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05-0770 Drainage Erosion Report 022008
RECEIVED fEB 22 1008 SAMANTHA RIDGE Drainage and Erosion Control Report Prepared for: Jack Long The One Eleven Building Auburn, WA 98002 (253) 846-5756 February 20, 2008 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: 66-036 Project Name: SAMANTHA RIDGE Storm Report -Samantha Ridge.doc ... ~rr ~NGZ:~EERI~G, LLC 638 DOCl(6TREET•SUITE 213 ITACOMA I WAI 834821 PHONE 1283)i52-TBiT I FA%(263)Tfitd682 I YANYY.PETRAENG.NET TABLE OF CONTENTS I. FACILIN SUMMARY FORM ............................................................................... ...................3 II. PROJECT ENGINEER'S CERTIFICATE ............................................................. ...................7 III. DRAINAGE REPORT ............................................................................................ ...................8 Section 1 -Project Description ......................................................................... ..................8 Section 2 -Existing Conditions ......................................................................... ..................8 Section 3 -Infiltration 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 Section 12 -Other Permits or Conditions Placed on the Project ..................... ................10 Section 13 -Bond Quantities and Declaration of Covenant......_ ..................... .. _..._.......10 IV. EROSION CONTROL PLAN ................... .................10 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 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 - Proiect Name and Proponent Project name: Project owner: Project contact: Address: Phone: Project proponent (if different): Address: Phone: Project engineer: Firm: Phone number: Samantha Jack Lonq Detention Pond Crystal Springs Road NW #15854-001-Ot 22719240600 PETRA Engineering 535 Dock Street -Ste. 213 Tacoma, WA 98402 12531752-7617 Pete Swan PETRA Engineering (253) 752-7617 Part 2 -.Project Location Section ............................ Township ........................ Range ............................. 19 17 n~ Names and addresses of adjacent propertv owners: Floyd Cummings (North) 614 Crystal Springs Rd. Yelm, WA 98597 Pacific Frontier, LLC (East) 406 Crystal Springs Rd. Yelm, WA 96597 Clarke Properties, LLC (South) 404 Railroad Ave SE Yelm, WA 96597 Ryan & Tami Pearson (South) 404 Edwards St. SW Yelm, WA 96597 Troy Truong (South) 402 Edwards St. SW Yelm, WA 96597 Michael Killion (West) 15744 Coates Rd. Yelm, WA 96597 Part 3-TVpe of Permit Application Type of permit (e.g., commercial building): Other permits (©): ^ DOF/W HPA ^ COE Weeands ^ FEMA ^ Shoreline Management ^ Encroachment ^ Other ^ COE 404 ^ DOE Dam Safety ^ Floodplain ^ RockerylRetaining Wall ® Grading Other agencies (Federal, State, Local, etc.) that have or will review this Drainage and Erosion Control Plan: None Part.4--Proposed Project Descriptip_n What stream basin is the project in (i.e., Clover): Project Size, acres 4.12 Acres Zoning :......................... R-6 Yelm Creek On-site: Residential Subdivision: Number of lots..._....__ .........................._..._..._..__..... _. _. 29 Units Lot size (average, acres) .................................................... N/A Building PermitlCommercial Plat: Building(s) (footprint, acres) ............................................... 0.44 Acres Concrete paving (acresj........._.... _......_...._..........__._.... 0.28 Acres Gravel surface (acres)............_.... _....... _.__.. _..........._..._ NIA Lattice block paving (acres) ............................................... N/A Public roads-including gravel shoulder (acres)............ 0.25 Acres (oH-site) Private roads-including gravel shoulder (acres) .......... 0.33 Acres On-site impervious surface total (acres) ....................... 1.05 Acres Part 5-Pre-developed Project Site Characteristics: Stream through site (y/n) ......................................Yes Name.......__...__..._......._..... _.._........ Yelm Creek Shoreline Designation...... _ ................. Urban Type of feature this facility discharges to (i.e., lake, stream, intermittent stream, pothole, roadside ditch, sheet0ow to adjacent property, etc.): Spreader Trench GROUND Swales (y/n) ....................................................... ......... N Sleep slopes-steeper than 10% (y/n) ................ ......... N Erosion hazard (y/n) .......................................... ......... N 100-year Floodplain(yln) ...................... _............ ......... 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 [o facility including off-site (acres) ............ ....... 4.12 Acres Total on-site area tributary to facility (acres) ........................... ....... 4.12 Acres Design impervious area tributary [o facility (acres) .................. ....... 1.05 Acres Design landscaped area tributary [o facility (acres) ................. ....... 3.07 Acres Design total tributary area to facility (acres) ............................ ....... 4.12 Acres Enter "1" for type of facility Wel Pond detention ............................................ ....... 1 Wet pond water surface area (acres) ................. ....... 0 Dry pond detention ............................................. ....... 0 __ Underground detention ....................................... ....... 0 Infiltration pond ................................................... ....... 0 Drywell infiltration._............_..._ .......................... ....... 0 - _-- Coalescing plate separator ................................. ....... 0 _ Centrifuge separator (Vortechs 2000) ................ ....... 1 Other .................................................................. ....... 0 Ou[le[ type (enter "1"for each type present): Filter ............................. _....... _...... _.......... ................. 0 Oil/water seParator ................................... ................. 0 Single orifice ............................................. ................. 0 Multiple orifices ......................................... ................. 0 Weir .......................................................... ................. . 0 Spillway ..................................................... ................. . 0 Pump(s) .................................................... ................. 0 _ Other (Spreader Trench) .......................... ................. t Part 7 -Release to Groundwater Design percolation rate [o groundwater (if applicable) ..........................................N/A Part S- Release to Surface Water (if aoolicablel Prior to entering [he 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. II. PROJECT ENGINEER'S CERTIFICATE I hereby certify that this Drainage and Erosion/Sediment Control Report for the SAMANTHA 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 [his community far professional engineers. I understand that City of Yelm does not and will not assume liability for the sufficiency, suitability, or performance of drainage facilities designed by me. ~~. 37399 _ ~l) _..__. Date III. DRAINAGE REPORT Section 1 -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 Coa(es Street in Section 19 of Township 17N and Range 2E. The project involves the creation of 29 residential units on 0 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 Conditions Appendix Acontains apre-developed hydrology map showing the site as it exists today. As can be seen from [hat 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 aright-of-way dedication to the City of Yelm. Although the overall parcel is significantly larger than 4.12 acres, the western portion of the site is being segregated through a Boundary Line Adjustment process and sold [o 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 [he 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 considered 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 [his 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 a[ Thurston County Health Department and the Department of Ecology were searched in order to locate wells and septic systems that may be located within the setback distances from the stormwater 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. .. , _,UG- ~2^ ,., ~~ _ Section 5 -Fuel Tanks Records at Thurston County Health Department and the Department of Ecology were searched in order to locate [he 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 three drainage basins (see Appendix A for Drainage Basin Exhibit), with a high elevation of 345 feet along the southwest corner of the site and a low elevation of 330 feet along the north and east sides of the project. For drainage basins #2 and #3 all impervious roads, sidewalks, and driveways will 6e routed to the ponds for treatment and detention. All roofs will be provided with a storm drainage stub connecting to the centralized storm drainage water quality and detention system, thus eliminating the need for individual infltralion systems on each lot. Drainage basin #1 will convey a small portion of storm water for Crystal Springs Road to catch basin #12 then via a 12" diameter pipe to an existing ditch along the west side of Crystal Springs Road. Drainage basin #1 discharges to the road side ditch, instead of the project detention system due to elevation /grade issues. 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 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 pads 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 [he project will total 45,738 square feel, or 1.05 acres. The proposed storm drainage system, designed to comply with the 1992 DOE Stormwater Management Manual for the Puget Sound Basin, will include a detention pond at the eastern portion of the project site. This storm pond has been sized to receive runoff from the site. The developed 2, 10, and 100-year storms have been estimated using the SBUH methodology using [he StormshedOO 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 for drainage basins #2 and #3. 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 8,590.28 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. Drainage basin #1 will discharge to an existing ditch on the west side of Crystal Springs Road. A hydrologic analysis of the developed conditions has been completed using StormShed software and the SBUH methodology using a Type 1A hye[ograph_ On-site soil has been classified as Spanaway Recessional Outwash Sand and Gravel as a result of the on-site soil exploration completed 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, infiltration on a large scale is not recommended due to the presence of a high water table. Instead a detention system is proposed. The results of the detention analysis, showing the expected runoff values from the impervious areas contributing to the WQ and detention systems, are tabulated below: Even[ Pre-Develop Flow cfs Developed Flow (cfs) Attenuated Flow cfs) 2- r124-hr .1960 60% -.0980 .6074 .0990 10- r124-hr .4183 .9366 .4179 100-yr/24-hr .6667 1.2448 .6660 The detention pond sizing was performed utilizing the rates presented above and is presented in the Appendix 8. The appendix contains the hydrology calculations as well as pre and post-development 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 governing 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 body to inspect the stormwater facilities. The agreement also makes provisions for the governing 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 borne by the property owners, their heirs, successors, and assigns. Section 11 -Property Owners Association Articles of Incorporation All residential subdivisions shall form a Homeowner's Association for the purpose of assigning responsibility and liability for [he operation and maintenance of stormwater facilities jointly serving lots within the subdivision. The association is no[ required for facilities that serve a single property owner. Articles of Incorporation shall be developed for the association and submitted to the governing body prior to final project approval. Section 12 -Other Permits or Conditions Placed on [he Project Building Permits will be obtained to construct the buildings. Section 13-Bond Quantities and Declaration of Covenant These items will be supplied after [he first review of this plan set. IV. EROSION CONTROL PLAN ~., c~- h,.,c= :.., - -- -- 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 construction entrance, shall be installed in accordance with this plan and the details shown on the drawings. More specifcally, [he following construction sequence shall be observed: Construction on this site shall be conducted substantially in accordance with the construction sequence described on the plans and in this erosion control 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. 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 [0 6e disturbed. d. Call for inspection by the project engineer. e. Clear and grub site per plans and specifications. f. Install erosion control measures as required. g. Rough Grade site and 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 perform as temporary sediment traps. Protection of offsile properties against sedimentation is an absolute necessity. Additional measures may be required to provide full protection of downstream areas. Additional measures may include, but are not limited lo, 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-of-way becomes excessive. If the entrance mat becomes filled with dirt, i[ will be refurbished by dislodging [he riprap and reconstructing the pad. Alternatively, new material will be added to the pad to provide 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 inseds 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 [he material and will be replaced if defects are identifed. ~n'ti,. , ~~_ __. , .., .~,_ Section 3-Permanent Erosion Control and Site Restoration There are no permanent retaining walls, energy dissipaters, geotextiles, 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 o[henvise 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- Geo[echnical Analysis and Report Existing slopes in the area of the stormwater ponds are at a maximum o(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 [raps, 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 findings as to performance 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 [he responsibility of the Contractor. As a minimum, 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 6e 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 activity to ensure that no erosion or sediment transport occurs. Trenching spoils will be treated as other disturbed earthwork and measures will be taken to cover or otherwise stabilize the material, as required. _... .... _~.i .... _„=rz APPENDIX A -Vicinity Map & Drainage Exhibits VICINITY MAP ~~ ~ ~~ o -~ z o cogr ~ o z /i c~sST ~ ~ SITE ~, ~ X / ~~SF o ~ ~ ~, ~ ~ ~~ ~ ~~~ ~ '"Fi ~~ ~ / ~qb 5~ A ~ ~ ~ ~~Fsr ~~ ~ ~~~~E ~~ ~a V ~ ~5~ %~, / ~ , ~ / ~/ ~ ~ / /~ ~ ___ ,. __ _,- z,~_. _~- t / ~ ~ / / ~ i ~ / ~~ / ~' / / n' ~/~1/ 'SCC~Wfpl..~I ~'l t~ !!l~Q~ C 4 ~~.- : ~;. ;. \ ~R ~~ \\\~\~ `~ ~ ,, } . ~ ~ ~'i .i b ' ~C ~ ~ ~ ~, ~~ ,~ c ~ ~ ~ , I I ~ , 1 ~' ~ ' 1 ti 1 ~ ~ ~~ ~ m a ~ ~ ~ ~ ~ ~ ~ / !~ 3 z a m H _. ,~, h nLi _. .,..., _'_ ~ i;~' li b L i~~ ~ ^ Q I ~~ ~~ ate, E ~ J I !- II J~1 ~ ~ g ~ F `~ ~~ ,I. y ', '~ i y y~e R ~ i ~~6 Y ~ . ~ " 4.1 ' I 1 '1ypY1, ~ I ~! !~ < / L:`~ - ' ~ f« ~ ~~~ e~ n,< -- ~ ~- ~~ ~ i ~, \~; ~"j ~,~ ,~ \ f r ~ ~~~ ~ ,~' ' ! ~ / hl I. ~"~ ~ N ~~ H~ ~_ o' :a g~ v ~m y _.. N a ~a ~~~o v c~ m __ ~.- z~,~_ ~,~ ~~~ __ °°E< r` , `~ ~e .~ '~ ,~ s ~ ,. --- ~ `~~, d i \~6~ ~~ ,~ \ % om ~ m , ~` \\ °R / ~~ o ~' £" 6 ~; 4 ~~0 ~9 x AI \\9 \ \\ '1 ;e ~/i ~~ _ i"i~F i ~ 9 z n ;. ~ e .. a <, Federal Enrereency Management Agency '<,a~` Wuhin~ton. D.C. ?04T_ D) September 11, 2W7 Mft. DF\xIS P>6ER C'.\SE NO.: 09-10.0690A GEOMATICS LAFD SURVEYING COMMUNITY: CITY OF Yb:LN. TFiCRSTOrv COUNTY I'.O. 60X 255!1 W Atitf INGTOS YELM. ti'A 9859]-2550 COMMUNITY NO ~ A0310 DEAR MR. RARER This is in reference to a request Thal the federal Emergency Mnnvgement Agency (PES1A) determine if Ibc prnpeny described in tlm enclns<d documem i locoed .rithin an idmaifieJ Special Flood Havrd Area, We urea that would he inundated h}' the Rood having a 1-perecm cbana of being equaled or exceeded in ans' given year (bsse flood). on the efTective National I'Ieud Insurance Pmgrem (h'FIPI mop. Using the information submitted and the eticetire NF1P nmp, oar determination is shown on the ennebed Letter of Map Amendment (IAMA) Determination Document. This determination documem provides additional information regarding the effective NFIP mug. the Icgvl description of the propem end nor determination. Additional documents ere enclosed wit ich pmTide information regarding the subject property and LOMAs. Please see [he Lisr of Enclosures Ixlmv m determine which documenh are enclosed. Pther attaehmenls specific to this request Imp he included au referenced in tho Detenninalion.'Comment duntment. If you have am~ questions alwut this letter or am of the enclosures, please contact the FEMA Map Assistance Cenfcr toll tree et (8]]) 336-?627 (87]-Ff MA .NAP) or by loner addressed to the Frdeml Emergency Aiamagement A_enq. 3601 Eisenhower .Avenue. Suite 130, Alexandria, VA 22364439. Sincerer William R. Rlaamn )r., CI'M, Chief I'ngineering A1anagemew Section Mitigation Dimctorate LIST OF EMiCLOSURES: LOMA DETERMINATION DOCUMENT IRE41p\'AL) m: Snam'COtmnrnlwc:Jth'.2FIP Conrdinamr Communip Afap Repository Region Page 1 of z IOate: Seprem0er 11, 200] Casa No.: 0]-00-0698A LOIAA 7 Federal Emergency Management /agency `:° Jcaehmglorl. [>.C'. any„ LETTER OF MAP AMENDMENT DETERMINATION DOCUMENT REMOVAL COMNU NItt ANO MAP PpNF11NF00.MATIDN LEGAL PROPERTY DESCRIPTION Cltt OF YELN, TXURSTON A poriipn of Sedron 19. Township tT Nprth. Range 2 East COUNTY. WASHINGTON WJldlnefte MenOlan as Shpvn on N¢ BOUntlary Lrne Adjusimenl Map amNed as Dowmenl Na 3935819. m the Ofllce of the R¢mltlel, C~~Itt Thurston CpunN. Washington T]I¢ PORion of gpPeM is more palliwlatlY tlestnhetl hY the PoIA 'rig COYYUNNY NO.: S]03t0 mares am pohnaa: NUMBER: S]0]t0000ta AFFECTED MAP PAMFL GATE: N1&1949 FLOODING SOURCE YELM CREEK APPROXIIMTE LAtINUE6LGNG1T11OE pF PROPERTY: i69a5.-IS1605 WVRCE pF LAifl LpXG: PREG510N MAPPING STREETS ).p DATUM: NAON DETERMINATION OUTCOME 1%ANNUAL LDWESi LOWEST CHANCE ADJACENT LOt LDT BLCCq SVRONIyON STREET REMOVED FROM FLOOD FL000 GRADE ELEVATION SECTION THC SFrvA ZONE ELEVATION ELEVATION INGV020) NGVp 25 (NGVD P9 'A2 Crysdl Springs Portion of % 330.2 W 3?44 -~ ]30.2 M J284 Raga NW ProFCrly IslaOetl) Icet feel Special Flooa Nauea Ana (SFNpt -Rte SFHA Is an area Thal wouM be Inundalea by Ne floo0 baring a LPerwnt Ulanca of pemg ualN m ei ar ease flo ADgRONAL fANSIOERAT10N5 PIease.eMbmee rule Sedan on AnaTnMMIk.lM aaanrow wnveenlbns tislm celm+.l LEGN. pROPERIY pESCRIPTION PORTIONS REMAW W TIE SFH4 Thn aaomwM provNSS aM fetlenl Emergerlry Management rtBanryY tlobrminallon 2gaNVq a npunsl b Map R ement (m a e the progeny tleecrippa aWm. Using Ipe inlprmilbn EoOmlHpa anE lee elhctive NafwnM Glood In a lNFlpt mag we Mve PIOU/am JelerminM INI Me Eeeulpetl poMOn(el of IM propenyllest IOart riot Iom1eE In the SFHA, a aMa py IM 5ootl MNnp a 1 pertenl a Gientt al temp epwNtl o cee0e4 in any given year box flontll Thia tlowment a Ma Ipe alleUive NFIP map l0 2 w the supietl propNy h T Ne $FNA looletl rn e1bUM NFIP m : IMnlore Ne Fepeeal m elery naW in .ce repuhemenl area net apply Nawemr, 11¢ bMer Iraq be oppon to a Ocoa in mOCrcemeM Ih Pruletl hs finanoal risk m re ban. A prebnM NN PoFry (pRPl6 aradatabdMkgs acalN OUlsgelle SFN0. lMdmapon apmnx piP amllvY Crew appY it entlessN Thk tlalennlMlion is paiea On a Ilona tlala prasenlly areiMple. Tne encbiep paCVmenls pro aeampnel Inlormallpn rpperping IIIH rminelbn. H YOU ha spy pveitmna apoul This aocumenl, pkase Canlad 0e fEMA Map ABeislance Lenlel loll ryes el IB]]I ]3&gfi3] (0]i~FENA MPPt or py letlnr aaaresiea m III¢ Fpaeeal Emergmry Manapemenl Aponq. 3601 Eiwnnowel Avenue, Suaa IJO. Ak[iMaa. VA Y230a~W39. b/.i~:. R /iC..~ /t- N9Yam R. 9brtlorr Jr_ CFM, CRN fnpaeeny Managemca Semen Milgalim dad _. _.. __. Pagv Z of Z Dare: September 11, 30p] Case No.' 0]-0o-0fi90A LOMA e,nvv." 1 ~- Federal Emergency Management Agency LETTER OF MAP AMENDMENT DETERMINATION DOCUMENT (REMOVAL) ATTACHMENT 1 (ADDITIONAL CONSIDERATIONS) LEGAL PROPERTY DESCRIPTION tCONTINl1ED) C061MENCING at the Northwest Comer of the NorNeas[ Quarter o! the Northwest Quaver, thence 501`02'02"E, 1322.01 fee[; thence 501`01'58"E, 1095 58 feet thence 501°02'DO"E, 192.08 feet to the POINT OF BEGINNING; thence N37°5743"E. 4].68 tee( thence N01°02'DO'lN, 531.32 feet, thence S56°1 T48"E, 3.07 feet) thence 528°oT43"E, 47.]7leef, Nenra 583°25'52"E. 14.161eet; thence N53"54'13"E. 14.49 feet; Menw NJO°d9'3]"E. 23.92 feet; thence 683"48'10"E, 21.]0 fe¢I; thence 531"14'32"E. 56.02 feet, Nance S36°14'02"E, 31.55 feel; thence 53490'24"E, 41.18 feet, thence 534°05'02"E, 46.]2 feet. thence 636°22'2SE. 4&5] Jeep thence S51°31'26"E, 47.44 teeq Nance 549°13'15"E. 23.55 feet: thence 507°52'2fi'W, 34.62 feel; [henw 640°45'47°E, 16.88 feet, thence 518°38'14'E, 32.01 feet thence 540°3P04'E. 4b 48 teat, thence 535°16'44"E. 2].28 feet; thence N81°t T28'E, 37.25 feeC thence 550°54'00"W, 236 ]6 feet, thence N01°02'00"W, 10.00 fee[ Nance 579°40'S4'NJ, 100.63 feet, thence SOt'02'00'E, ID.OO lee( (hence 579"40'54M/, 100 00 leer to the POINT OF BEGINNING PORTIONS OF THE PROPERTY REMAIN IN THE SFHA (This Atldi[ional Consitleration applies to the preceding i Proparty.j Portions of this property, but not the subject of the De[enninationlCOmment tlocument, may remain in the Special Flood Hazard Area Therefore. any suture construction or substantial improvement on [he property remains subject to Federal. StatelCOmmonwealth, and 1pCdl regulations for Ooodplain management. This allaUmenl prpnaex aEdilional inlormalron eegarmng tnia reaueal. n Yau nave any g~eal~one a Imcnmem. please wnbcl m Msy n e eemer t t f6a]1 9]63tii]IOIFfEM5 MPGi or Gy set@e aEOroxieE al ell~e M[aEeml Emeepency Management gyHKy, ]SOr E~senhmar Axanue, SWe 1Li. AlexarMia. `/F I3a'J~elle. 1M11Ram R. &anlm Jo. CFM, CHeI Erp'meevg MareOemeM Seclbn Milgalgn LMedW91a _. _. .. - ~.:_ 2.1°... ..__ w4Pn~`r l ~~o g Federal Emergency Management Agency r° ~ Washin ton, ll.C. 20.77? ADDITIONAL INFOR~fATIOV REGARDING LETTERS pF ;4L1Y .4A1END~fENT Wh<n making determinations on request for Letters of Map Amendment (LOMAs), the Utpartmenl of Homeland Securip's Federal Emergcmy Managcmcmt Agency (PENH) hoses iL+' detrnninstion on the flood hazard information available al the time of the determination Requesters should lx aware thn[ ^ooA conditions may change ornew information may be genemtcd that would supersede FE41A's damninadon. In such cases, the communip' will be informed by tenet. Requesters also should he aware that removal oC a propcny (parcel of land or sGUCmrtj from Nt Special flood Hazard Area (SFH.4) means FEMA has determined the properly is not subject m inwdation by We Mod having a 1-percent dunce ofbeine equaled or exceeded in any given year (brio Flwd). This does not. mean Iht property is not subject to older Rood hazards. The propcm could 6e inundated by a flood with a magnitude greater than the 6vc ^omf or by localized Rooding net shown on the tffective Naliorml FIoeJ Insurance Program (NFIP) map. The eRect of a LOMA is it removes the Federal requirement [or Ne lender to requve flood insuavice coverage for We property desmbed. The LOMA¢ nor a waiver of the wndi5nn Nay the property owner maintain flood insmance coveage for the property. On/r'the lender can waive the Flood imumnce purchase requirement because the lende[ imposed We requirement The properq' turner nmst renluev and reteisr a urirren w ter f om tlro lenArr 6ejore cance/irzg the police. Thz Irndcr may dmcrmine, oft its own as a business decisivq Nat itwishes to continue We Rood insurance requircmert to prorec[its financial risk on she loan Tbe LOMA provides FfiMA'a comment o¢ Ne mandator}' Rood insurance requvemums of the NFIP as Ncy apply to a panieutar property. A LOMA fs nut a bwlding pemtit, nor should ii be construed as such. Any' development, new construction, or substan4al improvement o(a property impacted by a IAMA must comply wiN all applicable State and local mteria and older Palatal criteria. IFa lender releases a property' owner (ram the flood insuavice requ'vement, and Ne prepeny owner decides to cancel Ne policy end seek a refwd, Ne NFIP will refund the premimn paid for the currem policy year. provided tha[no claim is pending or has been paid on the poticrJmivg Nc totem policy year. "Chepmpcrty owner mu t provide a written waiter o(Ne insurance requiremem Crom the lender to Ne property' insurance agent or company urvicing his or her policy. The agent or company will Ntn process the refund rcqutst. Even Nough sW<fures are not located in an SFHA, as mtation<d above, they coWd be Roodcd by a Rooding went wi W a greater magnitude flan the base Rood. In fact, more than ?5 percent of all daitns paid by the NF1P are for policies for s¢uchucs located outside Nc $FHA in Zones 6, C, X (shaded), orX (unshaded). More than one-fourth oCall policies purchased under the NFlPpromctewdwcs locarad in Nese zones. The risk to slnaarea Iveated outside SFN.4s isjus[ not as great as the risk to stmetums located in SFHAs. Finally, approximately 90 percent of all fedtmlh' dcdamd disaucrs arc cau~cd by Rooding, and homeowners insurance does not prmide financial protection Gom Nis Rooding. Therefore, FEMA encourages the widest possible covaragc uadtt We NFfP. U)M.AENC-1 APPENDIX B -Hydraulic Analysis PROPOSED DETENTION POND SUMMARY: e®~ogwurr~dm n~~nm ~.s~arersr __ ,.2D3o X15, 9E t4 POMD FOOD PIER o~er.~ ~ § ~ ~~ ~ d e ~m _.. _.. u 'MHA ROCS < .. __-_ residence time is sensitive to the shape of the inFlow hydrograph. The inFlow hydrograph is also of fundamental importance when designing an infiltration or filtration BMP as these 6MPs are sized based on a routing of [he in}low hydrograph through the BMP. The best solution at this time is to try to account £or subsurface Bow when estimating the time of concentration. For sites with low impervious cover, this will increase [he time of concentration, thus reducing the peak Bow rate and shifting the peak mie to a somewhat later time. Note [hat for BMPs which maintain "permanent pools" (o.g, we[ ponds) none oC the above coneems apply since the permanent pool volume is adequately predicted by SBUH. Flaw Contro[ Where a continuous runoff model is not available, it is necessary to use a modified SB[JH approach described in Volume I, Minimum Requirement # 7: Flow Control, "Interim Guideline". The modified SBOH approach approximates a design intended to achieve the Bow duration standard by adjusting the target peak flow standard, restricting other variables, and applying volume correction factor. The volume correction factor in Figure 2.1 is based on [he post development impervious cover and is necessary where the predeveloped condition is modeled as pasture. This werection factor is to be applied to [he volume ofihe BMP without changing its 1 w n, Z depth or the design of the outlet structure, thus an increase in surface area will result. ~ K 0 U 1 5 Q LL 1.4 Z - O U 1.3 -- _ ~ ~. ~ C ~ 1.2 1 _ . _ .. ~ ~.. 1.1 0 20 40 60 BO '100 SITE IMPERVIOUS COVER (% ~ Figure 2.1 Volume Correction Factor to be Applietl to Flow Control BMPS Based on Silo Impervious Cover Note that i[ is not necessary to apply the cortec[ion factor [o [he BMP volume for the muoff Veatmen[ storm. August 2001 Volume lll-Hydrologic Analysis and Flow Con[rolBMPS 2-5 _ _ nme ssesiro-rwmix tBYVaES CdFldIMMXI ucv~nmmeicvnnuiwVo ~ w.H.Ea ~ A f_ ~svunr ~~onw~wxnn scu ~rmen~mm _ .aa . . ~ ,~, ~,, f ~~ ramie A ~(I PLAN VIEW B - B SECTION A-A .m,.wrs».m:µ..~ w~mw.wE.ecm ~ ~~.,t.,~.w,~a.,~.a.~ am~artivmxx m i~~: PROPRIETARY INFORMATION - NOT TO BE USED FOR CONSTRUCTION PURPOSES wosamm...~..~.~,...w~.~..m...~..~wo~reaa~.~...~.om.a~..~do..ee.~.~. om. o.++ mMnwm[ais~s~eue~iw~e~w~rvamm~~i~n,+v~e~Oam~~rum~. iw srr~~®~. rv.e~emTeeuemw~eue W ma.~u~.nmrtm~r~i.r~w+~~rrm~a~vmueew wao^NN.~m~mv~. i GP. n. STANDARD DETAIL STORMWATER TREATMENTSYSTEM ~~A~ 5 VORTECHS®MODEL 2000 /al1PORICQq YOD~1010 R¢ PRE-DEVELOPMENT STORM EVENT SUMMARY Event Peak O (cis) Peak T (hrs) Hyd Vol (acft) Area (ac) Method Raintype 6 month 0.1444 9.00 0.1356 4.1200 SBUH TYPEIA 2 year 0.4295 8.50 0.3141 4.1200 SBUH TYPEIA 10 year 0.9233 8.17 0.6014 4.1200 SBUH TYPEIA 100 year 1.5382 8.17 0.9419 4.1200 SBUH TYPEIA PRE-DEVELOPMENT AREA SUMMARY Design Method SBUH Raintall[ype TYPEIA Hyd Intv 10.00 min Peaking Fac[or .484.00 Abstraction Coeff 0.20 Pervious Area (AMC 2) 4.12 ac DCIA 0.00 ac Pervious CN 87.16 DC CN 0.00 Pervious TC 54.03 min DC TC 0.00 min Pervious CN Calc Description SubArea Sub cn Herbaceous 4 O8 ac 87.00 Impervious surtaces (pavements, roofs , etc) 004 ac 98.00 Pervious Composited CN (AMC 2) 87.11 Pervious T C Calc Type Description Length Slope Coeff Misc TT '.. Sheet Smooth Surfaces.: 0.011 25.00 ft 20.00 % 0.0110 2 00 in 0.20 mm Sheet Dense grasses 0.24 480.00 ft 3.00 % 0 2400 2.00 in 53 83 mm Pervious TC 54.03 min r..:. Boa= .~. ,_ .~~e2 POST-DEVELOPMENT STORM EVENT SUMMARY Even[ Peak O (cfs) Peak T (hrs) Hyd Vol (acft) Area (ac) Method Raintype 6 month 0.3386 7.83 0.1078 1.3000 SBUH TYPEIA _... _. 2 year ' 0.5991 7.83 01922 1.3000 SBUH TYPEIA _._ __ . 10 year 0.9235 7.83 02999 13000~SBUH TYPEIA 25 year 1.0844 7.83 03539 13000 SBUH TYPEIA 100 year 1.2448 783 04079 13000 SBUH _._ __ .. TYPE1 A POST-DEVELOPMENT AREA SUMMARY __.... _ Design Method SBUH Rainfall type __ _. TYPEIA Hyd Intv 10 00 min Peaking Factor 484 00 __ .Abstraction Coeff __ 0.20 _... Pervious Area (AMC 2) 0.00 ac DCIA 1 30 ac Pervious CN 0.00 DC CN 9800 Pervious TC 0.00 min DC TC 0.56 min Directly Connected CN Calc Description SubArea Sub cn Impervious surfaces (pavements, roofs, etc) 1 30 ac 98 00 DC Composited CN (AMC 2) 98.00 Directly Connected TC Calc Type Description Length Slope Coeff Misc TT Sheet Smooth Surfaces.: 0.011 30.00 ft 10.00 % 0.0110 0 00 in 0 00 min '.. Channel (interm) Concrete pipe (n=0.012) 200.00 f[ 2.00 % 0.0120 0.56 min Directly Connected TC 0.86min _.. _. ..... ....... ____ _. HYDROGRAPH PLOTS PRE 8POST-DEVELOPMENT 2 YEAR HYDROGRAPH Start of live storage: 330.00 f[ Even[ Mach O (cfs) Peak O (cfs) Peak Stg(ft) Vol (cf) Vol (acft) Time [o Emp[y 2 year 0.0980 0.0990 332.1232 2865.71 0.0658 39.33 2 year Hydwgiaph Plot os - ', ~, ,R wa,t?-rear'.. - .-_,_._ X04-' ', _.. ;_-,-_,- ,__; _:_ -__,__, _. X03 _.:_ _1__',__ .__. __'- r____. _' 01 0, .- rv rv n a ~n m r r m ~ Time in Hours' f ~ ~ rv rv rv rv rv rv PRE &POST-DEVELOPMENT 10 YEAR HYDROGRAPH Start of live storage: 330.00 tt Event Match O (cfs) Peak Q (cfs) Peak S[g (ft) Vol (cf) Vol (acft) Time to Empty 10 year 04183 04179 332.4328 347686 0.0798 42.17 '. 10 year HyJiogiaph Plot - __ - __,,_ rW~fPSt9U year a.a - _ ___ i4.~iflYeer out'.. ~i 0.6~.~ I '. o ~ 4 I I. I ', ', I - ', LL02 0, o .- rv m c ~n ~n e r w ~ oTime in Hours `' f rv rv rv rv rv rv __ __ _.. PRE &POST-DEVELOPMENT 100 YEAR HYDROGRAPH Start of live storage: 330.00 ft Event Mach O (cfs) Peak O (cfs) Peak Stg (ft) Vol (cf) Vol (acft) Time to Empty 100 year 0.6667 0.6660 332.8451 4377.40 0.1005 42.67 L^ 1 ~ _ g I I. ' '. '. ~s~ 100 year Hydrogiaph Plot.. _ __. _ __ .... - Y. ®Pos1100-y Ar- ®100 year ou[ 0 ~ o ~ rv ri w e m m r m m rn o Time in Hours ~ n ~ ~ DETENTION POND SUMMARY Descrip: Prototype Record Increment 0.10 ft Start EL 330.0000 ft Max EI 335 0000 ft Storage Node Pond Discharge Node Sp. Trench _____ Stage Storage Rating Curve _. __ 330.0000 ft 0.0000 cf 331.6000 ft'1952.6464 cf 330.1000 ft 88.6819 cf 331.7000 ft .2115.7571 cf 330.2000 ft 181.4756 cf 331.8000 ft 2284 1316 cf 330.3000 ft 278.4531 cf 331.9000 ft 2457.8419 cf 330.4000 ft 379 6864 cf 332 0000 f[ 2636 9600cf 330.5000 ft 485.2475 cf 332 1000 ft 2821 5579 cf 330.6000 ft 595.2084 cf 332.2000 it 3011.7076 cf 330.7000 ft 709 6411 cf 332 3000 ft 3207 4811 cf 330.8000 ft 828 6176 cf 332.4000 ft 3408.9504 cf 330.9000 ft 952.2099 cf 332.5000 ft .3616.1875 cf _.. 331.0000 ft 1080 4900 cf 332.6000 ft 3829.2644 cf _ __. _.. 331.1000 ft 1213.5299 cf 332.7000 ft X4048.2531 cf 331.2000 ft .1351.4016 cf 332.8000 tt :4273.2256 cf 331.3000 ft 1494.1771 cf 332.9000 ft .4504.2539 cf 331.4000 ft 1641 9284 cf 333 0000 ft 4741 4100 cf _ _... _.. 331.5000 ft 1794.7275 cf 333.1000 ft 4984.7659 cf Stage Discharge Rating Curve __._ 330.0000 ft 0.0000 cfs 332.6000 ft 0.5358 cts 330.1000 ft 0.0215 cfs 332.7000 ft 0.5932cfs 330.2000 ft 0 0304cfs 332.8000 ft 0.6447 cfs ___.. 330.3000 f[ 0.0372 cfs 332.9000 f[ -0.6919 cfs 330.4000 ft 0.0430 cfs 333.0000 ft 0.7357 c(s 330.5000 ft 0.0480 cfs 333 1000 ft 0.7768 cfs 330.6000 ft 0.0526 cfs 333.2000 ft 0.8156 cfs' 330.7000 ft 0 0568 cfs 333.3000 ft 0.8526cfs 330.8000 ft 0 0607 cfs .333.4000 fl 0.8879 cfs 330 9000 f[ 0 0644 cfs 333 5000 ft 0.9218 cfs 331.0000 ft 0 0679 cfs 333 6000 ft 0.9544 cfs 331.1000 ft 0 0712 cfs 333 7000 ft 0.9859cfs 331.2000 ft 0.0744 cfs 333.8000 ft 1.0163 cfs 331.3000H 0.0774 cfs 333.9000 ft 1.0458cfs' 331.4000 ft 0 0804 cfs .334 0000 ft 1.0745 cfs 331 5000 f[ 0 0832 cfs 334 1000 ft 1.1024 cfs 331.6000 ft 0 0859 cfs 334 2000 ft 1.1296 cfs 331.7000 R 0 0886 cfs 334 3000 ft 1.1562 cfs 331.8000 ft 0.0911 cfs 334.4000 ft 1.1821 cfs 331.9000 ft 0 0936 cfs 334 5000 ft 1.2074 cfs 332 OOOOft 0 0961 cfs 334.6000 tt 1.2322 cfs __ - _._ 332 1000ft 0.0984 cfs 334 7000 ft 1.2565 cts 332.2000 ft 0 1007 cfs 334.8000 ft 1.2804cfs 332.3000 ft 0 2874cfs 334 9000 ft 1.3037 cfs __ _._ _. 332.4000 ft 0.3926 cfs 335.0000 ft 1.3267 cfs __ 332.5000 ft 0.4696 cfs .335.1000 ft 1.3493 cfs 335 0000 ft 1.3267 cis 2 YEAR OUT-HYDROGRAPH SUMMARY Area 1.3000 ac Hyd Int 10.00 min Base Flow -- Peak flow 0 0990 cfs Peak Time 12.17 hrs Hyd Vol 0.1922 acft Time (hr) Flow (cfs) Time (hr) Flow (cfs) Time (hr) Flow (cfs) 1.17 0.0000 14.00 ____. 0.0985 ._ 26.67 0.0711 1.33 0 0010 14 17 0.0984 26.83 0.0701 1.50 0.0027 14.33 0.0983 27.00 0.0690 1.67 0.0048 14.50 0.0982 27.17 0.0680 1.83 0 0073 14 67 0.0981 27.33 0.0669 2.00 0.0101 14.83 __. __ 0.0980 _ 27.50 0.0658 2.17 0.0132 15.00 0.0979 27.67 0.0648 . -`. ~- ~.J3c .i. ^~ ~' c _.. _ _.. a -' _ 2 33 0 0165 15.17 0 0978 27 83 0.0636 2 50 0 0198 15.33 0.0977 28 00 0.0625 2.67 0.0221 15.50 0.0976 28.17 0.0614 2.83 0.0235 15.67 0.0974 28.33 0.0603 3.00 0 0250 15.83 0.0973 28.50 0.0591 3.17 0.0264 16.00 0.0971 28.67 0.0579 3.33 .__ 0.0280 _ 16.17 0.0970 28.83 ..............._.. 0.0568 3 50 0 0295 16 33 0 0968 29.00 0.0556 3.67 0.0309 16.50 0.0967 29.17 0.0543 3.83 0.0322 16.67 0.0965 29.33 0.0532 4.00 0.0335 16.83 0.0964 29.50 0.0519 4.17 0.0350 '. 17.00 0.0962 29.67 0.0506 4.33 0.0366 17.17 0.0961 29.83 _._. 0.0494 _. 4.50 . _ 0.0380 _ 17 33 0 0959 30 00 0.0482 4.67 0.0395 17.50 0.0957 30.17 ____. 0.0468 4.83 0.0411 17.67 0.0955 30.33 0.0455 5.00 0 0427 17.83 0 0953 30 50 0 0442 5.17 0.0441 '. 18.00 0.0951 30.67 0.0429 5.33 0.0457 18 17 ~ 0 0949 30 83 0.0415 _ 5.50 0.0473 18.33 _. 0.0947 ' __ 31.00 0.0401 5.67 0.0488 18.50 0.0945 31.17 0.0388 5.83 0.0504 18.67 0.0943 31.33 0.0375 6.00 00519 18.83 00941 3150 0.0360 6.17 0.0535 '. 19 00 0 0938 31 67 0.0345 6.33 0.0553 1917 00936 3183 0.0331 _. 6.50 .. _.. 0.0570 19.33 0.0933 32.00 0.0317 6.67 0.0588 19.50 0.0931 '. 32.17 0.0304 _.. fi.83 ..__ _ 0.0609 19.67 _ 0.0928 '. 32.33 0.0287 7.00 0.0627 19.83 0 0925 32 50 0.0271 7.17 __ 0.0648 __ _... 20.00 0 0923 32 67 0.0256 7.33 0.0670 20.17 _. 0.0920 ' 32.83 _ 0.0241 7 50 0.0692 20.33 0.0918 33 00 0.0228 7.67 0.0733 20.50 _ .. 0.0915 __ 33.17 0.0215 7.83 0.0794 20.67 0.0913 33.33 0.0186 8.00 00848 2083 00910 33.50 0.0161 _ 8.17 _. ... 0.0884 21.00 0.0908 33.67 0.0139 8.33 __ . 0.0902 21.17 0 0905 33.83 0 0120 8.50 0.0918 21.33 0.0902 34.00 0.0104 8.67 0.0932 21.50 ____ 0.0900 _ 34.17 _.__ 0.0090 8.83 0.0941 21 67 0 0897 34,33 0.0078 ~~, . ,3~ ,... ~ __. __ _. ,_ _~ 9.00 0 0950 21 83 0.0895 34 50 0.0067 9.17 0.0957 22.00 0.0892 34.67 0.0058 9.33 0.0962 22.17 0.0890 34.83 0.0050 9.50 0.0966 22 33 0 0887 35 00 0.0043 9.67 0 0970 22.50 0 0884 35.17 0.0037 9.83 0.0973 22.67 . 0.0881 _ 35.33 0.0032 10.00 0.0976 22.83 0.0878 35.50 0.0028 10.17 0 0979 23.00 0 0875 35.67 0.0024 10.33 0.0981 23 17 0 0872 35 83 0.0021 10.50 0.0983 23.33 0.0869 36.00 0.0018 10.67 00984 2350 00866 36.17 0.0016 10.83 0.0985 23.67 0.0863 _. 36.33 _. .... 0.0014 11.00 _._. 0 0986 23.83 0.0860 36 50 0.0012 11.17 0.0987 24.00 0.0858 36.67 0.0010 11.33 0.0988 24 17 0 0852 36 83 0.0009 11.50 0.0988 24.33 __ 0.0844 37.00 ___ 0.0008 11.67 _____ 0.0989 24 50 0 0835 37.17 0.0007 11.83 0 0989 24.67 0 0826 37 33 0.0006 12.00 0.0989 24.83 0.0817 37.50 0.0005 12.17 0.0990 25.00 0.0808 37 67 0 0004 12.33 __ _. __ 0.0990 25.17 0 0799 37 83 0 0004 12.50 0.0989 25.33 0.0789 _.. 38.00 0.0003 12.67 00989 25.50 0.0780 38.17 0.0003 12.83 0.0989 25 67 0 0771 38 33 0.0002 13.00 0.0988 25.83 0.0761 38.50 0.0002 13.17 0 0988 26.00 0 0751 38 67 0 0002 13.33 0.0987 26.17 0.0741 38.83 0.0002 13.50 0.0987 26.33 0 0731 39.00 0.0001 13.67 0 0986 26 50 0.0721 39.17 0.0001 13.83 0.0986 _ 26.67 ___ _ 0.0711 . 39.33 _. __.__ 0.0001 _._ . 10 YEAR OUT- HYDROGRAPH SUMMARY Area 1.3000 ac Hyd Int 10.00 min Base Flow Peak flow 0.4179 cfs .Peak Tme $.33 hrs Hyd Vol 0.2999 acft Time (hr) Flow (cfs) Time (hr) Flow (cis) Time (hr) Flow (cfs) 0.83 0 0000 14.67 0.1314 28.33 0 0776 1.00 0 0014 14 83 0.1286 28.50 0.0766 1.17 0.0040 15.00 0.1269 28.67 0.0756 1.33 0 0077 15 17 0.1261 28.83 0.0747 1.50 0 0121 15.33 0.1256 29.00 0 0737 1.67 00170 15.50 01253 2917 0.0727 1.83 0 0219 15 67 0 1237 29 33 0 0717 2.00 _.. 0.0242 15.83 ___. 0.1209 29.50 ____ 0.0706 2.17 0.0268 16.00 0.1192 29.67 0.0696 2.33 00296 1617 0.1184 2983 0.0685 2.50 0.0320 16.33 0.1178 30.00 0.0675 2.67 __ 0.0342 ... 16 50 0 1176 30 17 0.0664 2.83 0.0365 16.67 01174 3033 0.0653 .. 3.00 __ 0.0385 .. . 16.83 __ 0.1174 30.50 ___.. 0.0643 3.17 0.0404 17.00 0.1173 30.67 0.0631 3.33 00423 1717 01158 3083 0.0620 3.50 __ 0.0440 . _. 17.33 0.1131 31.00 0.0609 3.67 0.0457 17.50 _ 0.1114 31.17 _... 0.0597 3.83 0.0475 17.67 01106 31 33 0.0586 4.00 _... 0.0491 . 17.83 . __ 0.1101 ._ 31.50 __ 0.0574 4.17 _ 0.0508 18.00 0.1098 31.67 _.. 0.0562 4.33 0.0527 18.17 0.1082 31.83 0.0550 4.50 0.0544 18.33 0.1054 32.00 0.0538 4.67 0.0561 18.50 0.1037 32.17 0.0526 4.83 0.0580 18.67 0.1028 32 33 0.0513 5.00 0.0597 18.83 0.1023 32.50 0.0500 . 5.17 __ 0.0615 19.00 __ 0.1021 32.67 0.0488 5.33 0.0633 19.17 0 1007 32 83 0.0475 5.50 0.0650 19.33 . 0.1007 33.00 ___._ 0.0462 5.67 0.0667 19.50 0.1006 33.17 0.0449 5.83 0 0685 19.67 0 1006 33 33 0.0436 6.00 ___. 0.0702 ... _ 19.83 0.1005 33.50 0.0423 6.17 0.0720 2000 01005 3367 0.0408 _ 6.33 _.__ _. 0.0739 20.17 0.1004 3383 0.0395 6.50 _... 0.0757 20.33 0.1004 34.00 0.0381 6.67 0.0777 20.50 _. 0.1003 34.17 _ 0.0368 6.83 0 0799 20.67 0.1003 34 33 0 0353 7.00 __. 0.0819 20.83 0.1003 34.50 0.0338 7.17 _.. 0.0841 21.00 0.1002 34.67 0.0324 7.33 0.0865 21.17 0.1002 34.83 0.0311 7.50 ~ __.. 0 0887 .. 21 33 0.1001 _ 35.00 0 0296 7.67 0.0928 21.50 0.1001 35.17 0.0279 7.83 0.0990 21.67 0.1000 35.33 0.0264 8.00 0.3221 21.83 0.1000 35.50 0.0249 8.17 _. 0.4127 22.00 _.. 0.0999 35.67 0.0235 ........... 8.33 0.4179 2217 00999 3583 0.0222 8.50 0.4173 22 33 0 0998 36 00 0.0202 8.67 0.4104 22.50 _. 0.0997 36.17 0.0174 8.83 0.3887 22 67 0 0996 36 33 0 0151 9.00 0.3679 22.83 0.0995 36.50 0.0130 9.17 0.3429 _ 23.00 ._.. _ 0.0994 36.67 0.0113 _ 9.33 _. 0.3138 23.17 __ 0.0993 36.83 0.0097 9.50 0.2914 23 33 0 0992 37 00 0.0084 9.67 0.2640 23.50 0.0991 3717 0.0073 9.83 0.2397 23.67 0.0990 37.33 0.0063 10.00 0.2265 2383 00989 3750 0.0054 10.17 0.2146 24.00 0.0988 37.67 0.0047 10.33 0.2024 24.17 0.0985 37.83 0.0041 10.50 0.1952 24.33 0 0977 38 00 0.0035 10.67 _._ 0.1886 _ 24 50 0 0970 38 17 _ 0 0030 10.83 0.1809 24 67 0 0962 38 33 0 0026 11.00 0.1766 24 83 0 0955 38 50 0.0023 11.17 0.1728 25.00 0.0947 38.67 0.0020 11.33 0.1687 25.17 _.... 0.0939 _. 38.83 0.0017 1150 01664 25.33 0.0931 3900 0.0015 11.67 0.1637 25.50 0 0923 39 17 0.0013 _ 11.83 __ ___.... 0.1603 25.67 0.0916 39.33 0.0011 12.00 0.1583 25.83 0 0907 39.50 0.0009 12.17 0.1558 26.00 0.0899 39.67 0.0008 12.33 0.1524 26.17 0.0891 39.83 0.0007 12.50 0 1505 26 33 0 0883 40 00 0.0006 12.67 0.1480 26.50 0.0874 40.17 0.0005 12.83 _ 0.1447 26.67 0.0866 _ 40.33 _ 0.0005 13.00 0 1427 26.83 0 0857 40.50 0.0004 13.17 0.1417 27.00 '. 0.0848 40 67 0.0003 13.33 _ 0.1411 27.17 _ ' 0.0840 __.. 40.83 .. 0.0003 13.50 0.1408 27.33 00831 4100 0.0003 13.67 0.1392 __ 27.50 _. 0.0822 41.17 _. 0.0002 13.83 0.1364 27.67 0 0813 41.33 0 0002 14.00 0.1347 27.83 0.0804 41.50 0.0002 _._ 14.17 _ 0.1338 28.00 0.0794 41.67 0.0001 14.33 0.1333 28.17 0.0785 _ _ 41.83 _. 0.0001 14.50 01331 28.33 0.0776 42.00 0.0001 100 YEAR OUT- HYDROGRAPG SUMMARY Area 1.3000 ac Hyd Int 10 00 min Base Flow Peak flow 0.6660 cfs Peak Time 8.17 hrs Hyd Vol 0.4079 acft Time (hr) Flow (cfs) Time (hr) Flow (cfs) ___. ___. __ Time (hr) .___._ Flow (cfs) 067 0.0000 14.83 01719 2867 00784 0.83 '. 0.0021 15.00 0.1697 28.83 0.0775 1.00 0.0059 15.17 0.1686 29.00 0.0765 1.17 ___ 00113 15.33 01679 2917 00756 1.33 0.0181 15.50 0.1676 29.33 0.0746 1.50 0.0231 15.67 01653 2950 0.0736 1.67 0.0266 15.83 0.1615 29 67 0.0726 1.83 '.. 0.0304 16.00 _ 0.1593 29.83 _..__. 0.0716 2.00 0.0334 _. 16.17 _... 0 1582 30 00 0 0706 217 0.0366 16.33 01575 30.17 0.0695 2.33 0.0395 16.50 0.1572 30.33 0.0685 2.50 0.0424 16.67 0.1570 30.50 0.0674 2.67 0.0450 16.83 0 1569 30 67 0.0663 2.83 0.0475 17.00 0.1568 30.83 ....._......_... 0.0653 3.00 0.0498 17.17 0.1547 __ 31.00 _._... 0.0642 3.17 00520 17.33 0.1510 31.17 0.0631 3.33 0.0540 17.50 01489 3133 0.0619 3.50 0.0560 17.67 0.1478 ... _ ....... 31.50 .............._._. 0.0608 3.67 00579 1783 01471 3167 0.0597 3.83 I 0.0598 _ 18.00 _.._ 0.1468 31.83 0.0585 4.00 ' 0.0616 18.17 0.1445 32.00 _. _... 0.0573 4.17 0.0635 18 33 0 1407 32.17 0 0562 4.33 0.0655 18.50 0.1385 _ 32.33 ___.__. 0.0549 4.50 0.0673 18.67 0 1374 32.50 0 0537 4.67 0 0692 16.83 0.1367 32.67 0 0525 4.83 0.0712 19.00 0.1364 32.83 0.0512 5.00 0.0730 19.17 0.1341 _ 33.00 ___..__ 0.0500 5.17 0.0749 19.33 0.1303 33.17 00487 '. 5.33 0.0768 19.50 '. 0.1281 33.33 ~~ 0.0475 5.50 0.0787 19.67 _. 0.1270 .. 33.50 0.0461 5.67 0.0805 19 83 ~ 0.1263 33.67 0 0448 5 83 ... .... _... 0.0824 ._.._. ... .... 20.00 0.1259 33.83 0.0435 6.00 ... _. 0.0842 20.17 _ 0.1257 __. _. 34.00 0.0422 __. ___.. Tn4 R DG_ J24 -_. _ 6.17 00860 20.33 0 1256 3417 0.0408 6.33 0 0880 - 20 50 0 1255 34 33 0.0394 6.50 0.0899 _ 20.67 _ _.. 0.1255 34.50 0.0381 6.67 0.0920 20.83 0.1255 34.67 0.0367 6.83 00942 2100 01255 34.83 0.0352 7.00 00963 21.17 01255 3500 0.0337 7.17 0.0986 21.33 0.1255 35.17 0.0323 7.33 01144 21.50 01255 3533 0.0310 7.50 _. __ 0.2551 __ 21.67 01255 3550 0.0295 7.67 . 0.4032 21.83 0.1255 35.67 0.0278 7.83 0.5439 22.00 0.1255 35.83 0.0263 8.00 . .... ........... 0.6333 _.. 22.17 __..... 0.1234 36.00 0.0248 8.17 .. _ 0.6660 22.33 0.1197 36.17 0.0234 8.33 0 6561 22 50 0 1176 36.33 0.0221 8.50 0.6453 22.67 0.1165 36.50 0.0200 8.67 0.6277 22.83 0.1158 36.67 0.0173 8.83 06000 2300 01155 36.83 0.0150 9.00 __. 0.5745 23.17 0.1153 37.00 _. _.._. 0.0129 9.17 0.5442 2333 __ 01152 37.17 __ 0.0112 9.33 0.5065 23.50 0.1151 37.33 0.0097 9.50 0.4730 23.67 0.1151 37.50 0.0084 9.67 0.4389 23.83 0.1151 37.67 0.0072 9.83 0.4070 24.00 0.1151 37.83 0 0062 10.00 0 3782 24.17 0.1006 38.00 0.0054 10.17 0.3479 24.33 0.0999 38.17 0.0047 10.33 0 3216 24 50 0.0992 38.33 0 0040 10.50 __ : 0.3021 24.67 __ 0.0985 38.50 0.0035 10.67 0.2844 24.83 0.0977 ' . ............ 38.67 ................. _.. 0.0030 10.83 0 2598 25 00 0.0970 38.83 0.0026 11.00 0.2463 25 17 0.0962 39.00 0 0023 N.17 0.2366 25.33 0.0954 39.17 0.0019 11.33 _.... 0 2288 25 50 0.0947 39.33 0.0017 11.50 _ 0.2244 25.67 0.0939 39.50 0.0015 11.67 0.2200 25.83 0.0931; 39.67 0.0013 11.83 0.2149 26.00 0.0923 39.83 00011 12 00 0 2121 2fi 17 ~ 0.0915 40.00 0 0009 12.17 0.2085 26.33 0.0907 40.17 0.0008 12.33 0 2040 26 50 0.0899 40.33 0 0007 12.50 0 2014 ' 26 67 0.0891 40.50 0.0006 12.67 _ _ '. 0.1979 _ __.. 2683 .. _... 0.0882 40.67 _ 0.0005 _.. ..._....... .v -..-lice t1,.'S - - - _ ,.. 12.83 01935 2700 0.0874 4083 0.0005 13.00 0 1909 27 17 0.0865 41 00 ~ 0.0004 13.17 0.1896 27.33 0.0857 __ 41.17 0.0003 13.33 0.1888 27.50 0.0848 41.33 0.0003 13.50 _. 01884 27.67 00839 4150 0.0003 . 13.67 ... 0.1861 .. 27.83 0.0830 41.67 0.0002 13.83 0.1823 28.00 _. 0.0821 _ .. 41.83 0.0002 14.00 0.1801 28.17 00812 42.00 0.0002 14.17 0.1790 __ _ 28.33 _. __ 0 0803 42 17 0.0001 14.33 0.1783 28.50 0.0794 42.33 0.0001 14.50 0.1780 28.67 0 0784 42 50 0.0001 14.67 0.1757 28.83 0 0775 42 67 0.0000 Stage Discharge Rating Curve 330.0000 ft 0 0000 cfs 332 6000 ft 0.5358 cfs 330.1000 ft 0.0215 cfs 332.7000 ft 0.5932 cfs 330.2000 ft 0 0304 cfs .332 8000 ft 0.6447 cfs 330.3000 tt 0 0372cfs 332.9000 ft 0.6919 cfs _. __ __ . 330.4000 ft'0.0430 cfs 333.0000 ft 0.7357 cfs 330.5000 ft 0.0480 cfs 333.1000 f[ 0.7768 cfs 330.6000 ft 0 0526 cfs 333 2000 ft 0.8156 cfs 330.7000 ft 0.0568 cfs 333.3000 ft .0.8526 cfs _.. __... 330.8000 ft 0.0607 cfs 333 4000 ft 0.8879cfs 330.9000ft 0 0644 cfs $33 5000 ft 0.9218 cfs 331 0000 ft 0 0679 cfs 333 6000 ft 0.9544 cfs 331 1000 ft 0 0712 cfs 333 7000 ft 0.9859 cis _. __.. 331.2000 ft 0.0744 cfs 333.8000 ft 1.0163 cis 331.3000 fl 0.0774 cfs 333.9000 fl 1.0458 cfs 331.4000 ft 0 0604 cfs 334.0000 R .1.0745 cfs 331.5000 ft 0.0832 cfs 334.1000 ft 1.1024 cfs _ - _. _ _. .331.6000 ft 0.0859 cfs 334.2000 ft 1.1296 cfs 331.7000 ft 0 0886 c(s 334.3000 ft 1.1562 cfs 331 8000 ft 0 0911 cfs'.334 4000 tt 1.1821 cfs 331.9000 ft 0.0936 cfs 334.5000 ft t2074 cfs 332.0000 ft 0.0961 cfs 334.6000 ft 1.2322 cfs 332 1000 ft 0 0984 cfs 334.7000 ft 1.2565 cfs _... .'_. 332.2000 ft 0.1007 cfs 334.8000 ft 1.2804 cfs 332.3000 ft 0 2874 cfs 334 9000 ft 1.3037 cts 332.4000 ft 0 3926 cfs 335 0000 ft .1.3267 cfs __... a• ~__ - - __ _. .. _r_ '~',',o ~_ ;v 332.5000 ft 0.4696 cts 335.1000 ft 1.3493 cfs 335.OOOOft 13267 cfs SPREADER TRENCN_$UMMARY Descrip: Prototype Structure Increment 0.10 ft Start EL 328 0000 fl Max EI. 330 OOOO ft Appended on: 16:53:51 Monday, February 18, 2006 Record Id: Control Structure Descrip: Prototype Structure Increment 0 10 ft Start EI. 328.3400 ft Max EI 333 0000 ft Orif Coeff 0.62 Lowest Ori{EI. 326 34 Lowest Diam 1.8457 in Dist to next 2 5500 ft D2 3.3252 in Dist to next 0 8600 ft D3 _. 34863in Dist to next 1.0700 tt .. D4 .._ 4.0137 in Dist to next ~ 0.0000 ft Stage Discharge Rating Curve 328 3400 ft 0 0002 cfs 330 7400ft 0.1432 cfs ____.. 328.4400 ft 0.0292 cfs 330.8400 ft 0.1462 cfs 328.5400 ft 0 0413 cfs 330 9400 ft 0.2162cfs 328.6400 fi 0.0506 cfs 331.0400 ft 0.2681 cfs _ _. .328.7400 ft 0.0585 cfs 331.1400 f[ 0.3047 cfs 328.8400 ft 0 0654 cfs 331 2400 ft 0.3349 cfs 328 9400ft 0 0716 cfs 331 3400 ft 0.3614 cfs .329.0400 ft 0.0773 cfs 331.4400 ft'..0.3853 cfs 329.1400 ft 0 0827 cts 331 5400 ft 0.4073 cfs 329 2400ft 0 0877 cfs 331 6400 ft 0.4278cfs 329 3400 ft 0 0924 cfs 331 7400 ft .0.4471 cfs 329.4400 ft 0 0970 cfs 331 8400 ft 0.5644 cfs 329 5400 ft 0 1013 cfs 331 9400 ft 0.6266 cis ......... ..... _._.. ... 329,6400 ft 0.1054 cfs 332.0400 ft 0.6772 cfs 329 7400 8 0 1094 cfs 332 1400 ft 0.7217 cfs 329.6400 ft 0.1132 cfs 332.2400 ft 0.7621 cfs 329 9400 ft 0 1169 cfs 332 3400 ft -0.7996 cfs 330 0400 ft 0.1205 cfs 332 4400 ft 0.8347 cfs 330.1400 ft 0.1240 cfs 332.5400 ft 0.8680 cis 330.2400 ft 0.1274 cfs 332.6400 ft 0.8998 cfs 330 3400 ft 0 1307 cfs 332 7400 ft 0.9302 cfs 330 4400 ft 0 1340 cfs 332 8400 ft 1.0213 cts 330.5400 ft 0 1371 cis 332 9400 ft 1.1391 cis $33.0000 fh1.1897 cfs Licensed to: Petra Engineering, LLC APPENDIX C - Geotechnical Report r .v- ~ -- - _ _ - _ Gary A. Flowers, PLLC Geological & Geotechaical Consulfiug 19532 12`" Aveuue NE Shoreline, WA 98155-1106 August 4, 2006 Project No. 06-079 Pacific Frontier, LLC 111 5th Street NE Aubmn, WA 98002 Attention: Mr. Jack Long Subject: GeologicaVGeotechnica] Assessment Crystal Springs Property Crystal Springs Road NW & Edwards Road NW Yelm, Wahingon 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 Yehn, Washington. It is our understanding that the property will be developed to support single family residence lots. Site layout or grading plans were not available az the time of this report. The purpose of our site evaluation was to document existing shallow soil and ground water conditions on the property, and to provide geo[echnical design recommendations for constmetion of the proposed improvements. EXISTING CONDITIONS The subject site is an irregulaz triangulaz shaped pazcel measuring approximately 4.1 acres. The west side of the site slopes down from the adjacent road elevation to a lower flat azea occupying the majority of the property with a slight slope to the northeast. Total elevation change across the properly was on the order of 20 feet. A single story residence and attached garage are located on the southwest wmer of the site. Primary vegetation is field grass with a few shrubs and bushes. Several fruit trees and deciduous trees were located along the western side of the property. A small stream bounds the property on the east side. A utility easement with fiber optic lines bisects the property m the east-west direction. 77tere 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. _ Gary A Flowers, PLLC 1933212'°AVrnuc NG Shorelice, Wsshingbn 98153-1106 206-61'/-t64a Crysta[Springs Property GeologicaUGeofechnical Service Report Yelm, Washington Subsurface Sail and Ground Water Conditions Ia order to chazacterize the shallow subsurface soil and ground water conditions on the properties, a series of 8 subsurface exploration pits were completed using small track-mounted excavator provided by the client. The explomton pits pemutted direct, visual observation of the subsurface soils on the property. The exploration pits were logged by a licensed geologist and immediately backfilled. T1re exploration pit locations are shown on the site and exploration plan attached to this report. The exploration pits revealed that the site was underlain by Spanaway recessional outwash sand and grnvel. Minor fill soil was encountered in the southwest corner of the property. The topsoil layer was very non-uniform across the property. Little [o 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 gravel. The topsoil was loose, dry, dazk brown, &ne sandy silt loam. The upper 4 to 5 fee[ of EP-8 consisted of loose, dry, brown, gravelly sand with some silt and construction rabble. This material was fill soil of unlmown origin or age. Under the fill or topsoil layers in all of the exploration pits were Spanaway recessional sand and gravel deposits. The recessional outwash was deposited from fluvial processes during the retreat of the Vashon stade of the Fraser glacial period about 10,000 years ago. Infiltration into this lout is typically moderate to rapid. Tire ou[wash sediments wnsisted of loose [o medium dense with depth, dry to damp, brown or gray-brown, sandy grnvel and gravelly sand with minor silt. ORcn the sediment layers contained a significant cobble and boulder content indicating a high energy deposilional environment. The outwash deposits extended below the termination depths of all of our explorations at 5 to ] 0 feet. !n EP3 and EP-7, 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 higlily overgrown by shrub and blackberry vegetation. 1Lere was no evidence of erosion anywhere on the pazcel 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 EP3 and EP-7 at roughly the same elevation, about 8 to 9 fee[ below ground surface. 1'he ground water likely represents the local water table for this azea. The ground water elevation will vary with the time of year. Gary A Flowera, PLLC. 1953212m Avrnue NE Shoreline, Waffiingon 98155-1106 206-61]J6Cp Crystal.Springs Property Geological/Ceolechnical Services Repan Yelm, Washington Seismic Hazards Generally, there aze four types of potential geologic hazards associated with large seismic events: 1) surficial ground rupture; 2) seismically induced landslides; 3) liquefaction; and 4) ground motion. The potential for each of these to impact the site is discussed below. A few known fault zones occur m the Puget Sound region, however none are currently known in the Yelm area. Fault zones in the Puget Sound region aze currently being studied by the United States Geological Service (USGS) and have been determined [o be active and capable of producing large earthquakes. Much is still to be teamed 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 ground 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 topographic relief, it is our opinion that the potential risk of damage to the proposed stmcture, by large scale seismically induced landsliding, is low. Based on the density and grain 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 stmtigraphy, stmctural design of the project should be consistent with 2003 Grternatlona[ Building Code (B3C) 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 [hc site may be problematic for structural development and should be removed firm 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 to be abandoned according to Washington State Dept. of Ecology (DOE) standards. A well abandonment record will need to be filed with DOE and as such, a licensed well driller should be contracted to perform this work. Cary A. Flowers, PLLC. 1953212~ AvmuelJ6 Shortlinq WazRinglon 98155-1106 206-01]-]6C0 Crysml Springs Property Ceo/ogicaUGeWechnical Services Report Yelm, Washington Site Grading The existing vegetation on the site shall be removed from all areas planned m 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 structural fill wilt be required to develop the planned property. Stmcnual fill is non-organic soil that is neaz opthnum moisture content. The fill soil must be placed in maximum 8-inch loose lifts with each lift being wmpacted to a dense, non-yielding condition prior to installation of the succeeding lift. 1'he moisture content must be near enough to optimum moisture content to allow the fill to achieve the required compaction. Compaction effort must be applied to acltieve a minimum of 95 percent of the modified Proctor maximum dry density per ASTM:D-1557. Jn addition [o being monitored by a representative of this firm, the placement and compaction of stmctural fill should be tested using a nuclear densometer to verify that suitable compaction is being obtained. In the case of utility trench backfill, 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 fee[ beyond dre location of perimeter footings or pavement edges before sloping down at a maximum angle of 2H:1 V. It should be me responsibility of me contractor to maintain safe slope contigumtfons since the contractor is continuously on-site. As is typical with earthwork operations, some sloughing and raveling may occur and cut slopes may have m be adjusted in the field. It may be necessary to cover the sides of temporary slopes with plastic or otherwise protect them from the elements to minimize slougbing and erosion. For estimating purposes, we anticipate that temporary, unsupported cut slopes can be madc at an inclination of 1.SH:1V (Horizontal:Vertical). Pemranen[, unsupported cut or structural Sll slopes should not exceed a gradient of 2H:1V. Permanent, non-stmctural fill slopes should no[ exceed a gradient of 4H:1 V. Foundation Recommcnda6ons The planned residences may be se[ to bear on documented structural 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. M increase of one-third may be used for short-term wind or seismic loading. Perhneter footings for the proposed structures should be buried a mittimum of 18 inches into the surrounding soil for frost protecfion. Settlement of footings placed as detailed herein shomd be less than I inch between comparably loaded foundatoas. However, foundations placed on disturbed soil may result in increased settlement. Steps in the foundation grade are acceptable Gary A Flowers, PLLC. 19532121°AVmue NO SM1melinq WvAingtoo 98155-IIOfi 206-0gA640 Crysml Springs Property Gea/ogicaUGeotechnical Services Report Yelm, Washington provided that none of the foundadons aze set to bear adjacent to the step. A 1H:] V load line extending down from the edge of [he foundation must no[ daylight on a cut slope. All foundation excavafions should be inspected by a representative of this fiml, prior to concrete placement, to verify that the design bearing capacity of the soils has been attained and that constme[ion conforms [o the recommendations contained N this report. 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 atmetuml fill compacted to a dense, nonyielding condition to achieve the passive resistance provided below. The stmctuml fill must extend horizontally outward from the embedded portion of the foundation a distance equal to at least three times the embedment depth over which the passive resistance is applied. We recommend the following design parameters. • Passive equivalent fluid = 250 pct • Coefficient of friotion = 0.40 The above values are allowable and include a factor of safety of at least 1.5. Floor Support Recommendations Slabon-grade floors should be set to bear on undisturbed native soils or structural fill in a fvm, unyielding wndition. A capillary break layer consisting of 4 inches of washed pea gravel and a heavy duty (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 grovel, if free of silt, may also be used as a capillary break layer. if [he vapor barrier becomes compromised in any way during wnstmc[ion i[ should be replaced or an additional layer added. penetrations through the vapor bamer should be wrapped and taped. Site Drainage All smrm water mnoff from impervious surfaces should be collected and piped into an approval storm water drainage system. Individual lot infiltratien trenches or dry wells would be au option for this site. Footing drains are Likely not needed far this site provided the foundations aze placed atop the clean sand and grovels encountered in our explorafions. If footing drains aze utilized they should consist of rigid, perforated, PVC pipe surrounded by washed pea grovel. The level of the perforations m the pipe should be set approximately at dte bottom of the footing and the drains should be constmcted with sufficient gradient to allow gravity discharge away from the buildings. Footing drains that will have more than g feet of backfill should be constructed of schedule 3034 or better sewer grade pipe m minimize potential for collapse. Roof and surface runoff should not discharge into the footing drain system, but should be handled by a separate, rigid, tightline drain that discharges into an approved storm water conveyance system. In planning exterior grades adjacent to walls should be sloped downward away from the structure to achieve surface drainage. VeryA Flowers, PLLC. 195311216 AVrnuc Nt Shmelinc, Washingm 98155-1106 ]abpir- i6G0 Crystal Springs Property GeolagieaUGeotechnical Services Report Ye/m, Washington Due to the high Bound water table encountered in several of the explorations, a large scale infiltration pond may not be suitable for this site. Additional in-sim testing and Bound water modeling analysis should be performed to evaluate for Bound water mounding if an infdtmtion pond is to be utilized. However, individual lot infiltration systems are suitable for the residential properties. For roadway nntoff shallow infiltration ditches along the roadway may be an 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 ow exploration pits would be classified as sand per the USDA Textwa] Triangle. Per the Dept. of Ecology's Wes[em Washington Storm Water Manual, these materials have an allowable short term infiltration rate of 8.0 inches per how and an estimated long term infiltration rate of 2.0 inches per how with a correction factor of A. Due to some variability of the sediments on this site, and the relatively high water table, it is ow opinion that the higher correcton factor is appropriate and a maximum design rate of 2.0 inches per how should be used for this site. The design engineer should take this information into account during the design process. The infiltration facilities should be developed in accordance with requirements of the local jurisdiction for storm water runoff. SUMMARY Based on ow site reconnaissance and subsurface explorations the site appears to be suitable for the proposed development provided the recommendations presented herein are properly implemented. We recommend [hat we be retained to review those portions of the plans and specifications that pertain to Boding or foundation installations to detemrine that they are consismnt with the rewmmendations of this report. Construction monitoring and consultation services should also be provided to verify that subsurface conditions aze as expected. Should conditions be revealed during constmction that differs from the anticipated subsurface profile, we will evaluate those conditions and provide al[emative recommendations where appropriate. Field construction monitoring and observation services should be considered an extension of this initial geotechnieal evaluation, and are essenfial to the determination of compliance with the project dravvtgs and sped&ca5ons. Such activities would include site clearing and Boding, subswface drainage, foundations bearing and till placement and compaction. Gary A. Flowers, PLLC. 1953212°Avmue fJE Shoreline, Washington 98155-1106 206AI]-]640 _ _ _ C'rysral SprinFw Properly Gttnfogiaal/Geotechnicrtl Swv~iovs Report ~~ Yelm. H'arfiingron Qur findings and recommendations providyd m this rt-pnn were prepared in accordance with I generally accepted principles of engineering geology and gco[cehnical engineering us practiced in the Puget Snund aria at the time this report way submitted. We make no other warranty, either ~~, express or implied. 'I Sincerely, EXPIRES 11-28 Iamey S. 6attennann, P.E., L.G. Geotechnical Engineer Attachments: Site Plan Appendix A - Exploration Pit Lngs Gen' A. Pluwcrq PLLC. ~~ 195812°Avcnoc RL tiMvctiro. Wwainp~m 98155-1106 2nG-111-)(Ap ~~ ___ Cary A. Flowers, P.G., P.E.G. Engineering Geologist ~ I Ii ~ ~ , Y ~ :, { , . -.~j I l -- - 1 --- ,-, g J C C _. y C O O ~ O . W . c i c a ` O ~ a ~ ~ c t 1 i I o v c z z° ' ~ .: . .a S C`-o - ~ ~ U UL l~ . I ~ o - O ~ ' I [L _._. _ L . ___ W m° y `~ c3 ~ ~ ~ . ~ I X c] O ~,.- ~~: .....__ ............ . __. _.._ m U J O J U d 0 u_ 0 L. V Z 3'm ,off °'u~a ~,Q< o~~ V CI y' OI- C 'Q i, yn `o v ~ P h Ceologfca]/Gaotechnicol Services Report NW & Edwards RoadNW APPENDIX A EXPLORATION LOGS Gary A Flowers, PLLC 195)313^Avrnue fni Sho~eline,Wsshingtao9ffi55-1106 305d13.00y0 _.. EXPLORATION PIT LOG g Number EP-1 1 2 3 4 5 6 7 8 9 10 11 12 13 SPANAWAY RECESSIONAL OU7WASH Loose to medium dense, dry to damp, brown, sandy gravel with nibbles. in9weullm,e ~~ worewy ww, mgvre ryp~~q eenn9ynelyilf. anUpggmmt T,syare mllre$raiyrepesrvMine of rq,er lMrvs ana b®pen. xWpl~tt~*gM is Ne vswsee,p,NYmbYmnva of NO'natM pmunlM an prs Fg. ~'~ GARYA, FLOWERS, PLLC __. Crystal Springs Property Yelm, Washington July 10, 2006 __ _ ~, -. ,_ - _ _. t, °c - - _c3 EXPLORATION PIT LOG 6 Number EP-3 1 2 3 4 5 6 7 8 9 10 17 12 73 NISOUALLY LOAMY FINE SAND Loose, dry, dark brown, Tine sandy loam. SPANAWAY ftECE5510NAL OUTWASH Loose to medium dense, dry to damp, brown, sandy gravel and gravelly sand with cobbles and occaisional boulders. ~. n.. a,uaann nom. reoanm evanaew inum=vu a .aryais ^~Na9mem mq'=re wNn anreesan0ircatnn. vk xiu m, y; ao.ro».oun is ne ~re a ,.=mremm q wm or ~mo-maJa, rverem~m ~ na up.~ GARYA. FLOWERS, PLLC Crystal Springs Property Yalm, Washington Juty 10, 2006 EXPLORATION PIT LOG g Number EP-5 t 2 3 4 5 6 8 9 10 71 12 13 SPANAWAY RECESSIONAL OUTWASH Loose to metlium dense, dry to damp, brown, sandy gravel with wbbles. BOH aQ 5' Minor Caving No Ground Waler Seepage - - .•mb~~oy ~e..wn~.n.ewe.~a~= .~a.~.~n.,nmxv.m~wv~+.v mn.re ~ni..ress.nnrew.xmeez oromue,.nwwv,a.. vc..m„a +=^~~N~•w~en~ra ue..a a,,,mo..uno„ Wa~a~m.„.„d.w~.~m w, m: wa. Grystal Springs Property GARYA. FLQWERS, PLLC Yelm, Washington July 10, 2006 ...... _ _._ ,. -,~_~ :~.ac ~6 EXPLORATION PIT LOG o Number r EP-6 1 2 3 4 5 6 7 8 9 10 17 12 73 SPANAWAY RECESSIONAL OUTWASH Loose to medium dense, dry to damp, brown, sandy gravel with cobbles- BOH ~ 5' Minor Caving No Ground Water Seepage M weave .. worry a,arym. vtl l~0^~+-~M are vnyn pmx oM RUVOn Ne rnra~ aweplnewneAYq la Ike ux e, nevpaunm y meea of vnammtlm gemnm en euf oa.d~ Crystal Springs Property GARYA. FLOWERS, PLLC Yelm, Washington July 70, 2006 g Number EP-7 EXPLORATION PIT LOG NISQUALLY LOAMY FINE SAND Loose, dry, dark brown, fne sandy loam with trace gravel. 1 2 3 4 S 6 7 S 9 10 11 12 13 SPANAWAY RECESSIONAL OUTWASH Medium dense, damp, light brown, fine to medium sand. with some silt and trace gravel Medium dense, tlamp to wet with depth, brown, gravelly sand with cobbles and boulders. s~o.,,nau Q,wa,re,aaecmm rew~~~~„mv„aw,s ua tirc9 amwoeoa a me xyloreldy Iwo. mWIAhW sawwin ~nleryreNLNn. mpmze,lnp a,aly6la. a,q ~udpmo L rlSyue MnCRSYIY/ R0~^'etlre a oM Ilmez eM balun. N4will,q a~a ,~.~o-~ln .a aK ,Iw a, mre.oreml~. w ol~a a mr,,,,,ano~ w®=,lee a. a. ss. GARYA. FLOWERS, PLLC Crystal Springs Property Yelm, Washington July 10, 2006 _.. __ ..... .......