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SWP272913(1)
ERRICO SHORT PLAT Technical Information Report May 17, 2001 ' Owner/Developer: Joe Pruss ■ Basic Ventures Inc. ■ 21305 NE 6th Place Redmond, WA 98074 Prepared by: Robert Stewart ' ham ° Reviewed by: ' Jennifer A. Steig, P.E. Pp6 PETERSON s rs� � ' J i'I�Q ONSULTING OVAL 1 EXPIRES 09/09/02 4030 LAKE WASH INGTON BLVD,NE,SUITE 200 KIRKLAND,WASHINGTON 98033 PCE Job No. BAVE-0001 TABLE OF CONTENTS I. PROJECT OVERVIEW 1 H. CONDITIONS AND REQUIREMENTS SUMMARY 4 TASK 1: STUD YARE,4 DEFINITION&-AL4PS 8 TASK 2: RESO URCE REHEW 8 TASK 3: FIELD INSPECTION 12 TASK 4: DRAINAGE SYSTEM DESCRIPTIONAND PROBLF�1 SCREENING 13 ' IV. FLOW CONTROL AND WATER QUALITY ANALYSIS AND DESIGN 14 Existing Site Hydrology 14 Developed Site Hydrology 15 Storage Facility 17 ' IV. CONVEYANCE SYSTEMS ANALYSIS AND DESIGN 18 VI. SPECIAL REPORTS AND STUDIES 18 VII. OTHER PERMITS 18 VIII. ESC ANALYSIS AND DESIGN 18 IX. BOND QUANTITIES,FACILITY SUMMARIES AND DECLARATION OF COVENANT 19 XI. OPERATIONS AND MAINTENANCE MANUAL 19 Peterson Consulting Engineers Page i ' FIGURES Figure 1: Vicinity Map 3 Figure 2: Site Map 4 Figure 3: Basin Map 9 Figure 4: SCS Soils Map 11 Figure 5: Existing Conditions Map 17 ' Figure 6: Developed Conditions Map 18 APPENDIX A Water Works Output (Developed and Existing Flow Rates) 2 year, 10 year, and 100 year isopluvials SCS western Washington curve numbers Hydrologic soil group table for King County ' Riser Inflow Curve iAPPENDIX B King County Level One Tables and Maps APPENDIX C ' King County Drainage Basin Map King County Community Planning Areas Sensitive Area Folio Maps (Landslide, Seismic, Erosion, Coalmine, Streams and 100-Year ' Floodplains and Wetlands) APPENDIX D Geotechnical Report APPENDIX E Maintenance Guidelines for Storm/Conveyance System Peterson Consulting Engineers Page ii Technical InforniatiOn Report for Errico Short Plat Alay 17, 2001 i I. PROJECT OVERVIEW Project: Errico Short Plat PCE Job Number: BAVE - 0001 Site Area: The site consists of 26,572 Square feet—0.61 Acres. Site Location: The site is located within the City of Renton on the south side of NE 241h Street, and east of Aberdeen Avenue, (see Figure 1: Vicinity Map). More specifically, the site is located within SE '/4 of Section 5, Township 23 North, Range 5 East, W.M. Existing Adjacent Development: Existing development adjacent to the site includes the following: North—NE 24th Street East— Single Family Residential South— Single Family Residence ' West— Single Family Residence Pre-developed Site Conditions: The existing site runoff patterns are generally from east to west on the entire site. The slopes range from 0 - 6%, mostly flat through out the site. An existing single- family residence is located on the northern portion of the site. The ground cover consists of mostly poorly maintained lawn (acting as a pasture / meadow) on the remaining portions of the site. Peterson Consulting Engineers Page 1 a Technical Information Report for Errico Short Plat Hav 17, 2001 Post-developed Site Conditions: The proposal is to construct 3 lots with associated roads and utilities. (See Figure 2: Site Map). Runoff patterns from the developed site will be similar to the existing conditions. The runoff from the proposed roads will be conveyed via tightline system on the west side of the property, then north to the to the NE 24`h 1 Street storm drainage system. The runoff from the roof drains will also be conveyed using the NE 241h Street storm drainage system. See Section IV for a detailed discussion and calculations. Peterson Consulting Engineers Page 2 MA Y CREEK PARK NE 28th ST NE 28th ST KENNYDALE n I LINOS PARK NE 24th ST o COULON Z BEACH NE 20th ST SITE zr� Z � � Z ' VICINITY MAP ERRICO SHORT PLAT SEC. 5, TWP 23 N., ROE. 5 E., W.M. z 4030 Lake Washington D WN. B Y.• DA TE: JOB NO. \ ETERSON Blvd. N.E., Suite 200 BMD 5/17/01 BAVE-0001 CONSULTING Kirkland, WA 98033 :7 o Tel (425) 827-5874 CHKD. BY: SCALE: FIGURE: �o Fax(425) 822-7216 RS N/A 1 �n SEC. 5, TWP.23 N., RGE.5 E, W.M. ts m 82-. N. E_ 24'th S T 1323.06 a4444444444 N89 07'09"E _ 26' — ti 160. 55 FOUND MON " FOUND MON IN CASE »l — — —— — = IN CASE 30' 122.57 � o C _ 0 40' Uj I SCALE.- 1" = 40' - - i z I' , 3 26' INGRESS, EGRESS AND � UTILITY EASEMENT , i W J r^ W �NCL 11 , - W Z Q o o � 0 IC _ N W W N '�� OLLJ W ! Q)� - � Z o , W Z z o Y LL •a N89°7 3 32 E 122.55 STAMP NOT VALID UNLESS SIGNED AND DATED ETERSON NE 20th ST. 'CONSULTING NE 20 th S T. 4030 lake Nasbinglon o — FOUND MON Blvd, N.E., Suite 200 Kirkland, WA 98033 w FOUND MON _ - 1 - _ - - _ -- IN CASE Tel (425)827-5874 m IN CASE -- \ Fax (425)822-7218 L _ J Jos NUMBER BAVE--0001 n Q: - FIGURE h 4 Technical Information Report for Errico Short Plat ATav 17, 2001 II. CONDITIONS AND REQUIREMENTS SUMMARY CORE REQUIREMENTS: Core Requirement # 1: Discharge at the Natural Location The proposed conveyance system will be release at the natural discharge point for the project. Core Requirement # 2: Off-Site Analysis See Section III of this report. Core requirement # 3: Runoff Control See Section IV of this report for detailed discussion and calculations regarding detention. It was found after competing the calculations in section IV, that a detention system is not necessary per the exemption in the 1990 KCSWDM 1.2.3-5. See Section IV. ' Core Requirement # 4: Conveyance System The proposed conveyance system will collect and contain the stormwater from the site. Core Requirement # 5: Erosion/ Sediment Control Plan In accordance with the City of Renton Standards, a temporary erosion control plan will be designed and provided at the time of preparation of the construction documents. Core Requirement # 6: Maintenance and Operation See Section XI of this report. Core Requirement # 7: Bonds and Liability ' A bond quantities worksheet will be completed after first review. The project owner will provide bonding as required by the city of Renton. Peterson Consulting Engineers Page 5 Technical Information Report for Errico Short Plat Mav 17, 2001 SPECIAL REQUIREMENTS: Special Requirement # 1: Critical Drainage Areas The project is not designated in a critical drainage area or in an area included in an adopted master drainage plan, lake management plan or shared facility drainage plan. Special Requirement#2: Compliance with an Existing Master Drainage Plan The project is not designated in a master drainage plan, therefore no special requirement is needed. Special Requirement # 3: Conditions Requiring a Master Drainage Plan The project is not designated in a master drainage plan; therefore no special conditions are required. Special Requirement#4: Adopted Basin or Community Plan The project is located in the Cedar River Basin and East Lake Washington sub-basin but is not subject to any specific requirements per the plan. Special Requirement# 5: Special Water Quality Controls ' Water quality will does not need to be provided according to the 1990 KCSWDM (sec 1.3.5 Special Requirement #5 — Special Water Quality Controls). Water quality only needs to be provided if more than 1 acre of impervious surface is being added, and our site is only adding approximately 0.17 acres of new impervious. Special Requirement # 6: Coalescing Plate Oil/Water Separators The proposed project is not subject to this requirement. Special Requirement # 7: Closed Depressions The proposed project does not contain any closed depressions. Peterson Consulting Engineers Page 6 Technical Information Report for Errico Short Plat May 17, 2001 Special Requirement # 8: Use of Lakes, Wetlands or Closed Depressions for Peak Runoff Control The proposed project is not subject to this requirement. Special Requirement# 9: Delineation of 100-Year Floodplain The proposed does not lie with in a 100-year flood plain, therefore the project is not subject to this requirement. Special Requirement # 10: Flood Protection Facilities for Type 1 and 2 Streams The proposed project is not subject to this requirement. Special Requirement # 11: Geotechnical Analysis and Report See Appendix D for the geotechnical report. Special Requirement # 12: Soils Analysis and Report The proposed project is not subject to this requirement. Peterson Consulting Engineers Page 7 Technical Information Report for Errico Short Plat Mav 17, 2001 III. OFF-SITE ANALYSIS TASK 1: STUDY AREA DEFINITION& MAPS The 0.61-acre site is located on the south side of NE 24`h St, and east of Aberdeen AVE NE, in ' the City of Renton, Washington. More generally, the site is located in the SE 1/4 and NE 1/4 of Section 5, Township 23 North, Range 5 East W.M., in King County, Washington (see Figure 1: Vicinity Map). The site is in the Cedar River Drainage Basin and East Lake Washington Sub-basin as defined in the King County Basin Reconnaissance Program Summary Volume I (see King County Drainage Basins Map in Appendix "C"). UPSTREAM DRAINAGE ANALYSIS There is approximately .28 acres of upstream area tributary to the site (see Figure 3: Basin Map). This contributing area is coming from the lots located to the east and southeast of the site. TASK 2: RESOURCE REVIEW Support documentation for the following items may be found in the Appendix. Community Plan IThe site is located in the Newcastle Community Planning Area (see Community Planning map in Appendix"C"). Adopted Basin Plan /Basin Reconnaissance Summary Report The site is located in the Cedar River Basin and East Lake Washington Sub-basin. No basin reconnaissance report could be found for this basin. Critical Drainage Area The site is not located in any of the Critical Drainage Areas as identified in the 1998 King County Surface Water Design Manual. Peterson Consulting Engineers Page 8 I fit! 0 QQ a _ �11 N +i p o I � N , fir/ -- -'I � ,i--- ' w Y I N , i I I 195 713 96-1 1 e VPSYISA14 COAT%24Vt J4 AMh J � ' l30 , I 8 I6 = 23 2 �''� 35 25 R --- 12 ^ W l:�sz S3 11) z8_—_ 50 2 ` 34 26 -MAN -- Si'�, W �, W Z a 33 27 � l30 Q � Q 11.03 lagse / ^ �L! 8 LAJ3 Lu Ex9.04 75 Q M W °► � 5 � C}V - cQc `` �' 78.Z9 68.58 �� ?IB4 69.02 qu \v ---- -- N.E. 30 23RD > ST b 47 40 =; 2 o J I� ' {0 i I 12 13 I 14 'v- ,�66, _ 39.35 105.107 63.08 7 rt c o �w c_mac I /09 26 710.. BASIN MAP ERRICO SHORT PLAT SEC. 5, T WP 23 N., RGE. 5 E., W.M. D WN. BY. DATE: JOB NO. m� 4030 Lake Washington N ETERSON Blvd. N.E., Suite 200 BMO 5/17/01 BA VE-0001 CONSULTING Kirkland, WA 98033 Tel (425) 827-5874 CHKD. BY.• SCALE: FIGURE. o wo Fax(425) 822-72 16 RS N/A 3 F-s Technical Information Report for Errico Short Plat May 17, 2001 Sensitive Area Folio The King County Sensitive Areas maps dated 1990, revealed that the site was not located in hazard areas, such as, landslide, coal mines, erosion and seismic. The site does not contain any classified wetlands or streams (see Appendix"C" for maps). SCS Soil Survey The soils on the site, per the SCS Soils mapping, are LnC — Indianola Finny Sand Loam, (see Figure 4: SCS Soils Map). Wetlands Inventory There are no classified wetlands on-site. 1 I 1 1 Peterson Consulting Engineers Page 10 °,� +7 Agri• to V. �• �I ' II �k SYMBOL NAME rk vl. ",,!; G I.ie,w.,� ,v• I r � ..,, i � r' l� >��. (•1 � � �. �,. A;,t l.I.l.• xl. ..I: r- I I., � I( I ..y��M��. ,Y� ? CL ,p.. _ ,rl JR•' /u r-,�,,., AI, ..1 , , rt•:,. ., ..L.,......• Evf'`1 B '}- Be(. I'mouzite ovelly •:and L.,•n, /.�o IS nt r.• (''./' HeD Iieausitr gravelly Bondy loom I', , tU pr ,•nt I qr- •• _\ Ber Baousiie gravelly sandy L..,,., •1C,,: I), .,, I�IK••. �`\• d>- ��- \i<ly - ,x Bit Bellingham silt loam `: �� '`•'•:,. •`s�` �� Br Briseot silt loam \\ r e y B. Buckley silt loam Cb j� ram' 'R1�•�- Coastal Beaches � -� f nC• E. Earlmont silt loam Ed Edgewick fine sandy loam 1 r •'' Kt y / �+ _ Ev3 Everett gravelly sandy loam O to S percent sl.,pes '� ,• `d,, .,••���� r k. EvC Everett gravelly sandy loan to 15 percent slopes EvD Everett gravelly sandy Imm 1°,r:30 percent;lopes + .•'.. 'I I Ew!= Everett-A lderv:o,:!y a 11, J ._n s,6 t„ ir•Pc•�.em sloe .-I - v� InA Indionolo loamy fine sand, ,,-to ,rr.e•-r slop— Inc Indianola loamy fine sand, 4 to. 1 percent slopes _ • c --- Ar-r ' InU Indianola loamy fine Bond, IS,�to 3C percent.lopes wy t � + �lne `• '� "� -.k .yak Ev6 "4 ✓ rkF�• r •k.. -�. +. x•('r- �.��" PIT �I � . ~��rn) ` •; ^� � `� Rv� ems. �' x '' i t � l�, 3 yr7` tf. i �VI I�,a �'� Y.,� .' L. .�ryN a AkF V�` Y' .rr h � ii T•�. 'i`t.:�r�•t 1.r°r. ` `., f ' ''• — g , =vim __I '` ,• \�., _� �I I •iI•.��,��9 Ur I ,7'lr'�ii� t t � � }ti/,a 1.rAir j 3. - a+i .• , ,,'Slit -'adG fly SCS SOIL SURVEY MAP ERRICO SHORT PLAT SEC. 5, TWP 23 N., RGE. 5 E., W.M. m� 4030 Lake Washington D WN. BY. DATE: JOB NO. x N ET E RSO N Blvd. N.E., Suite 200 BMo 5/-7/01 BA VE—0001 W CONSULTING Kirkland, WA 98033 z o a Tel (425)827-5874 CHKD. B Y. SCALE: FIGURE: MU w o Fax(425) 822-7216 RS N/A 4 ��a Technical Information Report for Errico Short Plat May 17, 2001 TASK 3: FIELD INSPECTION A site visit was made on January 23, 2001, during a clear and sunny day. The site contains one single-family residence and two sheds, with grass lawn surrounding the home and sheds. A gravel driveway serves as access to the buildings from 24th Street. The topography of the site slopes to the west, (see Figure 2: Site Map). No visible downstream drainage problems were observed at the time of the field observation. i I Peterson Consulting Engineers Page 12 Technical Information Report for Errico Short Plat May 17, 2001 TASK 4: DRAINAGE SYSTEM DESCRIPTION AND PROBLEM SCREENING Please reference KC Level 1 Tables and Downstream map in Appendix"A". DRAINAGE SYSTEM DESCRIPTION Please reference the drainage system table and location map found in Appendix "A". Drainage from Basin "A" sheet flows west to the edge of the property. Where it enters a catch basin containing a 6-inch pipe. The catch basin appears to drain to the west through a 6-inch pipe under neighboring lots to the east side of Aberdeen Avenue N.E. Unable to find the end of the pipe, it is assumed it connects to the storm drainage system on Aberdeen Avenue N.E. Flow then enters Aberdeen Ave N.E. drainage system where new storm and sewer construction is in progress (point B). The new construction will divert all the flow to the north starting from the corner of 16th Street and Aberdeen. Flow will proceed to the north on Aberdeen until reaching 24th Street. Once at 24th Street, flow will then turn east for approximately 250 feet (point Q. Flow is then diverted northerly under the Kennydale Lions Park(point D) and continues in that drainage system until discharging into May Creek. No visible downstream drainage problems were observed at the time of the field investigation. Peterson Consulting Engineers Page 13 i 1 Technical Information Report for Errico Short Plat May 17, 2001 IV. FLOW CONTROL AND WATER QUALITY ANALYSIS AND DESIGN The calculations are based on the 1990 King County Surface Water Design Manual (KCSWDM) requirements. The flow rates are based on the SBUH Methodology for level pool routing using the City of Renton's design standards. Precipitation 2-Year—2.0 inches 10-Year—2.9 inches 100-Year— 3.9 inches *See Appendix B or 2, 10, and 100-year isopluvials DETENTION CALCULATIONS Existing Site Hydrology The existing site runoff patterns are generally from east to west on the entire site. The slopes range from 0 - 6%, mostly flat through out the site. An existing single-family residence is located on the northern portion of the site. The ground cover consists of maintained lawn on the remaining portions of the site (see Figure 5: Existing Conditions Map). The curve numbers used for the detention calculations are based on Hydrologic Group A soils (see Table 3.5.2B in Appendix A). Total Area= 0.90 Ac (includes offsite runoff onto site) Pervious Area=Lawn - 0.79 Ac @ CN= 65.0 Impervious Area=Residence and driveway - 0.11 Ac @ CN= 98.0 Time of Concentration= 24.48 min Reach= 240.0' sheet flow @ 2%, `ns' = 0.15 r Peterson Consulting Engineers Page 14 Technical Information Report for Errico Short Plat May 17, 2001 ' Flow Rates Using the existing hydrographs, the allowable release rates for the site were determined in accordance with the 1990 KCSWDM standards. The allowable release rates are as follows. 2-year Flow Rate= 0.04 cfs 10-year Flow Rate = 0.07 cfs 100-year Flow Rate = 0.15 cfs Developed Site Hydrolosy The proposal is to construct 3 lots with associated roads and utilities. (See Figure 2: Site Map). Runoff patterns from the developed site will be similar to the existing conditions. The runoff from the proposed roads will be conveyed via tight line system on the west side of the property, then north to the to the NE 24"' Street storm drainage system. The runoff from the roof drains will also be conveyed using the NE 24th Street storm drainage system (see Figure 6: Developed Conditions Map). The total area in the developed conditions needed to be detained is 0.90 acres. The site area was divided into pervious and impervious areas. The impervious area was modeled using an SCS curve number of 98 (concrete, asphalt, roofs). The pervious area was modeled using an SCS curve number of 68 (grass, landscaping). Total Area= 0.90 Ac (includes offsite runoff onto site) Pervious Area=Lawn— 0.63 Ac @ CN = 68.0 Impervious Area=Residence and driveway—0.27 Ac @ CN = 98.0 Time of Concentration (pervious and impervious) = 6.33 min(minimum allowed) Reach= 240.0' sheet flow @ 2%, `ns' = 0.15 Flow Rates Peterson Consulting Engineers Page 15 Technical Information Report for Errieo Short Plat May 17, 2001 Using the existing hydrographs, the allowable release rates for the site were determined in accordance with the 1990 KCSWDM standards. The allowable release rates are as follows. 2-year Flow Rate= 0.11 cfs 10-year Flow Rate= 0.19 cfs 100-year Flow Rate = 0.33 cfs EXEMPTIONS DETENTION Detention does not need to be provided according to the 1990 KCSWDM (sec 1.2.3 Core Requirement 93 —Runoff Control). If the difference between the flow rates for the 100 year existing and 100 year developed are less 0.5 cfs then detention does not need to be provided. The difference between the flow rates for our site is 0.18 cfs (developed rate— existing rate = 0.33 — 0 15 = 0 18 cfs). Therefore no detention needs to be provided. c ) WATER QUALITY Water quality will does not need to be provided according to the 1990 KCSWDM (sec 1.3.5 Special Requirement#5 — Special Water Quality Controls). Water quality only needs to be provided if more than 1 acre of impervious surface is being added, and our site is only adding approximately 0.17 acres of new impervious. Figure 6: Existing Conditions Map Peterson Consulting Engineers Page 16 ' SEC.5, TWP.23 N.,RGE 5 E., W.M. m 1 - - - - ,. z62 ^� J :k -------------- N•E. 24 th $/ 1323.06 3 +i ti FOUND MON INCASE- 160.05 _s.._ ._.__ ----•._ -s _ FOUND MON IN CASEhijo-ij! -- _ m C�3f o Q'i G tis r I Y , 0 40' _ . I I 3 I SCALE: 7" = 40 l I it Q (;^Ii ti/ , A 1 O ui - cr- W �`, 13 u, O g V W 15'UnL EASEMENT g g REC.NO.8908710851 iI Q m� w N Q ` ." N ;.r IA W � � — � W y � � z Toj ` 2 - U J,i a i 122.55 '� N8973'32 E / ro'unuir / !' UNLESSI NEDANDlDATED EASEMEN i 20'UROTY / EASEMENT EASEMENT - _ C P ETERSON 0NSULTING 1 = NE 20th ST. jf i s I FOUND MOY 4030 Lake Washington NE 20th ST. � � h, W IN CASE Blvd.Kirk Nnd, VAto 20 o 74 FOUND MON Fax (42) 822- 33 Tel (425) 7216 IN CASE ........ .... .. .... i JOB NUMBER BA V ^'/c 000I U FIGURE C aJ I ,nW SEC.5, TWP.23 N.,RGE. 5 E., W.M. m N a `'l c / I O ' NATERLMAW Exisnvc WATER MAIN - 11�111 �1 SAWCY/r LINE 12+00 I32JOS DD � -- rN.E. 24th $T 8+04.84 a' N89'07'09'1- 9+00 1 S 160.05 aI I _ 1 NOU gD Al n4 SE FOUND MOM! _• -._._ -/ ._`CB 7 ' IN CASE I "� C@ 2 TYPE 11 48• I I �./ I ...W SOLID LOCKING'LID _W SOLID LOCKING L10 /-Y 10+33 89_7710 RT I _- - C ,____._________ CAB=�� �+_-�- - AUn -�` I TOP 80.00 ,�,.. c l\..,�(y �i=- £X WADER O _ _ _ ' TOE 27B.00 I r METER 6 \ LIGHT POLE TO BE c, �" Y 4 J/4' WATER METERS FOR-� (2)?41DEC \ t .RELOCATED BY OTHERS 5Wy�3u 1 i i I � d yCi o�W @!,"� 1 Z9D PAGE 81062 PER SP _.--_,1 __--_--_-_I �., Y ai CQi N�i 3f o TOP 79.00 I 4 F iVII �� TOE 1 6.00 1 - 0 40 I (2)6 4C O ! I I 278 i EXISTING TREE TO 1 ffY SE RETAINED Q ' r I I I,77. O C9 3 TYPE 1/-72 SCALE' 1 _ 40 27s. w SOLID LOCKING LID I 1 ! 21P'" ROW TOP 276.00 /27 [PA PROPOSED W I 1 PROPOSED RNISH GRADE(TYP.) 6 2 A �1 —_ , Oil � AIk SHEEr6-----�- I—r'J---- 2I1 26'INGRESS/EGRESS AND L_ __- �—CONNECT E ANC Q *NO �'� NSIDEEW h O ' W UDLIrY EASENENr 1 I NEW SEWER SEWER f0 I Z 1 I �. 6• „or � RNCE ��� TTT W• S-00200 lM1N) w O Gg aN�-S4 Q 18 (v^J ATE ---------- SIDE sEN£R•-- CIEANOUT _.r 4 TI,iL W 6.1£i 274.6 E N n�: O g (Q O �V I _ CL,EANOUT I {� I .y Q � '6`ff 2726" I I I`. 1 Z p O V I _ i 2 ( - 1 I (2)6 oEc W I W ! i IItW WADER CAP AND MARK LOCATION ( I O IN FIELD �A71D/J I .F CLEANOUT l ) I 10•DEC 'i .... .1 .... 6'1£271.5 I .._._ ROOF DRAIN-----____ SYSTEM(TYP.) 1 =---------------7 I tL p L I a M110 ✓ 1 I B•OE i M, IMPERI�IOUS m r5'u EASEMENT 1 I ( ` lT1'P) I 11� EXISTING 4,588t S.F.F. U cc S. I REG.NO.8908I F0851 I PROPOSED 71,868.k S.F. I SEVER 70 BE-~' REM01f0 RESTORE EXI TING I LANDSCAPING IN 0 I I 5 SENG1'. KIND I LOT l SHALL T I I i .. I--- -- -CONNECT HERE-- 10' I I, EASEMENT -•'' £A MEN7 ID'UITUT-Y j _.�.�.- ... �-, I .EASEMENT .._ _.... STAMP NOT VALID UNLESSSIGNEDANDDAIED 8"IE 264.61 E 270.It ' .. CONNECT S E CONNECT S EX .. SANITARY R TO SANITARY SEWER I o I �TRACTOR TO CONTRACTOR 70 <cWiiI ry 8"IE264.32 I PETERSON NE 20th S T. SMITH Y TO EX. _ NE 20 th S T. 1 sANIrARrSEWER CONSULTING o,<, I ,CONTRACTOR 70 FOUND MON FOUND WON VERIFY ,.• .-, IN CASE IN CASE ,,,, ,,,, 4030 Lake Washington 0o Blvd. N.E., Suite 200 Kirkland, WA 98033 TO (425) 82 -5874 Fax (425) 822-9218 ti o' JOB NUMBER Q BA l/E-0001 WFIGURE 6 Technical Information Report for Errico Short Plat May 17, 2001 ' V. CONVEYANCE SYSTEMS ANALYSIS AND DESIGN The discharge from the entire project site, plus expected upstream development, was estimated to be 0.15 cfs during the 100-year storm event. Haested Methods, Inc. computer software was ' utilized to determine the full flow capacity of the project's conveyance system piping at the minimum slope. The minimum pipe slope within this project is 1.0% and can convey 3.56 cfs (see ' below), the pipe can convey 20 times more than the 100-year developed storm can produce. Therefore, the on-site system has sufficient capacity. ................................................:v:v;:..••r.•:•:w:::::v:;:•:w:r:w::v++??•'F.4:+i ..::...ry.•.v:Y:ry:•r::•:r.}•:x.Yr{:;%{::::{.ii"n}}:i$i:?;;?f., •::•:::: ......n..... r..:..::r..f/...:v..}r .. +... 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Some of the Peterson Consulting Engineers Page 18 Technical Information Report for Errico Short Plat Mav 17, 2001 measures include a rock-lined construction entrance, filter fence, and standard ground cover practices for the temporary ditches will contain all the sediment runoff this small site gives off. A construction sequence will also be used to minimize the impacts of the construction to onsite ' erosion. IX. BOND QUANTITIES, FACILITY SUMMARIES AND DECLARATION ' OF COVENANT Will be submitted after the first review. XI. OPERATIONS AND MAINTENANCE MANUAL The storm drainage elements requiring maintenance attention include the type 1 and 2 catch basin, rstorm conveyance lines, and also the detention pipe. Appendix E contains general operating and maintenance guidelines for the proposed storm drainage system. r Peterson Consulting Engineers Page 19 A „ � � W ^ � ^ 4/23/01 8 : 42 : 5 am Peterson Engineering Consulting page 1 BASIN SUMMARY ' BASIN ID: ex02 NAME : Existing 2-year SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0 . 90 Acres BASEFLOWS : 0 . 00 cfs ' RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 2 . 00 inches AREA. . : 0 . 79 Acres 0 . 11 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 65 . 00 98 . 00 TC. . . . . 24 . 48 min 6 . 33 min ABSTRACTION COEFF: 0 . 20 TcReach - Sheet L: 240 . 00 ns : 0 . 1500 p2yr: 2 . 08 s : 0 . 0200 PEAK RATE: 0 . 04 cfs VOL: 0 . 03 Ac-ft TIME: 480 min BASIN ID: ex10 NAME: Existing 10-year SBUH METHODOLOGY ' TOTAL AREA. . . . . . . : 0 . 90 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 2 . 90 inches AREA. . : 0 . 79 Acres 0 . 11 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 65 . 00 98 . 00 TC . . . . : 24 . 48 min 6 .33 min ABSTRACTION COEFF: 0 .20 TcReach - Sheet L: 240 . 00 ns : 0 . 1500 p2yr: 2 . 08 s : 0 . 0200 PEAK RATE: 0 . 07 cfs VOL: 0 . 05 Ac-ft TIME : 480 min BASIN ID: ex100 NAME: Existing 100-year ' SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0 . 90 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 3 . 90 inches AREA. . : 0 . 79 Acres 0 . 11 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 65 . 00 98 . 00 TC. . . . . 24 . 48 min 6 . 33 min ABSTRACTION COEFF: 0 . 20 ' TcReach - Sheet L: 240 . 00 ns : 0 . 1500 p2yr: 2 . 08 s : 0 . 0200 PEAK RATE : 0 . 15 cfs VOL: 0 . 10 Ac-ft TIME : 480 min 4/12/01 1 :34 : 50 pm Peterson Engineering Consulting page 1 BASIN SUMMARY BASIN ID: dev02 NAME : Developed 2-year SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0 . 90 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 2 . 00 inches AREA. . : 0 . 63 Acres 0 . 27 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 68 . 00 98 . 00 TC. . . . : 6 .33 min 6 . 33 min ABSTRACTION COEFF: 0 . 20 TcReach - Sheet L: 240 . 00 ns : 0 .1500 p2yr: 2 . 08 s : 0 . 0200 ' PEAK RATE : 0 . 11 cfs VOL: 0 . 05 Ac-ft TIME: 480 min BASIN ID: dev10 NAME : Developed 10-year SBUH METHODOLOGY TOTAL AREA. . . . . . . 0 . 90 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 2 . 90 inches AREA. . : 0 .63 Acres 0 . 27 Acres ' TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 68 . 00 98 . 00 TC. . . . . 6 .33 min 6 . 33 min ABSTRACTION COEFF: 0 . 20 TcReach - Sheet L: 240 . 00 ns : 0 .1500 p2yr: 2 . 08 s : 0 . 0200 PEAK RATE: 0 . 19 cfs VOL: 0 . 09 Ac-ft TIME: 480 min ' BASIN ID: dev100 NAME: Developed 100-year SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0 . 90 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP ' PRECIPITATION. . . . : 3 . 90 inches AREA. . : 0 . 63 Acres 0 . 27 Acres TIME INTERVAL . . . . : 10 . 00 min CN. . . . : 68 . 00 98 . 00 TC. . . . : 6 . 33 min 6 . 33 min ABSTRACTION COEFF: 0 .20 TcReach - Sheet L: 240 . 00 ns : 0 . 1500 p2yr: 2 . 08 s : 0 . 0200 PEAK RATE: 0 .33 cfs VOL: 0 . 14 Ac-ft TIME : 480 min • MA _ �■r� ` �LM apt 1 • s Nor. � l r"�JOW, VA I M f VA F1 t • WAIs►wcw•� � e i ' ��ICI ��� �� �� �,`''� 1�►. � ; �, /``�� ..ems%�t��w�w�i�'1� T�. ��rtw# �-==� � �!, ► � �. 0. 0 0 0 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL (2) CN values can be area weighted when they apply to pervious areas of similar CN's (within 20 CN points). However, high CN areas should not be combined with low CN areas (unless the low CN areas are less than 15% of the subbasin). In this case, separate hydrographs should be generated and summed to form one hydrograph. FIGURE 3.5.2A HYDROLOGIC SOIL GROUP OF THE SOILS INKING COUNTY HYDROLOGIC HYDROLOGIC SOIL GROUP GROUP* SOIL GROUP GROUP* Alderwood C Orcas Peat D Arents, Alderwcod Material C Oridia D Arents, Everett Material B Ovall C Beausite C Pilchuck C Bellingham D Puget D Briscot D Puyallup B Buckley D Ragnar B Coastal Beaches Variable Renton D Earimont Silt Loam D Riverwash Variable Edgewick C Sala[ C Everett A/B 'Sammamish 0 Indianola Seattle D itsap U Shacar D Klaus C Si Silt C Mixed Alluvial Land Variable Snohomish D Neilton A Sultan C Newberg B Tukwila D Nooksack C Urban Variable Normal Sandy Loam D Woodinville 0 HYDROLOGIC SOIL GROUP CLASSIFICATIONS A. (Low runoff potential). Soils having high infiltration rates, even when thoroughly wetted, and consisting chiefly of deep, well-to-excessively drained sands or gravels. These soils have a high rate of water transmission. B. (Moderately low runoff potential). Soils having moderate infiltration rates when thoroughly wetted, and consisting chiefly of moderately fine to moderately coarse textures. These soils have a moderate rate of ' water transmission. C. (Moderately high runoff potentiai). Soils having slow infiltration rates when thoroughly wetted, and consisting chiefly of soils with a layer that impedes downward movement of water, or soils with moderately fine to fine textures. These soils have a slow rate of water transmission. D. (High runoff potential). Soils having very slow infiltration rates when thoroughly wetted and consisting chiefly of clay soils with a high swelling potential, soils with a permanent high water table, soils with a hardpan or clay layer at or near the surface, and shallow soils over nearly impervious material. These soils have a very slow rate of water transmission. • From SCS, TR-55, Second Edition, June 19W, Exhibit A-1. Revisions made from SOS, Soil Interpretation Record, Form #5, September 1988. ' � 3.5.2-2 11/92 KING COUNTY WASHINGTON SURFACE WATER DESIGN MANUAL TABLE 3.5?B SCS WESTERN WASHINGTON RUNOFF CURVE NUMBERS SCS WESTERN WASHINGTON RUNOFF CURVE NUMBERS (Published by SCS in 1982) Runoff curve numbers for selected agricultural, suburban and urban land use for Type 1A rainfall distribution, 24-hour storm duration. CURVE NUMBERS BY HYDROLOGIC SOIL GROUP LAND USE DESCRIPTION A B C D Cultivated land(1): winter condition 86 91 94 95 Mountain open areas: low growing brush and grasslands 74 82 89 92 Meadow or pasture: 78 65 89 iWood or forest land: undisturbed or older second growth 42 64 76 81 Wood or forest land: young second growth or brush 55 72 81 86 Orchard: with cover crop 81 88 92 94 ' Open spaces, lawns, parks, golf courses, cemeteries, landscaping. d good condition: grass cover on 75% Oc 1 or more of the area L 80 86 90 ' fair condition: grass cover on 50% to 75% of the area 77 85 90 92 Gravel roads and parking lots 76 85 89 91 Dirt roads and parking lots 72 82 87 89 Impervious surfaces, pavement, roofs, etc. 98 98 98 98 Open water bodies: lakes, wetlands, ponds, etc. 100 100 100 100 Single Family Residential (2) Dwelling Unit/Gross Acre % Impervious (3) 1.0 DU/GA 15 Separate curve number 1.5 DU/GA 20 shall be selected 2.0 DU/GA 25 for pervious and 2.5 DU/GA 30 impervious portion 3.0 DU/GA 34 of the site or basin 3.5 DU/GA 38 4.0 DU/GA 42 4.5 DU/GA 46 5.0 DU/GA 48 5.5 DU/GA 50 6.0 DU/GA 52 M 6.5 DU/GA 54 7.0 DU/GA 56 Planned unit developments, % impervious condominiums, apartments, must be computed commercial business and industrial areas. (1) For a more detailed description of agricultural land use curve numbers refer to National Engineering Handbook, Section 4, Hydrology, Chapter 9, August 1972. (2) Assumes roof and driveway runoff is directed into street/storm system. (3) The remaining pervious areas (lawn) are considered to be in good condition for these curve numbers. 3.5.2-3 11/92 hrl M. 2.i ;. 33. I 542 , P F2 1 2-36 \a^�j 3 s 4 n �]d � I /4 ' 2Suj 2v 0/3 T Io' l27 eo L Zlv 0 I n 2 01 LL141v 25h I f g0 - N.E- 25 rW �n 1 _g g -96 1! -1- I ------ �, " Z4H v II� W r j.. -- - 1 fle I 0 uj Y �I o 1 I N � 1 1 � I O I��N I ��•VOI p ��{ I I 1 I I N � I I I � � I I I I I I I I N I N I .aJ S.'.3 196 7/3 S57I 1 �Q 1 I 126./ I I l01.33 60 41.33. 60 I 6 ST. NZI Sy,p '29 .9J .62 60 , 7 i T52.3 /30 i 6-741 Tp 6516 35 23 2 �I 35 25 24� 1'^ �. � c - 3 I I N N N Q N 33 Lam•' ,assz Aaq s3 ^ W 2s1 � 5 2a� � I I 2 2 W R 34 26 m 23Lo 223 Q I0 � c 33 27 �71 c - L� 1766 Z /30 3 os s Q ° 22 I Q _ o Z W / �s N.E. 23RD ST. o {� li �. 9 63 i"l T" T sa ao r ���� 4 � r 5 `� 21 (� /zo / Cl) 20 225 I ' -<1 2 I( 78.29 68.58 �� Ub4 69.02 4821 ------ ------ ------ $ N.E. 30. 23RD ST �• •8� 60 131E CV74 . z 38 L9 " 69 f9.47 ¢7 E QmmN IN 135- c MCI I I ozp 09 I -� I: n e SIN 10 11 12 13 I� 14 -055 16 7 18• 17. i r I N/.4J I rl4dI /3t5 c. e, oRa,. s..rr 144.E / 1u. 6l" "5. /03.1/ l 6.31 6307 63.08 17 /o9za 11o.4 !s $ N.E. 22ND $ ST. ° 5 �� S.P.245 78 a I o 9 a"� 8 0� m I (� • �M 3 y,. �I � '!b � h y /74.46 ^ E:O r135.3J 13 s� tQ 6 (C) *4 ti 10 0� \ °��`7 N� 211 ICI �6 0 21I33 r° -T?,Q / z \ �ll0 7 I i 234 ^ 0 2 2l0 gl 1 2 z Z W = 11 6 r e II ^� ZI Adw oo I l.79 /0C24 ao I tee , t1.ra 3 l /74.4521®� 145 �951.24�� M F..B JD II iL e N.E. tiW LI- -- 4 2101 • . 21 0 I 4 2 I I 21 ST ST. _; 9 �3 I i 13 4 ^ as 35.3 ' 41-p0- -sl.za W I 13 0 /sc "i6 O i La ^ to/ze 5 I 12 S 25 I -- �+ 7 I` Q 1744s 135 -z .39 s, 1. 3 13 low 537 W T J 9� u i J 6 I I 6 t 17 4 �---- ^15.�11 Qlro 71- I I t - /74.44 y. l76/S 15 _ 2 �,, (A) I I ^ //. s o 75 I LU{J 1 10 ' 7 2 . I 14C>/�sfi. I �x * a n o o/zs LUJJ /esa 13 1 a 12 so $ 2 I o oI �1 9 0 $ 2 01 1 90 .E 60 ropy un�;l/O eJrt W 99.87-0 2J 160 1 66.15 �1 Yr� 7S.7s o 174.44 60 Q L733 37 1 13S2 r' � e 2oTH. LC368W 60 NJ /00 So- 102.54f 1 6.9 S// �t r `ltt 1-1 59.12 1,70 1� 132. 19373 / 16 IN {t M II --__ •`� -� � IOZ'S3 ^�// \{� ;11 � ®� I-NIi � . 9 _n 1 1 1 09 io2.33IIJ I i ff17 ~I _-o _ __ {-- ------ 1 --- -- L-- - -1901- OFF-SITE ANALYSIS DRAINAGE SYSTEM TABLE SURFACE WATER DESIGN MANUAL, CORE REQUIREMENT#2 Basin: Cedar River Subbasin Name: East Lake Washington Subbasin Number: "A" tnbol drama' a ( rarr<a a >:. fop Q�;y#ance f=xts#[rtg Potertti bbservatton s i Reid SY 9 .. om>orient T4 Went trorn bite P ©aemarbterrt5 inspector, resc► rce Na .e and Size Qecripti? n dEsharg reviewer;or reiiz�et ut f of rAblem see a . . f sheet tloyu,suva[e> drainage taas�n °4:::. /.m1 -1, f#.. anstrivf+ons,iJrider capactty pbndrrag trip aryrea'1#k�#f3Qnd.. p Yf ..... ,u et # +ri, ways,p©teit�ai�mpaits stream::channel,>:„„mmom� rid cauee depth t rp�pf;ser r►/ r�uertopp�ig loaduhg;habit ar©rg2r►�srn �verflavu pa. :I.:.:: 1:T`I'�I Size d..#ameter,surtace area aria,uotumQ destrtictioit,scoi,rmg hank tat� hiti MIA ifzcis[on::ctt��r sroskit� ; . A Site Sheet flow 1% 0 None None No erosion exists. B Aberdeen AVE Concentrated flow n/a 150—300 None None No erosion exists. Catch Basin and Drainage System C 24`h St NE Catch Concentrated flow n/a 300 — 550 None None No erosion exists. Basin and Drainage System D Kennydale Lions Concentrated flow n/a 550 - 1100 None None No erosion exists. Park Catch Basin and Drainage System 98-4\inBO4 w �"� � � i � � � � � � � � � � � � ! � � � Arl Kino C0nnty Dr-ainae Basin Map SN OU m1 T/E Site ;:: 5 »llll C. P U Q ET .� _ .4 .M Imo aw on mom 71 A Upper � soo 0.. V1,ft- Ilk •, f FlIm DRAT NAC I Malmo G.,d Lmill (+ Iddle `J I cm I Ilk, S. — BA i„ WN W�►:- etIL a• ;lid s a fffTTliaaal } it 77 \r, 1 I + �{+S 71 1— i 111 Ll�, It l• 1 : IOCY, .,.j am• i (fl, J� i Ott' T 1 fir' I. J I. j ..I `'i.',- � � \ ,1i E try, • �, \ I .. L t .r r , I1 • Nttbr J ��t\ I , �` � :� l�` k�� /.::'" ,/ ..t�:+, ,y .t'. / 1 a� ".ice al• — • "r �. � •� ti � I tyJ� , 1 i � I � II /�•y `tI�• 1,YYY\/// ! t •�1� ., Duwamish Landslide Hazard Areas 21 , 13 _ s f g 14� 7 -FV -1v it 4- 5r _71 Y; N. 7-� 7'� 1-T Site IT it 11 7.� "A j 'Fir, t AIN S U 4e M 1XI -Xibri 3D 17 1 441� 1 s have had additional min- Duwamish I st recn w e t map was filed , th n Department of Natural COC-d Mine Hazar d t development that � I Re- curs areas should be preceded Areas 767 d i i y to confirm or deny the tional subsurface tunnels. u "i2 L i�.1- f 1 �,f[� �:;t ( I' i � )� �{{•(��\�i�'''�•-+�h' � ' `i I. I �a I I :�- i f` j i 1., /.+.�..(CI+I '`` ..."t I i ! I N s o i T�ff//.��i' \ t, ' ,'•. �r,.-:_ 1 , j \ i y Imo: ,-,l S'l i 1t,•^_y' r r -+ �1.. t - "'i �% �>� '-I ' 1..`1 ,�~t' r � [ rr r •_( _ __ �, \,.�` --.may']{j�/`� t 1, \ a 1 c�C _ r f r 1J ¢� a - J �Yk j\�r It Y r�1 I +,{,� I:r)' M�v'r. c •r :•,1��F� __i'�" 7 ` I _ -��. \ ..,tom.. l 1 � Yj'r ��Y �•,• �� 1~ y� 1 1 y �r " - 4 j ('}} f aitER ;` �t 1 o f ,'isl k r r :L 4 \ _ �\l i i 1_ I �•I. 11 �.i i �,�J�� I ``� X. Iand landslide hazard maps for Seismic Hazard DuVVamish lan sli seismic re sus areas. landslide areas are susceptible ng earthquakes. Other seismic _{as not shown on this map are Ar eas 2iI 13Ii cnderlain by Iacustrine sediments: _i 41 eplible to liquefaction. 9 14! i 10_ 6 t1 LL �41� �4 1:t'•— •»r I'�T ! f. I I � ,`i �'- � 1 � •.•-�..`•.-1 �'_]. � l.. � � I J . � {tJ�I 1 c:: �e�1 r�_. r Imo• ��— s j s i• �" it 4 , r S" NN- Ncj �..1. _!�r" l,Y.^ •.,. i: .. ad 1: �t`'.�,, �v�'. l• .w '' ` ewr. to — \�+ - Jf Site MR 30 25 -"s ,Y-3 Yw' I� � �}*�-•- J.. • '`r v - L:e � ^ r.�, •x''t„1•� ���! Erosion Hazard Duwamish Areas 3 .16 • S:H IO _p17 1 r i r! l\r ,I I ,•� 1 1, f Il�� ' �. `% Iff_J '.1.J,•���i >� Il i,.�� iI I .. , Ell' L J / I:a Site71 i t ti l �.. r 1I ': r i\ i�.� r .. ,1+ \�, Y ' 11• rt r Ip: 1' ' `�t �1Z �..- i ,q 1 1.,,\` T. 1 kr &. 1 .! 1 �., .i I 1 ,� W1d... u �_,f s. , ` i:,\'l• l\:t �r. :cFi. _! 1,�`� � � �� '�� .�). * ' „ I:.G ' ,fit. t .; \ \�•, -it �� 1 '"� . ._� F u I t , T' _ �'77 vvy`� ndred year floodplalns extend be- Class 1 Duwamish lhc,se shown on n,aPs. 1=1oad In- Streams and 100 - -•-�-� Class 2(with salmonids) Ce Rale Maps do not always show the 11in. to hcad,vatcr5 of streams. Year Floodplains ; Class 2(perennial;salmonid a i la' use undetermined) �� !ta • • • • • Class 3 r' g 1071 100-Year Floodplalns _ _ _ Unclassified merber. 7 9 A -14 1.f.1.4 4 N, Merc(,ristand West, C#s1,rrjiek Lake A -.4 J14 -"N,\/,44shington ��� `'`�\ x.l.-y •.4@ J ` .•r.���'!',+ �i,�\ Z `y / r 1-•9f T 7'1 N, %1 7:1 te - I Ob - 4. b- �21hl Washington 1 7, 93b -4 -5' ne� j L b A IF" A7 jIbe I. rrf 25 -44 IL Duwamish crew Wetlands, except those Wetiands (tesi ., i" ,.- Wetlands, IIIc -2 7 3 Tnation'are,includc • Hand it venlon. f wetlands designated Open Water _ ME] fier, , oilthe site by a variely "1 9 14 Wetlands designated "b" We ( Basin Boundaries it je U.S. Fish and wildiiie 1�,e,vlcu 0 ul it their luca- c not been field verified. Sub-basin Boundaries T may 3Y be pans in file numbering se- 1_1 th it, Individual drainage basins. A ,� � ^ A W � � V Ziouer Zeman Assqdatq$,....Lm . Ge:,m:chnical wd Enviran-neatal Consuirang, J-919 February 13,2001 fir. To,mas Wolter Skyline Properties 66i— 120"'Avinme NNE` Suite D-204 Bellevue,Washingtol, 93005 Subjtect; Report of Servim. Soil Assessment for Infiltration Trenches Emc-o Short Plat—NE 24"Stricet Reljloll,Washington Dear Mr. 'Notter: Thii 1.0nur rcp ort, pmlsmt� the results of our gootechnical soil assessment at the proposed Ei-zicc short LA.at ci-,NE 241h Street in Renton. Washington, The puqiOse of our services wag to ' _ as,%is; in. OVIluatijigsoil tYPes relative to the design and construction of stormwater infiltration trenches. This evaivation was completed in general accordance with our proposal for 1. Servik:es�'No. P-956)dated Atnuary 23,2001. FIELD 'EM"LONXECON ' -� Thy ,iejd clx1flkration for, this study imcljded 1: .- cx(,,4va.tI-,,)jj cf foul- (4) pits in the W-1ZITe"ril FlOrtion (if Elie r-roperry (Mict A. aind southsvizst x)rtiori of Lot 2), The &pproxlmate it-, Figure)n th e he test pits were ,,, the test pi l are'S Oo wi, -, Figure I Sit ( e an " Exployab-m Plan). I ZZA ws the selected infi'l-ratior. trench locatinil The test pits ' :t<y cxeavated, b- � rullber-thd(l backhoe on Febn:klry 5. 200t. A representative of 7.7A 11C exci-ve.l.'�CIns and soil condidons. Select soil samples w1cre coketed ard , Stmg. Topsoil 1-Y 1'ca rOCAS was i Hi i:orsjsti.,�W, uf loose sand and silty san'd ith ahu! the ce 'r; die test pits. This ropsoil zone extended to depfli,; ranging irom ' S�I ZIj.:'r ti:.'� XI rve -)eta -Al art! !")wn. 1A.->oi!. to appro, 1.5 fixt. The stirs obse -d t I -A, the tops( V,&APO�;,^d zatiltr-atior. zone generally eonsisuvd of two pi-iincipal. -,oil types. Laose ti) 'ic, iUfll -,.Q t nv-,divnna sand W:rh trace m some MiIt and uace gravel - as en(;oLmtered in ' ;tEf s t Ot )! iir �� t t i P arid '1114, and as an i1itcrbedided lay' er betweenu mi,&urnst:r, :�,'ndv ..!I: IT" nit ,,,c ��md -timt exteided to dp,,ehs of'4 -and 4.5 I-et in test pits rp.,, S11L was the predimninant t oil i- pe observed in the cest tons.' Jt C` ( �:? }i, vt :i R Alt �! 4 excavat pt mmiffl_-na gi:oundwater Nible was, uot znoc sf.ep-age was obF,,,:m--d In tilst pit TP- 'n pa� ai tl, tittle of exc.-Avation. tit F. Log,� of the test pits w- attached to this repert. wd, Wwihixigrum 9803f, Z 5'!7 7*1 3 04 1-919 Emco Sliort.Plaa M 2001 Renton.Wa,-!�dngrwc: Page 2 i � Part orls i:!f tfi� two representative -,Oil types recovered ftom the test pits were returned to out laboraion- Ibr grain sizo distribution testing. The results .-)f the gr'ain,nze analyses a-re attached to this rqx)m CONCLUSIO ,6 X�%D REMINEVIENDAT IONS The rcstills oil'the test pit explorations and grain size distribution testing indicate that a la, I - layered soil homrsm w4h sand above silt is present in. the proposed infiltration. -areas on the YMW.rty. Ba3ed on the results of the grain size distribution tests, we recornmend that the upper sand zone lb,: cla;;,%iflled as WiD according to the United States Department of Agric-alturc (USDA) tcviirai n1angnIor classiffication system. The lower sandy silt should be classified m SIIJ "LOAN-1, 'I"his SILT LC AIM is anticipated to be at, or within 3 feet, of the base of the ai-A is c�ynqidered the soil type that will cont.0) tile infill-tratiG tr=chcs. r) lit recommend that the infiltration trenches be designed according to the K-ng County Surface Water Desigr Manual based on a USDA soil type of SILT LOM4. No peri-nanent groundwater t-,ihle was in the test pits to the maximum exploration depth o-l" 10-5 feet below the s-jzface. We understand that the base of the trenches will be on the order of 3 to 5 feet betevv ttic cxiA', g sp -,urnd SUrfi0e. Therefore, it is our opinion that there will be a minimum the bottom of the infiltration Ircriches and the perinvnent g7mind motor vabl�. lusy OF THM'� Hj!Pt-Xj ' �. (°, 1 i';tr4'ii -)perti -this. -evort for use. by Skyline Pri eN and other mental- r" of the rrolt::!' Teim Tbr '-wo Ct'alStrul:U011 of tht propimed sturnnvar,,r infilltration trencl'ics -at the M, -41 Strect :n Renton. IA:`shingtort, Thibs im"orma-tion can bQ utilized for th,1- Iwcv.dcd eSIC-MiRC 3,0;11 types for the desist of slonnivater infiltT-ation trrenches, bw of s shmuld iia-I b,,-- -onst.-ued las a warrenly of the subsurface TI.(.1 j I I o T ' Y� r,{?;:, pe. 6ichedule and OLV Se..MCOS 11 ot 'sc;o havi-,been executed M uno--na-I!y ac .opt ild-pnv;ices in this ii-la ui ffic time the r.--p.m. wa.s preparzd' No exoess or irnofif-d,should t*vl- under5tood, S (425)7 7 YOU 9 3 V` Mwi n9 to, n.9SO. 3-919 13.rriw Shorl Mai Fe6rean, 13,200i Pag Renton,waslyi!qW1., W, u-ist this infonnallon Meets your present needs. If you have any questions or if we ca.-'j he of flv-tivalr a&4Xance'please Call. Respectfully submitted, ZTIPER ZEINiAN ASSOCIATES, MC. re ct. rl Timothy 14. Rol erts, P.G. Project Engin-ler ' w '""`_ _ times B. Thompson, P.E. WW2 "FigvrL 1, Sile and Exploration Plan 6t Pit Lew(TP I through TP-4) ' w I '. (Ir"I't)-Size Distribution Results I'i )p-r Zenian Associates, I tic. 'A036 42 1 3 rr r�r rr rr rr �r r r rr rr rr rr rr rr rr rr rr rr rr 1 SCekLC,1N EE=T EXPLANATION 4 Etit.f it nub bct And S!#Ypr :ittmto locat-lon. gt�} i J. LOT 3 LOT 2 E i ` 4 E � z E tit � t i ( HOUSE I 4 t & TRACT A L.M iL M.DDL t':t),'hO'1 DRAYS MG.f' OV iDM BY i'i:WRSos cuNsuu Ah N,E.NDA'i t33 i Zi['YE:R'LEhfAti :lS>CtC:C. 'TES,L�iC. FRC}L'CrriO. r.4i9 ERRICO SHORT PLAT t DAI F: I-Ef.49UARY 200. REPE'1'G�(,\+�'ASf�t'NNOTO" } ?RI.KkRIM fly: Grx � I IN'i(•r..'_AND rN VIRON-YM.r_`ikN Al- flN.A WN BY. S:M'AND�?i3�i_{�ItI�TIU�{'u.,� ('i't1�2E 1 __._—_._......._.. 1 S" f-919 Test Pit I-Q9 Page I ' y Test-PiCIT-1 r _ p !�5 Me L Lk-LA-11jr-c-el-11-1 Material 0.0-0.18 LA)ose,Tnoist,dark brown, silty,tine SAM with aLrundantfine racts, to medluin dense, moist,mottled orangc-hruxr, fine SAND `Nith LTac silt. 4.0--9.0 stiff, inoist to wet, mottled orange-Im-own, Sandy SILT. Tcstpi.-.ornpleiedit 9.0 feet on 215/01. NO goundwater s cpage observed. r -- r � ,Mate.631 Descrintiew Sanilsl r _ 7).tE ,; No —cost:. n,iots,., dark brcivvn.silty, fine, F).A�Nf) abundant fine roots. S?-iff, mioist, niottled onaage-brown, fine SAND with trace Stli. S-I( 2-11' Mvhuni dense-, mcwit, mottled oratige-bruwa, file SAND xith trace. 6.0- 0.5 to wct, 11-t1 tilco, su"-A-y 51f.'L a! i0.5 i-ect on.2,,;,O.l bserved at 6 fem. Ga; f 10"Pif ar r-919 ReAkrOn, WA Test.Pit[.u.. Page 2 W Uc trF:,.�f tt MateriaLD -scri tiori am lc C).C)-0.8 Loo.w, moist, dark brown, silty. fine SAN with abandayit fine coots. .range-brown to tight bro%vn, sandy SILT. S-1 @,;4.5" "e_;;t nit compicted, at 10.0 fact On 2/51t?1. 0 oundwater seepage observed, "test Pit TP-4 Malerial UescriWi(._a NO. ^' It ti,.i•.. ......;,•`;'., !1^+3":sty ilark *?rovoi, Fnl+ SANI ',v th ti-ue sil? Sind abu ndhin:t ?ITto Tool's i'�i3xlSit}1) "[iC.Ji'L I.—±.l fl'r15 ,IT2Citit, 11Q t r3i C>ti:l .1:iC:J 4 � �ulill?t�Cw �t,j_ <�. 1!{':3... tl q :tf..1i II st;'It. Mcliat; Izglxt bI-o-,,v-n,SnarldV Sl.I,t,. 1'c:i :;it c.zirtnleed at 10.5 feet cia :;,c ;�:'.3 J iC141:xt.r s e p Ilge elbsMed w i 1 _ 1 GRAIN SIZE DISTRIBUTIONASTNI 0422 ��Z-r OF OPRENiNG IN INOFIES U.8,STANCARD SIEVE�'12:E HYDROMETER 1112, ve :Or 4 15 on 1P.0 M$ —r 7-L. z i ............ ........... 4 -4 ' ...-,,. [!i!Ii{hf` ............ L ;q. 4 ............ a I i z 3 . ......... uj .......... —7'...... 7 if LU 4........... A U� CL 30- i ....................... W 0.01 GRAIN SIZE IN MILLIMETERS silt !C!av 4k Q FINE SKAN escriphon 25+ SAND.some sit. trace gravef. 7.IPPF-R.ZEMAN ASSOCiATES, MC. i PROJECT NO: PROjECT rie*WE UAni .)F TEST;ING 2,'WO'! Flat MEiNTAL D"N-sk;OP NG i 4.ln r -T— U ' " GRAIN SIZE DISTRIBUTION ASTM D422 SIZE OF OF"55NING VN NCHES U.S.SO TANDIARD SICIVE SIZE HYDROMETSP U. W iW 2W 10G_ If . . ......... fit.:.;.. oi. H1 . 7 1 co tr 00— t t t i r 44 ...... .......... 'T i W40 ............. iM . Oct { i_ ........... 17 T L .................. 4 1.00 0.113 0.01 o.ux) GRAIN SIZE IN MILLIMETERS ............_._ . .............. i, i .0 Zm SAND F'NE GRAIN$jD ............. ....................... 20 f 74 Sandy SILT%Ni trace gravel. ZIPPER AS— PROJEC' NAME: ;:r6w shcrt Plit -Tr ":)p ES"�r;C Cv(V:-"rJ'N,'1;1ENTAL DA ................. ................... ........... �I �-+ �I w APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 5-CATCH BASINS Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is performed General Trash&Debris Trash or debris of more than 1/2 cubic foot which is No Trash or debris located (Includes Sediment) located immediately in front of the catch basin immediately in front of catch opening or is blocking capacity of the basin by basin opening. more than 10% Trash or debris(in the basin)that exceeds 1/3 the No trash or debris in the catch depth from the bottom of basin to invert the lowest basin. pipe into or out of the basin. Trash or debris in any inlet or outlet pipe blocking Inlet and outlet pipes free of more than 1/3 of its height. trash or debris. Dead animals or vegetation that could generate No dead animals or vegetation odors that could cause complaints or dangerous present within the catch basin. gases(e.g.,methane). Deposits of garbage exceeding 1 cubic foot in No condition present which volume would attract or support the breeding of insects or rodents. Structure Damage to Comer of frame extends more than 3/4 inch past Frame is even with curb. Frame and/or Top Slab curb face into the street(If applicable). Top slab has holes larger than 2 square inches or Top slab is free of holes and cracks wider than 1/4 inch(intent is to make sure cracks. all material is running into basin). Frame not sitting flush on top slab,i.e.,separation Frame is sitting flush on top ' of more than 3/4 inch of the frame from the top slab. slab. Cracks in Basin Walls/ Cracks wider than 1/2 inch and longer than 3 feet, Basin replaced or repaired to Bottom any evidence of soil particles entering catch basin design standards. through cracks,or maintenance person judges that structure is unsound. Cracks wider than 1/2 inch and longer than 1 foot No cracks more than 1/4 inch at the joint of any inlet/outlet pipe or any evidence wide at the joint of inlet/outlet _ of soil particles entering catch basin through pipe. cracks. Sediment/ Basin has settled more than 1 inch or has rotated Basin replaced or repaired to Misalignment more than 2 inches out of alignment. design standards. 1998 Surface Water Design Manual A-5 9/I/98 ' APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 5-CATCH BASINS (CONTINUED) Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is performed I. Fire Hazard Presence of chemicals such as natural gas,oil and No flammable chemicals gasoline. present. Vegetation Vegetation growing across and blocking more than No vegetation blocking opening 10%of the basin opening. to basin. Vegetation growing in inlet/outlet pipe joints that is No vegetation or root growth more than six inches tall and less than six inches present. apart. 1 Pollution Nonflammable chemicals of more than 1/2 cubic foot No pollution present other than per three feet of basin length. surface film. ' Catch Basin Cover Cover Not in Place Cover is missing or only partially in place.Any open Catch basin cover is closed catch basin requires maintenance. Locking Mechanism Mechanism cannot be opened by on maintenance Mechanism opens with proper Not Working person with proper tools.Bolts into frame have less tools. than 1/2 inch of thread. Cover Difficult to One maintenance person cannot remove lid after Cover can be removed by one Remove applying 80 lbs.of lift;intent is keep cover from maintenance person. sealing off access to maintenance. Ladder Ladder Rungs Ladder is unsafe due to missing rungs,misalignment, Ladder meets design standards Unsafe rust,cracks,or sharp edges. and allows maintenance person safe access. Metal Grates Grate with opening wider than 7/8 inch. Grate opening meets design (If Applicable) standards. Trash and Debris Trash and debris that is blocking more than 20%of Grate free of trash and debris. grate surface. Damaged or Grate missing or broken member(s)of the grate. Grate is in place and meets Missing. design standards. ' NO. 6 DEBRIS BARRIERS (E.G.,TRASH RACKS) Maintenance Defect Condition When Maintenance is Needed Results Expected When Components Maintenance is Performed. General Trash and Debris Trash or debris that is plugging more than 20%of Barrier clear to receive capacity the openings in the barrier, flow. Metal - Damaged/Missing Bars are bent out of shape more than 3 inches. Bars in place with no bends more Bars. than 3/4 inch. Bars are missing or entire barrier missing. Bars in place according to ' design. Bars are loose and rust is causing 50%deterioration Repair or replace barrier to to any part of barrier. design standards. 9/1/98 1998 Surface Water Design Manual A-6 ' APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 7- ENERGY DISSIPATERS ' Maintenance Defect Conditions When Maintenance is Needed Results Expected When Components Maintenance is Performed. External: Rock Pad Missing or Moved Only one layer of rock exists above native soil in Replace rocks to design Rock area five square feet or larger,or any exposure of standards. native soil. Dispersion Trench Pipe Plugged with Accumulated sediment that exceeds 20%of the Pipe cleaned/flushed so that it Sediment design depth. matches design. Not Discharging Visual evidence of water discharging at Trench must be redesigned or Water Properly concentrated points along trench(normal condition rebuilt to standards. is a"sheet flow"of water along trench). Intent is to prevent erosion damage. Perforations Over 1/2 of perforations in pipe are plugged with Clean or replace perforated pipe. ' Plugged. debris and sediment. Water Flows Out Maintenance person observes water flowing out Facility must be rebuilt or Top of"Distributor" during any storm less than the design storm or its redesigned to standards. 1 Catch Basin. causing or appears likely to cause damage. Receiving Area Water in receiving area is causing or has potential No danger of landslides. Over-Saturated of causing landslide problems. Internal: Manhole/Chamber Wom or Damaged Structure dissipating flow deteriorates to 1/2 or Replace structure to design Post.Baffles,Side original size or any concentrated wom spot standards. of Chamber exceeding one square foot which would make structure unsound. Other Defects See"Catch Basins"Standard No.5 See"Catch Basins"Standard No. 5 r M 1998 Surface Water Design Manual A-7 9/1/98 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 10- CONVEYANCE SYSTEMS(PIPES & DITCHES) �.1 Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Pipes Sediment&Debris Accumulated sediment that exceeds 20%of the Pipe cleaned of all sediment diameter of the pipe. and debris. Vegetation Vegetation that reduces free movement of water All vegetation removed so water through pipes. flows freely through pipes. Damaged Protective coating is damaged; rust is causing Pipe repaired or replaced. more than 50%deterioration to any part of pipe. ' Any dent that decreases the cross section area of Pipe repaired or replaced. pipe by more than 20%. Open Ditches Trash&Debris Trash and debris exceeds 1 cubic foot per 1,000 Trash and debris cleared from ' square feet of ditch and slopes. ditches. Sediment Accumulated sediment that exceeds 20%of the Ditch cleaned/flushed of all design depth. sediment and debris so that it matches design. Vegetation Vegetation that reduces free movement of water Water flows freely through through ditches. ditches. Erosion Damage to See"Ponds"Standard No. 1 See"Ponds"Standard No. 1 Slopes Rock Lining Out of Maintenance person can see native soil beneath Replace rocks to design Place or Missing(If the rock lining. standards. Applicable). Catch Basins See"Catch Basins:Standard No.5 See"Catch Basins"Standard No.5 1 Debris Barriers See"Debris Barriers"Standard No.6 See"Debris Barriers"Standard (e.g.,Trash Rack) No.6 NO. 11 -GROUNDS(LANDSCAPING) Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed General Weeds Weeds growing in more than 20%of the landscaped Weeds present in less than 5% (Nonpoisonous) area(trees and shrubs only). of the landscaped area. Safety Hazard Any presence of poison ivy or other poisonous No poisonous vegetation vegetation. present in landscaped area. Trash or Litter Paper,cans,bottles,totaling more than 1 cubic foot Area clear of litter. within a landscaped area(trees and shrubs only)of _ 1,000 square feet. Trees and Shrubs Damaged Limbs or parts of trees or shrubs that are split or Trees and shrubs with less than broken which affect more than 25%of the total 5%of total foliage with split or foliage of the tree or shrub. broken limbs. Trees or shrubs that have been blown down or Tree or shrub in place free of knocked over. injury. Trees or shrubs which are not adequately supported Tree or shrub in place and or are leaning over,causing exposure of the roots. adequately supported;remove any dead or diseased trees. 1998 Surface Water Design Manual 9/1/98 A-9 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 12-ACCESS ROADS/EASEMENTS Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed (' General Trash and Debris Trash and debris exceeds 1 cubic foot per 1,000 Roadway free of debris which square feet i.e.,trash and debris would fill up could damage tires. one standards size garbage can. Blocked Roadway Debris which could damage vehicle tires (glass Roadway free of debris which or metal). could damage tires. Any obstruction which reduces clearance above Roadway overhead clear to 14 feet road surface to less than 14 feet high. Any obstruction restricting the access to a 10 to Obstruction removed to allow at 12 foot width for a distance of more than 12 feet least a 12 foot access. or any point restricting access to less than a 10 foot width. Road Surface Settlement, Potholes, When any surface defect exceeds 6 inches in Road surface uniformly smooth Mush Spots,Ruts depth and 6 square feet in area. In general,any with no evidence of settlement, surface defect which hinders or prevents potholes,mush spots,or ruts. maintenance access. Vegetation in Road Weeds growing in the road surface that are Road surface free of weeds taller Surface more than 6 inches tall and less than 6 inches than 2 inches. tall and less than 6 inches apart within a 400- square foot area. Modular Grid Build-up of sediment mildly contaminated with Removal of sediment and disposal Pavement petroleum hydrocarbons. in keeping with Health Department recommendations for mildly contaminated soils or catch basin sediments. Shoulders and Erosion Damage Erosion within 1 foot of the roadway more than 8 Shoulder free of erosion and Ditches inches wide and 6 inches deep. matching the surrounding road. Weeds and Brush Weeds and brush exceed 18 inches in height or Weeds and brush cut to 2 inches hinder maintenance access. in height or cleared in such a way as to allow maintenance access. 9/l/98 1998 Surface Water Design Manual A-10 L A.- o l - Short Plat'(SH REQUEST FOR PROJECT# Pnum-Plat (PP# ) CAG# i I To: Technical Services Date Z� 1_U) WON Y PJ( 1.j Green# From: Plan Review/Project Manager )()l lG n n eA f1'4h Ide- - V -7-2--7 9 Project Name `��°' Q 5YW+ 0 01.1 - (Io charactc s r=) Description of Project: ffl2aA pled--. Cryr CL) .�{ Gf oy H Q I.C, G-C _ la" gran dorm �- ��� (�6 IC oC (p '` 5icrm drea'in In - n h �,d�e Wenu Culr b N n1E o1y ►^Pe r` n � Circle St o� terline: .V 10" 12" Circle One: New or Extension Circle Size of Sewerline: 8" 10" 12" Circle One: New or Extension Circle Size of Stormline: 12" 15" 18" 24" Circle One: New or Extension Address or Street Names) 'a `j I V C a q-0 !&Ir Dvlpr/Contractor/Owner/Cnslt:: charaaca mvc) Check each discipline involved in Project Ltr Drwg #of sheets per discipline Trans-Storm ❑ (Road way/Drainagc) (Off site improvcments)(indudc basin name) (include TESC sheets) ❑. Transportation (Sig Wizadon,Channdizauoa.Lighting) ❑ ❑ ❑ Wastewater ❑ ❑ — Sanieary Sewcr Main(includc basin name) ❑ Water (Mains.valves.Hydrants) O ❑ (Inelastic campositc E:Horizontal Cui Sheets) Suface Water O ❑ Lmprovements (C1P ONLY)(includc basin name) TS Use Only � W, ,?7 P ETERSON CONSULTING L4 ' 4030 Lake Washington Blvd. N.E., Suite 200, Kirkland, WA 98033