is applied. We recommend the following design parameters. • Passive equivalent fluid = 250 pct • Coefficient of friction = 0.40 The above values are allowable and include a factor of safety of at least 1.5. Floor Support Recommendations Slab-on-grade floors should be set to bear on undisturbed native soils or stnrctural fill in a firer, unyielding condition. A caplIlary break layer consisting of 4 inches of washed pea gravel and a heavyduty (minimum 10 mil), polyethylene plastic vapor barrier should be provided under any floor slabs where moisture intrusion is a concern The on-site clean sand and gravel, if free of silt, may also be used as a capillary break layer. If the vapor bamer becomes compromised in any way during construction it should be replaced or an additional layer added. Penetrations through the vapor barrier should be wrapped and taped. Site Drainage All storm water runoff from impervious surfaces should be collected and piped into an approved stone water drainage system. Individual lot i~ltration trenches or dry wells would be an option for this site. Footing drains are likely not needed for this site provided the foundations aze placed atop the clean sand and gravels encountered in our explorations. ff footing drains are utilized they should consist of rigid, perforated, PVC pipe surrounded by washed pea gravel. The level of the perforations in the pipe should be se[ approximately at the bottom of the footing and the drains should be wnstmcted with sufficient gradient to allow gravity dischazge away flora the buildings. Footing drains that will have more than 8 feet of backfill should be constructed of schedule 3034 or better sewer grade pipe to minimise potential for collapse. Roof and surface runoff should not discharge into the footing drain system, but should be handled by a separate, rigid, tighdine drain that discharges into an approved storm water conveyance system. Tn planning, exterior grades adjacent to walls should be sloped downward away flora the structuue to achieve surface drainage. Gary A. Flowers, PLI.C. 1953212'"AVenue NF, ShoNina, Washuigm¢98155-1106 2o6dV-]640 C7ystal Springs Properry Geological/Geotechnical Services Report Yelm, Washington Due to the high ground water table encountered in several of the explorations, a lazge scale ihfiltration pond may not be suitable for this site. Additional in-situ testing and ground water modeling analysis should be performed to evaluate for ground water mounding if an infiltration pond is to be utilized. However, individual iot infiltration systems aze suitable for the residential properties. For roadway runoff shallow infiltration ditches along the roadway may bean option provided suitable pre-treatment can be accomplished. Any infiltration facilities should penetrate through the loamy fine sand to the underlying recessional outwash sediments. The materials encountered in our exploration pits would be classified as sand per the USDA Textural Triangle. Per the Dep[. of Ecology's Western Washington Storm Water Manual, these materials have an allowable short term infiltration rate of 8.0 inches per hour and an estimated long term infiltration rate of 2.0 inches per hour with a correction factor of 4. Due to some variability of the sediments on this site, and the relatively high water table, ii is. our opinion that the higher correction factor is appropriate and a maximum design rate of 2.0 inches per hour should be used for this site. The design eagineer should take this information into account during the design process. The infiltration facilities should be developed in accordance with requirements of the Lxal jurisdiction for storm water n3noff. SUMMARY Based on our site reconnaissance and subsurface explorations the site appeazs to be suitable for the proposed development provided the recommendations presented herein are properly implemented. We recommend that we be retained to review those portions of the plans and specifications that pertain to grading or foundation installations to determine that they aze consistent with the recommendations of this report. Conshuction monitoring and consultation services should also be provided to verify that subsurface conditions are as expected. Shouid conditions be revealed during construction that differs from the anticipated subsurface profile, we will evaluate ffiose conditions and provide alternative recommendations where appropriate. Field construction monitoring and observation services should be considered m extension of this initial geotcehnical evaluation, and ate essential to the determination of compliance with the project drawings and specifications. Such activities would include site clearing and grading, subsurface drainage, foundations bearing and fill placement and compaction. Gary A Flowers, PLLC. 1953212°Avenue NE Shomlme, Washington 98!55-1106 206~4llA640 <}y5tal.Springs Property Ccnfugicaf/Gentechnirnf .tierci(•et Ripon }'efm. ib'achinfiton Our findings and recommendations provided in this relxrrt were prepared in accordance with genemJly accepted principles of engineering geology and gcotechnical engineering as practiced in the Puget Somd area at the lime this report was submitted. We make tro other warranty, either express or implied. Sincerely, eo Wasyl y° Q ~ ~ °~ f~cpnteQ Gco\oq Gary A. FlOwera c)a,y A. Plnwera, r.G., P.E.c. Engineering Geologist Jamey S. Battermann, P.E., L.G. Geotectutical Engineer Attachments: Site Pkan Appendix A -Exploration pit Logs Cary A. Nluwen, PLLC 19S]212°rhvcnuc NL SMvcanc, WmM1inpnn Ya155-I Ie6 3114-01)-](NO EXPIRES [t-2B - --- - - _ ~_ . i I ~ ' ~ _ _ - U -~ . ~ C _ C ~ v ~ ~ ' '~ ~ 0 ~ ' p '". .' CCj c .L L a o i N M 0 W , U ~ Q ~ Q = ~ I li ~ ~ a ~ i~ ~x~ a 3 ;z y ~ C ~ a ~ % - ~ - ~" ~ a ~ U . 'L ~ + o ~ ~~ ~ c~C n _ N I ',., a ~ ~~ 4 II 1 /'~ ~1 .U ~ III X ~ ~ / / wl III r-+ O ~I ~ ~ O ~. f ~ ! ~ 0 p ~ ~1. ~ _~=~~~ a 1 ~ iii , ~ ~ Q ,~ ~ , / I i I ~; ~ M ~ ~ ~~ ~: W ~ ~ ~ ~ _ ~ ~) ~ ~ ~~ ~~ _ ~ ~ ~~ ¢ g m ~. y y -.. ~J LJ ~ ~ _ J 0 ~ W - ~ I t __ ~ ~ p_ U ~ L I s L ~ w L ~ -~. . ~~ __ ~ ~ j~ ~~ ~ ~ , G O iii o ~' ~ ~..._._ MM.. -~ i . L I - ~ ,` Z N ~ ~. __. `' ~ Q ~ ~ ¢ ~~ Cti-(i ~''~ z... ea ~ o N a 01- c ~ onN o ~ ~n ~' ~PH Crystal Springs Geo7ogicadGeotecMica7Servkes Report Crystal Springs Rd. NW & Edwards RoadNW APPENDIX A EXPLORATION LOGS Gary A. Flowers, PLLC. 19532121°Avmue NE Shorcliny WUhing[ov 98155-1106 206-01]-]640 EXPLORATION PIT LOG 1 2 3 4 5 6 7 8 9 10 11 12 13 o Number EP-1 SPANAWAY RECESSIONAL OUTWASH Loose to medium dense, dry to damp, brown, sandy gravel with cobbles. BOH@6' Minor Caving No Ground Water Seepage •~^~ ~ rsuapnw,eprew,nw,raoservmon acme emoam alcaaon olmu eaparaury npa, morXetl by 9edogk Nlapretatian, en9in¢eri~g anaYSs. anO ryUgmenL Th9y ara relnewssetSy repreBenralrve MdherMmes an6bfafgn. Y&'sillnw assaPl recport bifity for Ne use avdrpreWUrtWaPers of imlormanrcr Plssanlcd an tlus b6. Crystal Springs Property GARYA. FLOWERS, PLLG Yelm, Washington July 10, 2006 EXPLORATION PIT LOG 0 1 2 3 4 5 6 7 a s 10 tt 12 13 Number EP-2 SPANAWAY RECESSIONAL OUTWASH Loose to medium dense, dry to damp, brown, sandy gravel with cotibles. BOH @ 6' Minor Gaving No Ground Water Seepage aaxmam commmsaap[ma repla¢alll our oa¢ercauon at tM dme aM Im2Wna(ttk avpbnrory hqe, matlif V hi' pedop¢ InRrpelallon. eMir~cla9 analym, eM ~ua9menL They are nolnmeasayNY Kpesenlahw MomMllmes silo laeelgn. Nh wnl trof B~pl lespw 9ihlty lrc the uee of N6Yp[elelm hydliers of in(ixmetiOn aRiblletl vn aia kg. Crystal Springs Property GARYA. FLOWERS, PLLC Yelm, Washington July 10, 2006 EXPLORATION PIT LOG 1 2 3 4 5 6 7 8 9 10 11 12 13 NISOUALLY LOAMY FINE SAND Loose, dry, dark brown, fine sandy loam. g Number EP-3 SPANAWAY RECESSIONAL OUTWASH Loose to medium dense, dry to damp, brown, sandy gravel and gravelly sand with cobbles and occaisionalboulders. Becomes saturated below 8' BOH @ 10' Minor Caving Moderate to Rapid Ground Water Seepage @ 8' supsuttece ceeumons OeprAep Ryesenf ouropsgvaliry, $ Ve ymu aM Iputlma(Inhepaoretary pqe, nNIpPA by WuloUlc inleryretalloR e,gilleenlg alialyaic,aM juJgaumt TM1ey aenW rea+aratdy lepeeel0alrve dotl,erlimea Bed lrcdWn. N4wII1 nOl eCIXpi lesppn&UUry IMNe use D! ~n1elIYe1MM Oy pUtYS pllniP'm3UIX1 Dlepenk0 M Ula bp. Crystal Springs Property GARYA. FLOWERS, PLLC Yelm, Washington July 10, 2006 EXPLORATION PIT LOG 0 1 2 3 4 5 6 7 6 9 10 11 12 13 Plumber EP-4 NISOUALLY LOAMY FINE SANQ Loose, dry, dark brown, fine sandy loam with trace gravel. SPANAWAY RECESSIONAL OUTWASH Medium dense, damp, light brown, fine to medium sand with some silt and trace gravel BOH @ 6' Minor Caving No Ground Water Seepage .._ __'.___._~_..._........,~..o„~,.,.F ~~~~~~.~~. wcwan m miseag,orerory nwe, mawiea oY 9e~A< Inraryre~yyp~. epQlpRt,MJ anayeic. an,INtl8ma4, TtleY ere nolneceeemly reryesengYUe of over tlmesaM lrca(gn, We wle nM accept R9pMStdtlly Ib pn use a inroryrekbun by otl,xs o4iNgmstlpn pesenmtl on Ua IOp. Crystal Springs Property GARYA. FLOWERS, PLLC Yelm, Washington July 10, 20t)6 EXPLORATION PiT LOG 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Number EP-5 SPANAWAY RECESSIONAL OUTWASH Loose to medium dense, dry to damp, brown, sandy gravel with cobbles. BOH @ 5' Minor Caving No Ground Water Seepage CUDaUrface CP'b~114 QefACLLq repea211toW otpC'rveben M Ne Nm. a4,Q bbtglof IM80%~2IMY f.1e, 11fOlf.'(atl ~ pEOlagic iMap,elatim. En9i„eercg analYae.eM IW9mML 1MVere MIneWSSeNYRMe9erltaYVe afOlllCf tMes aM lhA4on. NU wll nat aamptraspons2bl:ty rar the ose or bRrpretafion by Mf,ers W inwmation pc• nteb on C,q log. Grystal Springs Property GARYA. FLOWERS, PLLC Yelm, Washington July 10, 2D06 EXPLORATION PIT LOG 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Number EP-6 SPANAWAY RECESSIONAL OUTWASH Loose to medium dense, dry to damp, brown, sandy gravel with cobbles. BOH @ 5' Minor Caving No Ground Water Seepage ~ seperes repacemmomarvamn 9l me ame antl lU2liMaf Nlseapbratary title, moaifx:U lry gedogic nt¢raretdtipl, engltleerirg atulyss, aM jWpnprd. Thy ere rot necessarily represerratira datM1er limn eM Pocstbn Yp wN rrat ePRpl respJnslMlTy la IM1e uEA or Inleryeetalirn by pll,e,5 o/inlemBtlM pIp53M1IeE Ort tlYS Imo. Crystal Springs Property GARYA. FLOWERS, PLLC Yelm, Washington July 10, 2006 EXPLORATION PIT LOG t 2 3 4 5 6 7 8 9 10 11 12 a Number EP-7 _.__ NISQUALLY LOAMY FINE SAND Loose, dry, dark brown, Flne sandy loam with trace gravel. SPANAWAY RECESSIONAL OUNlASH Medium dense, damp, light brown, fine to medium sand, with some silt and trace gravel Medium dense, damp to wet with depth, brown, gravelly sand with cobbles and boulders. Becomes saturated below 9' 13 r sureprtvice wndGOns EspkleE represent our abservapm at M time anEbcaticn OI OIa m¢loroldy ack. motllaeJ M 9epbg< rae~pelation. ergmearinp a,atysis. an0ryajrimnt TnY tte not r~ecessanry ~ep~asenletWe Nodrer limesaM lc®tion. 4Ve vAlnN r~pf raaponslMltty for bie vso or4ltBrprEfatipn bYparem W inswmaAan presemea m mrs ag. BOfi Q 10' Minor Caving Moderate to Rapid Ground Water Seepage @ 9' Crystal Springs Property GARYA. FLOWERS, PLLC Yelm, Washington July 10, 2006 EXPLORATION PIT LOG 0 1 2 3 4 5 6 7 8 9 10 11 12 Number EP-8 FILL SOIL Loose, dry, brown, sand with some gravel, silt and construction rubble. SPANAWAY RECESSIONAL OUTWASH Medium dense, damp, light brown, fine to medium sand-~ with some silt and trace gravel. 13 Subeucfageman014ona 4epkR],epresent our oGServalbn al Te Enx arq laa6an of lM1iS evplwabry Mk. moEl(ceC 0y 9aaKKllc intemrelatpm enp,wen~g analyaia, am Juapment. TInY arergl na2asaHlY repfesenteU~e d oCw6mex am bmuon. Np wit nat accwtrespons~bNiry for the use wMrerpmmfion W atM1e+s ofmtartratim, p,esent d cn ues,og. Crystal Springs Property GARYA. FLOWERS, PLLC Yelm, Washington July 10, 2006 BOH@T Minor Caving No Ground Water Seepage