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18-101545_t cIrr of Federal Way Centered on Opportunity February 21, 2019 Mr. Ivan Stihari 3008 47th St. NE Tacoma, WA 98422 RE: STIHARI Folder # 18-101545-000-00-SF Dear Mr. Stihari: CITY HALL 33325 8th Avenue South Federal Way, WA 98003-6325 (253) 835-7000 www.cityoffederalway.com Jim Ferrell, Mayor Development Services has reviewed the third submittal plan set received January 25, 2019. The following comments still remain unresolved: 1. The "Drainage Facility" design calculations still have not been submitted. 2. Other than the proposed 14-foot diameter no other information has been provided on the "Drainage Facility" for instance depth, proposed media, proposed geotechnical fabric, and a design detail. We realize that these comments have been made before but the Development Services Department cannot sign -off on your proposed house until we have some assurance that the stormwater system has been designed in accordance with the 2016 KCSWDM. Sincerely, Cole Elliott, P.E. Development Services Manager cc: Andrew Norton, Plans Examiner Project File Day File \\CF WFILE IWpplicatioos\CSDC\PROD\docs\save\ 151050_78797_21093037.doc CITY OF ti. Federal Way February 28, 2019 Mr. Ivan Stihari 3008 471h St. NE TACOMA, WA 98422 RE: STIHARI Folder # 18-101545-000-00-SF Dear Mr. Stihari: CITY HALL 33325 8th Avenue South Federal Way, WA 98003-6325 (253) 835-7000 www. cityoffederalway. com Jim Ferrell, Mayor Development Services has reviewed your drywell sizing calculations. We make the following comments: 1. The drywell sizing calculations assume a coarse sand and cobble soil type. A review of the submitted soil logs provided on your site plan indicates a fine sand type 4 soil type. A fine sand does not meet the requirements of a drywell in accordance with King County Surface Water Design Manual (KCSWDM) Section C.2.2.2. 2. To resolve the conflicting information provided on the drywell calculations and the soil logs. Development Services obtained and reviewed the King County Department of Health On -site Design Summary. We found that the fine sand type 4 is the correct soil type. 3. In addition the summary indicated that the depth to groundwater or a restrictive layer is 24 inches. For a full infiltration design such as the current proposal there must be a minimum separation of 3 feet between the bottom of the drywell and the high ground water level. Based upon the information obtained above a drywell design is not a storm water suited for the existing site. Please contact your site civil engineer to request an alternative design that meets the 2016 KCSWDM. Respectfully, Cole Elliott, P.E. Development Services Manager cc: Andrew Norton, Plans Examiner Project File Day File \\CFWFILE I\.App1 ications\CSDC\PROD\docs\save\ I51050_78820_28145337.doc PUBLIC WORK, Drywell sizing per King County Surface Water Design Manual SWDM ,appendix C When located in coarse sands and cobbles, drywells must contain a volume of gravel equal to or greater than 60 cubic feet per 1,000 square feet of impervious surface served. When located in medium sands, drywells must contain at least 90 cubic feet of gravel per 1,000 square feet of impervious surface served. Impervious surfaces calculations Dryway: 20ft x 21.5ft = 430sgft Roof: 35ft x 48ft = 1680sgft Patio: 1 Oft x 24ft = 240sgft Total impervious surfaces: 2350sgft Gravel Required 2350sgft of impervious surfaces: 2350sgft / 1000sgft = 2.35 Coarse sands and cobbles: 60ft3x2.3 5= 141 ft3 Medium sands: 90ft3x2.35=211.50ft3 Proposed Drywell Total Proposed Volume of gravel in the drywell Diameter: 14ft; Height: 3ft V=rrr2h=3.1416*49ft2*3ft=461 ft3 The proposed drywell contains a volume of gravel (461ft3) that is double the amount of gravel —J& needed to support the proposed impervious surfaces. Go M kE5TRJCrT' ✓6 L.AyEP IS may- tjct►65 tst Ties Y'CZw IM G • z • . 't moo, L- 5VY0.w N o N boES N tT �� ��LL in►F��� 2ai�orJ (C-.i•3� r�A� RESUBMITTED FEB 25 2U19 6e 3 - FaeT r--?wffl v vJ j3 o -ITO M OF AMU" D D.DPpmwr AREA OF DISTURBANCE 1,623 BUILDING 550 DRIVEWAY, WALK 218 COV'D PATIO, 60 FRONT PORCH 2,451 TOTAL IMPERVIOUS SURFACE: 19,240 S.F. TOTAL Lot Area 1,623 BUILDING 550 DRIVEWAY, WALK 218 COV'D PATIO, 60 FRONT PORCH 2,451 TOTAL 12.74% IMPERVIOUS COVERAGE IMPERVIOUS SURFACE CALCULATIONS INCLUDE BUT NOT LIMITED TO, THE STRUCTURE ROOF AREA, DRIVEWAYS, WALKWAYS, PATIOS ETC.) LOT COVERAGE 19,240 S.F. TOTAL LOT AREA 1,623 BUILDING W/ O.H., CANT'S 218 PATIO, 60 FRONT PORH 1,901 TOTAL 9.88% COVERAGE BY STRUCTURES PRESENT USE: VACANT LOT Parcel Number: 1840800005 Taxpayer: STIHARIIVAN Legal Description: CRESTVIEW SHORECLUB ADD PLat Block: 1 Plat Lot: 1 2"X2" BY 14 Ga. WIRE OR EQUIVALENT, IF STANDARD STRENGTH FABRIC USED POST SPACING MAY BE -cli INCREASED TO V IF WIRE BACKING IS USED NOTE: FILTER FABRIC FENCES SHALL BE INSTALLED ALONG CONTOURS WHENEVER POSSIBLE Opq >oo MAN, 15 12" MIN. THICKNESS NOTES: • PER KING COUNTY ROAD DESIGN AND CONSTRUCTION STANDARDS (KCRDCS), DRIVEWAYS SHALL BE PAVED TO EDGE OF R-O-W PRIOR TO INSTALLATION OF THE CONSTRUCTION ENTRANCE TO AVOID DAMAGING OF THE ROADWAY. • IT IS RECOMMENDED THAT THE ENTRANCE BE CROWNED SO THAT RUNOFF DRAINS OFF THE PAD. Mnimum Tree Density Requirements for Vacant or Redeveloping Sites (Table 19.120.130-1) �......._ E.... Land Use Designation Required Tree Unit Density' ' _�.._..._.. BC, BN, CE, OP, PO 20 tree units/acre ........... ...................................................... i SF Residential zones 25 tree units/acre M..... ....... RM 1800, RM 2400, RM 3600 130 tree units/acre ....... ......... ...... ...... ............ ........... .. ..... .. ............... E I The following table specifies the tree unit crefts established for retained (existing) trees and planting of t Tree Unit Credits (Table 19.120.130-2) Existing Tree Category Tree Unit Credit Existing Tree 1? to 6? d.b.h. 1.0 tree units per tree Existing Tree >6? to 12? d.b.h. 1.5 tree units per tree Existing Tree >12? to 18? d.b.h. 2.0 tree units per tree Existing Tree >18? to 24? d.b.h. 2.5 tree units per tree Existing Tree > 24? d.b.h. 3.0 tree units per tree Replacement Tree Category Replacement Tree, Small Canopy Species (Mature canopy area < 450 SF) .50 tree units per tree planted Replacement Tree, Medium Canopy Species (Mature canopy area 450 to 1,250 1.0 tree units per tree planted Replacement Tree, Large Canopy Species (Mature canopy area > 1,250 SF) 11.5 tree units per tree planted *Refer to City of Federal Way Bulletin #068 for a listing of recommended tree species. ! ...._.............. .........._......._................._..W...,._. 30 CONSTR. ENRANCE ROW ACCESS (ASPHALT) E 0 21.50' 120 11 35.00' 10.00' 83.50' SINGLE COMPARTMENT 1000 gallon trash tank Salcor G-3 uv light 116 114 11 Tank soil log 110 108 106 104 102 ��w'���w �—w w��ww��ww—�ww�wwwsw w—www�w—wwww.w ww�w�ww�w w ww�ww�ww�w�w��w w ww�w .7 ww�ww��w S 9D 14' 30' E 50.00� 1750 ga pump tank PRV V Ive ' —x __----- F60 x k Geoflow Automatic �x �x H�a.�w rks 0 0 0 0 ' NVERT EL VATION 10 I ' 35' RETUR LINE I ds dslea' ntrol panel - ' r 69 ' 1" schdule 1 A 115 light I / 40 vc supply I line CO / \ / SL-5 OPOS 4 R M OUSE 116 OR MAIN FLR. 117.5' tAR. SLAB EL. 116.5' 11 w U ds M� 18' min /0 cp W 102 rdwood SL- /I\ - CP- C L113.8J ds v) - , N ' 'X 1 -X _ X —x —x -X -v N ' 0 Z) / SILT FENCE 85 1 1 - 1 I ' CO DRAINAGE FACILITY 1 2 tiq \�F s� SCALE 1 if = 20' TREE RETENTION CALC'S: UNITS REQUIRED— 25/ACRE X .44 = 11 UNITS PROVIDED— 16 AVG BUILDING ELEV. POINT ELEV A 115 B 112.5 C 113.8 115.8 115.9 F 115.8 G 116 H 117 TOTAL ............................................. TOTAL POINTS AVG GRADE EL. 921.8 /1 8 115.23 X - -X �* M N 0 tunil 0 N/X Zo )co Q 0 S L-4 I N 10 I � 104 S L- / / \ -----------------------.----- - 1.J 108 106 N 89D 14 3011 W 130.53 ect to house and driveway drainage lines „ IL MEM. �q. �fl�T�ai� �o, �;�� f � ■ C �I;� I FF 112 • SOIL LOG O AIR VENT TANK SOIL LOG ROOTS TO 27 INCHES SL-1 SMALL ROOTS TO 9 INCHES 9-30 FINE SAND TYPE 4 SL-2 0-511 TOP SOIL WITH ROTTED WOOD 5'-30" FINE SAND LIGHT BRN TYPE 4 SL-3 0-8 TOPSOIL 8-30 LT BRN FINE SAND TYPE 4 SL-4 0-24 INCHES FIND SAND TYPE 4 SL-5 0-5" TOPSOIL 5"-26" FINE LT BRN SAND TYPE 4 713 FEET OF PRESSURE COMPENSATING GEOLINE APPROXIMATELY 31023 48TH AVE SW FEDERAL WAY RECEIVE[— APR 10 201 CITY OF FEDERAL WRI COMMUNITY DEVELOPMENT URBAN DESIGN GROUP hereby reserves it's common law copyright and other property rights in these plans, ideas and designs. These ideas, designs and plans are not to be reproduced, changed or copied in any form or manner whatsoever, nor are they to be assigned to any third party, without first obtaining the express written permission from URBAN DESIGN GROUP. Written dimensions on these shall have precedence over scale dimensions. Contractors shall verify and be responsible for all dimensions and conditions of the job and URBAN DESIGN GROUP must be notified in writting of any variation from the dimensions, conditions and specifications construction shown by these drawings. All shall be in accordance with the standard building code. (SBCCI) an state and local codes. COPYRIGHT © 2010 URBAN DESIGN, INC. 0 ° U (/ U Q ° Cn L0 (D O O O O 00 0 00 C) 0 U W I- J 7 Q U 0 U 0 I --+-J 0 Q 0. J a - C IL 0 to 0 00 0) Z W rn _toZO N Z -0 W o Q .n � o c w E H Z Q Z o m LO uj 0 a00 W00 o _z a - DRAWN BY: AVA DATE ISSUED: 05/10/15 MODIFIED BY: AVA ENGINEER: GEORCR REVISION Q REVISION Project No.: 14174 SHEET IOF I 0 C W r D 0 ,0 m M 70 C/) ��z r zm o>C, o CO Crl a o 3 -n T