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Home My WebLink AboutMisc• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Drainage Report · MAIR SHORT PLAT 13606 156111 Ave SE Renton, WA 98116 LUA14-000708 October 81 \ 2014 Prepared for: Andrew Michael Construction, LLC POBox6l27 Bellevue, WA 98008 206 714-7161 Prepared by: Development Management Engineers, LLC 5326 SW Manning St Seattle, WA 98116 206 714-7161 cliff@sitedme.com · CITY OF P:ENTON RECEIVED OCT 0~ 2014 BUILDING DIVISION • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Table of Contents Section 1 Introduction ..._ Overview -Existing Conditions ..._ Conditions and Requirements Summary ..._ Drainage Review Type Section 2 Condition and Requirements Summary J... Core Requirement No. 1: Discharge at Natural Location , ,1.. Core Requirement No. 2: Offsite Analysis ,1.. Core Requirement No. 3: Flow Control J... Core Requirement No. 4: Conveyance System J... Core Requirement No. 5: Erosion and Sediment Contte! ,1.. Core Requirement No. 6: Maintenance and Operation ,1.. Core Requirement No. 7: Financial Guarantees and Liability ,1.. Core Requirement No. 8: Water Quality J... Special Reports and Studies ,1.. Other Permits Section 3 Off-site Analysis ,1.. Upstream ,1.. Downstream Section 4 Flow Control List of Figures 1.1 Figure 1.1.2A (Project generated) 1.2Figure 1.1.2A (City generated) 3.lHighlands Estates Drainage Plan Sheet C12 3.2Highlands Estates Drainage Profile Sheet C13 3.3Highlands Estates Wet Vault Sheet C16 3.4Highlands Estates Detention Tanks Sheet C17 · 3.5 "Local System" Drainage basin 3.~Evendell Storm Drainage Plan 3.7Saddlebrook (Div II) Sheet ClO List of Tables 1. Mair SP Area Summary Table 2. Mair SP Land Use Area Table 3. Mair SP Downstream Storm Drain System Appendix A -Drainage Area Storm System Map B -Highland Estates Design Parameters C -Photos of Evendell CB#53 and HE CB#38 no11Jubo,jnJ ·t ricrbs2 r)flOi:tif:"i.1c,') f:'r:i:~lX] ·· 1i/='iV1~VU 1 r1r:.~,,:r 111 ? .... r ~\i C, l:11 ~,,q ru,·1r----=f·'\!1,·or:o'") .. \ .... ' ...... -... ' ............ , • .,., ...... ,v., \\ •• :qyT I J.,';l'.l'.iH !:JQ6fl!G10 ·' v1nmrr1>.k'. 2)r1'Jr119·,il't'.:lf: 'Ji'i'i rioViibnoJ s: ·~oi!J~-2 rv~ ;,;,,"Jo~ ls11t·i;-;1,~ io S(,11·; · J)2iO : J. .t1V'. -;n9i •1!J1iu1 .. :J.!=t (nr<) ,~i2vtcrl\ '.:;.j;z\10 ; \ .0V1 ·tn3rns·:11.:p~·~ s·:v) _,, !m '.r10·, W('l1 :[ .Oi•'i jr,9f)1'.),1i.Ji}S>t :''l\'i) 'l,~:2\1?. :t.Ji1uv~~vr10J :i' .oL·1 ·:;J'7in~,1iuµ::;.H .._:no:-1 .~· 1 j ', I 'k -;;; ' · ·, in ·> ' n -, ,,_:; :'.~J.. .,r:.:1f.lld~~ ljflf:i r '!\('.(Y'!.J . 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The existing house and detached garage which fronts 156111 Ave SE will remain on the proposed western Lot 1, (16,545 sq ft) without further modification. The new Lot 2, (9,650 sq ft) will front onto SE 2nd PL. The development will include a dedication of 663 sq. ft. to the City of Renton for 156111 Ave SE right of way widening . It is proposed to retain the recently constructed frontage improvements along SE 2"d PL. New frontage improvements consisting of curb and gutter, an 8-foot planter strip and 5-foot sidewalk and a new catch basin are proposed for 156111 Ave SE. These improvements will be connected to the SE 2"d PL improvements at the existing sidewalk ramp . overview -Existing Conditions The property contains an existing house and detached garage, a large paved patio area surrounding a swimming pool, a gazebo and several outbuildings Including sheds and greenhouse, a graveled area in the SE corner plus a large lawn area and 3 significant trees. The property sheet flows from the NE to the SW corner. Surface runoff from the site flows down the driveway and enters a catch basin in 156111 Ave SE about 110' . southwest of the property. Flow then enters a 12" public storm drain and continues south . Conditions and Requirements Summary The project consists of creating 2 lots by short plat, retaining an existing single-family residences and detached garage on new Lot 1 and constructing a new house on Lot 2 after filling an existing swimming pool, demo sheds, replacing graveled area with lawn and one tree. The project will comply with the City of Renton short plat and storm drainage and utility construction requirements . Following review of the initial Drainage Memo submitted with the short plat application, the City placed their review on-hold pending resubmittal of the Drainage Report with the following additional information: Drainage repott: Please revise and resubmit the, drainage repott including the calculations. T71e existing conditions are to be modeled as forested conditions. Revise the, description accordingly. Additionally, mention the drainage review type as per the Figure 1.1.2.A (pagel-10) of the 2009 Surface Water Design Manual Amendment For Core requirement No. 2, it must include the description of the downstream' analysis and evaluation of the upstream drainage system (page 1-21) of the 2009 Surface Water Design Manual Amendment . ~ ,,<f't: f .. :, •. 1, '\JI. ;; ,..)J o'l~ ... .,~·"t>),t;~ 1:1 .. r · ~. ::12 t.nr: ·1? ~ .. :.' 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Based the proposed development new and replaced impervious area the development is subject to Targeted Drainage Review, see Table 1 and 2 and Figure 1.1. However, the City provided a copy of Figure 1.1.2.A showing a Full Drainage Review is required, see Figure 1.2. There was no supporting Information provided to illustrate the City's determination . p.:-... :1 v\::sijvt, 9."A.>z~l~i.11J . ~ ~ t·,~:,ti .A.t::.l.r ~rn,,:,i"i 'ti J•,;.rb "'"i,,,J=1!, :;i bsnrJ:i,,, c.:s_:,,;~ r•,i1i;t,:6v'.J srt! t.9v·o1lol-cdJ ?: m·Y,IC,, ,f, ,v,·:O i··r·; r,.:>,G .::uof'J ,::irimi b:.>:.>r;lqs~ l;,1i:; \'l'1f' 1':smqo;:,v:,1, b:,wqo1q 'J;~j srL ,13v:.:v·v}H . .t.1 'J ,ug~:.i l.ic1c ~ br; .. :; 1~ '-1\dr) \4 ~:.~ ~ , 1:'{;\\~~~,:--~ ·:1n~.r\iGJ(l_t)~rl~!>~1{t c'j :i)~(rJL!~ s:i2 ,t,•.,·,iup:,1 2i W'.;11 ... 1 '.Tfiniu,o n,,,, s pni·w('r12 A.:;..1 .t :,,ug;:110 ·1qo:i s b!ltJivo1q yJiJ ~··1iD sri.! 9:is t:iJlli o: ';3hivn1,~ n:Ji'r:;rn-orni Qnii1oq•1u?. or, 2-;,w ::i1::rlT .£.1 ci1U~il .r ,, ;/'!i:iniil ,·,.,,J,-b • • . , • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • ------------------------- Table 1 Mair Short Plat Figure 1.1.2.A Determination of Drainage Review Required Area Summary Table Exist. Pre-Dev Conditions (SF) Developed Conditions {SF) Single Lot Lot 1 Lot2 156th Ave Lot 1 Lot2 156th Ave Total Area 26,858 17,208 9,650 1,124 16,545 9,650 1,787 Pervious 16,542 10,198 6,344 100 9,588 7,050 Impervious 10,316 7,010 3,306 1,024 6,957 2,600 Total New and replaced Impervious Area is 3.478 SF There is no new impervious area. Instead, the project reduces the impervious area by 901 SF Refer to Figure 1.1.2.A The proposed Mair Short Plat consists of the following: Yes 1. The total new or replaced impervious area is 3,478 SF >2,000 SF Yes 2. The project results in less than <5,000 SF of new impervious area Per Figure 1.1.2.A chart, the Mair Short Plat is subject to a Small Project Drainage Review Is the project subject to a Targeted Drainage Review? No The project is not impacted by flood, erosion, steep sloped.hazard areas nor documented drainage problems Yes Project proposes to construct or modify a drainage pipe greater than 12" Therefore a Targeted Drainage Review is required . 909 878 r---·-.. ·------------------, :=;j;,, 1------------· --· --------····-·-··I ---------f;°;j,I 1•r11?;,r.~·---·---•-----·-------, ------·••-' --·--.. ~ -· -·H----·----.,_,._.,_ -~--: h .i,i~:1 13H VJ";\:'4 :f~:'!i"-··-,··.t, tr1·1;+ ., :,111:1:1(1 ~ <: : .1 '1Ll~i-l_ -----,_ .. --·' -::::-~.K's' If' I ._'J d\ ,•'j( •Vl':. rr11 ! ;...,., ~1 .,.)1,1, .•'·"')!~ :G!(· j" :~_''!t~·:rl 1'.<1• .,,.1l•·1.,q ·iJtl~. ·,,')•J,tL•0·:t d1,".i:-i1~i+l .r.ci,r~L'":•,..·:•i"li,·i')0.i.•.1.·:.:·•_r'r 4. .. 1 .I ..• w.·: ot 19J0h -----·-~ ..... ---- .• ;n .• \J ·,t ,.n_. r.i .··~1 1 UJ 1t1ri; ! ~~~ ·1!::..M ;:)?.nq(,··q '.ir!T ;~ ;',Q~•. '• ' -\J ,;_' j I ''hi, •,·1·1 1,' .. tf,i lJ~i·t-.;1{,~•1 10 W~1.l lGj(;.1 '1'.'.T _ _?~"Jr l. _.,·,:1 ?.UC"1'.;-, .... Jr11i ',• :, 10 =ir~ \, \t.1. , •n-.11J ,1 .. 1! 11. o!!1il.,,•·: .~,l·.to· (; ::,,fl .~.-~:;;.'~ ·t,e ·.-~ .. :·;--J.S.Il!-·'.:-';.~:;_-.<n"l).~~! ti o:· •·,·1l'-' ·· t.1 !'51'-, 1"r,ri1 ~it 1•11 ..::::,·: ,t'H .~-. \.~ I.f _ "1Jd ·,~r: I •f,'·/1 -~n ~~\[,"!l::~C ,~9-f n:c·t f ,;'· rutCu .. '.~._.J1'1 'J •; ·.! Y:~ _it1l•_ ~f,', :, ,, } •. ~, .. bif :· ri_;--, '..101,?. q•}':J't~, ('!~/ )1~' ,b.,u!' \'-' •:v ... ;_;,lj,-1<r-1i ,+l''l ..:~ ::>•,!.; ,r; I' r c.Ji c~11}•?kft,-.fi ')••, j 1.:1·1 '':-.I tli ... rf r\l£:i1:~ 't•·~· '3,.'.'..nu~di r) v .~.or:; -:v tJi~ i);111o·J c'• · ');0,.1,y-q 1Y_)l1,1Cl: -~)_Y ·~--11~rY1 ,:j V'~_,•_J~f· ~,~r:i~lC' ~:~t_el}~:_ ~ ·~ s1nkn,i; · • • • • • • • • • • • • • • • • • • • • • • • • . , • • • • • • • • • • • • • • • • • • • , . • •~ • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Table 2 Mair Short Plat Land Use Area Table (sq. ft.) Including 156th Ave SE improvements from Curb Face to PL Existing Proposed Summary Pervious 16642 Pervlous Impervious 11340 Impervious Total 27982 Lot 1 Area 17208 Lot 1 Area Pervious Pervious Landscape 1019! Landscape Impervious Impervious Pavement Pavement Sidewalk/stairs 386 Sidewalk/stairs Driveway 2320 Driveway Patio & Pool 133~ Patio Gravel 130 Gravel Retaining Wall 0 Retaining Wall Buildings Buildings House 1790 House Deck 31L Deck Garage 740 Garage rotal Imp. 7010 Lot 2 Area 9650 Lot 2 Area Pervious Pervious Landscape 634i Landscape Impervious . Impervious Pavement Pavement Sidewalk 172 Driveway Patio & Pool 475 Gravel drive 1924 Buildings Buildings Sheds 660 House Gazebo 75 Total Imp. 3306 156th Ave Area 1124 156th Ave Area Pervious . Pervious Landscaping 100 Landscaping Impervious Impervious Pavement & RT Wall 1024 Pavement 17547 10435 27982 16545 9588 386 2232 126; 130 105 1790 310 740 6957 9650 7050 600 2000 2600 1787 909 878 ... ~-· -,..-~ I ,--- ' ,·· ---·---···-·-·· .. ,---~---··-·--· ---·--·-. • • • • • • • • • • • • • •· .I • • • • • • • • • • • • • • • • • • • • • • • • • • • • • ~-------------------------------------------------• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • SECTION I.I DRAINAGE REVIEW FIGURE 1.1.2.A FLOW CHART FOR DETERMINING TYPE OF DRAINAGE REVIEW REQUIRED Is lhe project a slngle family resident/al p,oject that results In :.2,000 sf of new and/or ,ep/aced lmpe,vlous autface or ~7.000 sf of land disturbing activity, AND meets the following aiteria? SMALL PROJECT DRAINAGE . . REVIEW-0 • • • Section , : 1.2., • The project results In ~5.000 sf of new Impervious sutface, and ;;35,000 sf of new pe,v/ous sutface .•. Nate: Th& p1ojectJnay Blso be subjed ~'.TBITIJ'ted pra1ni,ge · Rev/9w as d9!ennined belovp Does lhe new or 18development p,oject result In ~2.000 sf of new and/or ,ep/aced Impervious sutface or ~35,000 sf of new pent/ow, sutface? Yes ( ) ( ! I '-, Does the project have the charecte~sUcs of one the followtng categooes of projects (see more detailed threshold language on p. 1-13)? 1. Projects containing or adjacent to a flood, erosion, or ate6p slope hazard area or documented drainage problem; projects within a lands/Ide hazard area or landsllde hazard drainage area; or No projects that propose ~7.000 sf (1 ac W project is in Sman_Project 1---+ Drainage Review) of land disturbing activity . ·2. Projects proposing io consfl'Ucl or modify a drainage pipe/ditch that is 12• or larger or receives runoff from a 12• or larger drainage plpe/dttch. - No/ Reassess whether drainage review Is required per Section 1.1.1 (p. HI) . / (Yes .. ! ) ;,·, . Does the project result In ~ acres of new Impervious sutface within a subbasin or multiple subbasins that are hydraulicaHy connected? NO -•",;c »,\,<'~··.,;/:,. -. :·,,;, FULL DRAINAGE RllVI.EW-. ~1,1.2.3 ·., ..... ···.,; _,. ·-· Yes ·; .. .. , ---1 ,.-- Cily of Renton 1-10 2009 Surface Water Design Manual Amendment • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • SECTION I. I DRAINAGE REVJEW FIGURE 1.1.2.A . FLOW CHART FOR DETERMINING TYPE OF DRAINAGE REVlEW REQUIRED 1s the project a single fanilly l8Sldanlml p,oJectlhat !99UltB In :J;ooo sf of new and/or replaced /mpelV1ous surface or :>:7,000 al of /enddlstumlng actMty, AND meets the lo!lowlng crttena? • The project resultll In "5,000 al of new lmpervloua sulface, and ~.000 Bf of new ,-v/oUtl SUtface Does the new or radeYelopmant pn,Ject resul1 In l!:2,000 al of new and/or ,eplaeed lmper,IOus sutface or l!:35,000 sf of new pen,low aulface? No Does the project have the chsracler1stlc:B of one or more of the follc,wlng categories of projecla (see more delal1ed tlueshold language on p. 1-13)? 1. Projecla containing or adjacent 10 a flood, erosion, or 8lll8p slope hantd anNI or documented drainage problem; projec:18 within a lands/Ida hazard ania or /andsJlde tma!fl dreJnage aree; or projeda that propoaei!:7,000 af(1 ac If project la In Small Prcject Drainage RevleW) of /and dlstu#Jlng 111:fMty . 2. ProjeclS pn,poaing 10 -or modify a dral"-pipe/ditch lha1 Is 12" or larger or l1I08MlS runoff from a 12* or larger drainage plpa/dltdi • No Reaasasa whather · drainage review Is requlnld per Section 1.1.1 (p.1-8) . ,.. Does the project result In :,so IICf88 of new /mper,lous · a-. w11111n a aubbasln or multfple aubbaslna the! are hydrauUcally connected? Yes City of R<:nlon 1-10 / • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • SECTION 2 Condition and Requirements Summary Core Requirement No. 1: Discharge at Natural Location The present property has a single discharge point to 156111 Ave SE at the SW corner . The surface runoff flows to the paved shoulder entering a catch basin and public storm drain system approximately 110' south of the property. Runoff from proposed Lot 1 will continue to discharge to the 156111 Ave SE public storm drain but be collected in a new catch basin located at the south property line . Roof and driveway drainage for proposed lot 2 will connect to the public catch basin located in 156111 Ave SE. A small portion of the driveway runoff will flow to a City catch basin in SE 2"d PL which discharges to the Evendell plat detention vault. The vault outfall discharges to the SE corner public catch basin mentioned above and connects to the "bypass" storm drain system in 156111 Ave SE . Core Requirement No. 2: Offsite Analysis The upstream areas surrounding property to the north, west and east are developed with single family housing, road frontage improvements and storm drainage systems including detention facilities. Runoff from the site sheet flows to the SW entering 156111 · Ave SE. Analysis of the offslte runoff patterns for 156111 Ave SE are described In Section 3 . Core Requirement No. 3: Flow Control The site falls within the City of Renton Flow Control Duration Standard (Forested Site Conditions). Including the required frontage improvements on 156111 Ave SE which results in a reduction of existing impervious area, development of the site reduces the combined imperious area by 905 square feet. The bulk of the reduction will be on Lot 2 where several sheds will be removed and a patio and pool and large gravel area will be replaced with landscaping. See the attached Land Use Area Table; Table 2 . The existing pavement on 156111 Ave SE extends approximately 28.5' east of the center line. With the proposed frontage improvements, ttie half-street pavement width will be 22'. Considering the 0.5' curb and 5' sidewalk, the new impervious width will be 27.5' or l' less than existing. Therefore, constructing the frontage improvements will have the effect of reducing the impervious area along 156111 Ave SE by approximately 140 square feet. The existing impervious area on Lot 2 is approximately 3,300 sq. ft. Existing Improvements will be removed including a large gravel area. The new house and driveway are expected to be approximately 2,600 sq. ft. Therefore, the proposed development will reduce the imperious area by about 700 square feet. Since this 1 tl;~'.". .. 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'i . ·,.: ifJ~ ~t _; '{l·:1!6:l1T >1,.,/~·, I!'~ :i2 c-,·/1\ ··rt: f 1!.i1.· , sg~s ""''. oi~n..Jqrni 9/j p, .. JUOS>1 ·!.., lJ911n JSSt ,;n1j2i;<:'. Jt ·)~ :';~)C,t y19:fi5fn!KO"!GC,1.~ 2; ~: ·toJ :io 6016 2Li01\n~,cp,ii ~1,1jt?1r. f)riT b:1h ~1?1, :r1 1.'/f~ :-, ··)rl' t ,;/·J-li.J' f1~,1 r:·1p 1/ ~ii d 1r1i·. 1:1:~ ... : i b~1v(1 1T1·i1 ~::-,:~ !!iw ,;in':1.lV.JVO ;qrni c)'. •c:,o.;i ·· iJ , ·.,r ',.·'i ),·l'f .,·r i;, cl(;i; I" Vic ,r.rnr(n· C'.11., :,,j c.t t.<ltYllJ'.3 .. ,;,; y:;wJ\ilb ?it l j 1~.t~~ . :,~-, -'JF.t .. c,2 l,(;\ JUfJC ,:; . (I . .;/'1C :·uol·13qr·qi ~fij ~1.J~ ·O· J 1 Iii:. :!"191 flGPl:;vzib • • • • • • • • • • • • • • •• • • •: • • • • • • • • • • • • • • • • • • • • • • • • • • • ; . • •• • • • • • • • • • • • • • • •• • • • • • • • • • • • • • • • • • • • • • • • • • reduction is less than the 5,000 square feet threshold, the project is exempt from storm water detention or water quality. A Restrictive Covenant will be provided to limit the impervious areas . However, as required in the City's on-hold notice, runoff calculations are provided in Section 4 based on routing the Lot 2 generated flows through one of the existing detention tanks fronting the site, which have excess capacity . Runoff from the development will connect to the "existing" storm drain system · constructed as mitigation for the Highlands Estates development. There does not appear to be any over topping or erosion within this public drainage system . Core Requirement No. 4: Conveyance System A wet vault and two detention tanks are buried in the 156th Ave SE pavement fronting the property. Access Manholes, vents and. grates will be raised, as needed to accommodate the proposed 8' planter strip. The vault located in the NW corner inclucles three large grates which receive surface runoff. Raising these grates in the planter strip would prevent street runoff from entering the vault. This vault was installed before construction of 2nc1 Pl SE. It appears that the new catch basins installed at the intersection by the Evendell development now collect the street runoff that would normally flow to this vault including the flow that passes over tlie "local system" CB's . Therefore, the actual tributary area to the grates is minimal. During project design, we will discuss with the City the need for providing open grates and/or a new catch basin connected to the existing vault. The only new public storm drainage facility installed for this project is the proposed new catch basin at the SW corner of the property. This catch basin will serve to intercept and capture surface runoff from 156th Ave SE and sheet flow from Lot 1. Since these flows already exist and are presently discharged to the "bypass", the new catch basin will also be connected to the "bypass". However, should it be required per the amended SWDM, this catch basin can be connected to the "local system" via second new catch basin in 156th Ave SE that will intercept the 12" pipe between Tank No. 2 and Tank No.1. Runoff from the new improvements on Lot 2 can be connected to the new City catch basin in the SW corner of the lot, if required. See further discussion in Sections 3 and 4 . Core Requirement No. 5: Erosion and Sediment Control Typical erosion control measures based on Best Management Practices will be shown on the engineered plans when submitted for the utility and roadway improvement permit. The site is currently fully developed with landscaping, a paved driveway and patio, a swimming pool, a house and detached garage and out buildings. 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T,) BfnO) Vi? '.,(jj (li n•2sd rL1jfjJ yJ:J J~ 1)1 •fi ~ ;:n,JjjJ':)2 if'·~· ~1..~ \ 1·nehnt;~s:t ~,ns no!:::o-·?:i ·~ .of:'J 1-r~:!-~'tfr.1 .. Jt~t19f1 s1{)J rio nwr: :t! ::-ri lliv11 i=:·; .... ;~iJGl"-l ·1:1::11 i~,:.101,sf/i 12·-,:J no t..:.. ::t:cl :~cj1iJ?69ffT !0-··1, ,,.)J : 1c1i-:o,~ lo:~1:i l('T . •, ·., ,'.·.c, 1',c r, .JV01<;'.1'., (b1,:~r;.)1 .Jns (;i';J!..l sr!:t m't 1:,e;Jim,Juz ncJrlw <''h"''< b9,:,1r1igno _,riJ G \l_v:r-,Q :.;r :-, yr;.· J':.. ·.11 :'J i. c,·,r,: ~I 11~. 1.:,GJd1r·-:-I rtti,,v b.:;qr.::1.sv'1b ·{:'.l 1t y:jns~·i:!J 2i 9ji~ !)ff1 nor 'L"S l)::,•,L•O'Jf 1 . ·:,i:)c::'.·t· ., JUC· bni: 9 :;,,1<ii,i borb.:J:Ji:' Jr,;; !'J2Uflil 6 ,!V)Q qnimffllVJ3 ::; ... Jr;.r_L!'JI i ·3 0.J.~ ~rj11_1J:/J r;,·. 'i, ti;! ti ·:i·,:)r)1 -;,: fEfT,;~1irr1 ~d ·~1 b9:~:,g(~)(•) !:"ib ;:"')"IUdSc:01 k>11f!O'.) • • • •• • • • • • • • • • • • • • • • • • • ' .! • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Core Requirement No. 6: Maintenance and Operation An operations and maintenance manual for the catch basins, conveyance pipes, and dispersal trench facilities will be prepared for building permit submittal for Lot 2 . Core Requirement No. 7: Financial Guarantees and Liability Financial Guarantees may be required for frontage improvements . Core Requirement No. 8: Water Quality As discussed in Core Requirement No'. 3, this project is exempt from water quality control requirements . However, as discussed in Section 4; a dispersal trench system may be provided to treat the driveway runoff if, based on the amended storm water design manual, the City determines its required . Special Reports and Studies A Geotechnical evaluation of the property is attached to this memo. Information was used.from the following TIR's for this report: • Highlands Estates Technical Information Report, by Haozous Engineering, P.S . dated January 9, 2004 • Technical Information Report for Saddlebrook Preliminary Plat, by DRS Consulting 'Engineering, Inc, dated August 27, 2012 Other Permits A building permit will be required for the new house on Lot 2, as well as a right of way permit to construct the curb and gutter, planter strip, sidewalk and utility connections to the water and sewer and existing public storm system . ·; }=.~.iJ: ,,r, :~ .1,...-· ·.:· .·tr,~·ia5rHs~t .;. .. c~11 ::~stT,s·Jr:.:r:-~~ fr,r.1::-- ,r1b ,-_ · .21•·, :.=r ... ;i:;v !ViiC, . .-~,;;. '";1 1 r!::1,:i~ i::.rU .1"'1 ii:i'Jr;r.r.1 :1:·n-s;·:.sJ·-1!6i-; t;:,:) ,_,1 ,·1iJJ:·;=1f10 qf'. ...... J(•.1 ·1ci \ :Jif":"'iJ~, ~ -;j ... ,~1!:)(l ~1li1.~ia1~ .. 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'1•J.,~ ,~.,~ .111,1f".;1\.·, _ ·.1 ., .. ,·1c .... t.._, •;:;;.,,;:i, .;..lu • • • • • • • • • •1 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • SECTION 3 Off-site Analysis Upstream There are two separate, parallel storm drains in 156th Ave SE. They were constructed in the 2002-03 time frame by the Highland Estates (HE) plat (located west of the . property) as part of the offsite mitigation. One storm drain, the "bypass" was originally built to take flows from an existing road ditch north of the widening of 156th Ave SE at approximately 750 ft north of 2"d PL to 525 ft south. The parallel storm drain system, "local system" was constructed to collect storm flows from the widened roadway section along 156th Ave SE plus about 1 acre of off-street flows from properties to the east . These local flows are conveyed to a wet vault followed by two detention tanks installed in the roadway fronting the project site. The "local system" connects to the "bypass" near the outlet to the downstream detention vault approximately 90' S of the property . See Figures 3-1 to 3-4 for as-built plans . Subsequent to the Highland Estates 156th Ave SE improvements, two additional residential developments have been constructed which intercept flows that originally · entered the "local system" The new developments provide on-site storm water treatment and detention and connect to the "bypass" system directly. The following describes the changes to the "local system" inflows. See Figure 3-5 for the upstream drainage basin map that shows the areas that are now diverted from the "local system" . The full area storm system map is contained in Appendix A . Evendell Plat A storm detention vault installed as mitigation for the Evendell development is located immediately East of the property. This portion of the plat was under construction in the summer of 2005. Prior to construction, according to the KC topography, a small portion of the development would have contributed flow to the "local system" see Figure 3-5 . The Evendell Plat is 70 lots, however only 11 of these lots, private access tracts and one block stretch of SE 2nd Place drains to the Evendell vault. That means about 1.8 acres to the east of the site is mitigated for flow and water quality before discharging into the City storm "bypass system" in 156th Ave SE. A storm drain and a 10' deep catch basin crossing the SE comer of the property carries the vault outflow past the property to the "bypass " . The Evendell drainage system includes catch basins installed in SE 2nd Pl at the 156th Ave SE intersection. These catch basins intercept runoff from approximately 0.4 acres which originally flowed to the wet vault. 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L-1S::.c=:=,-------•=r~1-a-r:1. ----~-··~ .. -..... "'":'-~ g HIGHLAND ESTATES 156TH AVENUE SE ROADWAY AND STORM DRAINAGE PROFILE • • • • • • • • • • • • • • • • ::ii II< • •Z l>l 0 • II) 1-o .~ l>lZ • ~-..:= -~ • z"' • gig • ~8 • -~ :!: ~ • t.i • • l>lz "'0 .1-o • .... z '-1>1 ~..: • II< • ,,; • • • • • • • • • • • • • • • • S.L'IGVA .I.3:M. <13:.LVM.WHO.LS S:!l.LV.LS:!l «NV7H{)IH i\ H "' • I • ii •• ' ' ' 11 i, h 11 • I, t I ' ~ I ' I ,11 ji' •• 11 i! --·----r,_'I'_ - ---·==a"2: - ~ : , ; <· 'I: .~ : ' ' ' ' ' ' ' ii-' : ' ' ' ' 11! ~ . ' ':i .t-; I ! . ~ \ ,. ii .,. !l • 11 • 'I . ' I I ·' !'I i ,! • I ii 1,1 ) I -------... - I ·' i 1 q j ~ I I i i ,ii a : • I' " ~ iii i ~ I i• ,i l ; I 'I i LL I ii I 'I I ! !I I .;_ '11 I'. J dlili I • I I~ I , ' ,..,_..,....,. , 0 l . ~ f~ . ... :1 ' .. ! .. ~:: • • • • • • • • • • • • • • • • ::ii .. • . :z: "'o • .,, ... . " "':!;j • ~== -~ • z"" • gig • ~8 • ·'-' • :!~ u . • "' :z: "'o • ..;!,; :::;.tj • .. • en • • • • • • • • • • • • • • • • S'1IV.L3.0 3.DVNIVHO ONV S}INV .L N0I.LN3.J..3.0 S:!r.LY.LS:!r aNYTH9/H I! J 1111111 ! 11 ·' ! 1! • II i I •• 1 • • ii lti! & •,-, .. ~ ll I If•: ti ~~~-!~ • i i ,,_ ! . ., • ! • i I i ! ' ,,. i ' I ' 1! .. ·, i I I I • . .. --·----n_,_ ---·==--1:1'. -'" ........... 1 ...... . I fl i,, ii ii •. l • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Figure 3.5 -"LOCAL SYSTEM" DRAINAGE AREA iMAP t,i King County AREAS ELIMINATED BY SUBSEQUENT DEVELOPEMENT • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • I , ---··--·-------~77 :,~:Pc,~:§~ IS~--7;-:i-J,~~:~ :. 1 -1, j ·;:.::~~-"'~ -·--,·-7. ..-~ a a~ KW~'.ll'fll -,..... 1·' ,..... .. ~, °' •·r ;:::; ilU a:: ,, I ,11,1.1 . ' • .I • I I I I I I I I I • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • ,. ~ It Is worth. noting that during high storm events, Evendell CB # 53 at the NE comer of 156th Ave SE which is in sump condition with a thru inlet curb, probably captures the majority of the 156th Ave SE surface runoff as high flows can skim over HE CB's #40 and 38, see photos In Appendix C. . With CB#53 discharging directly to the "bypass", this condition intercepts additional flows that previously entered the wet vault through the three large grates on top of the vault, Saddlebrook Plats Toe Saddlebrook and Saddlebrook Division II plats are located along 156th Ave SE north of the property. Saddlebrook 14-lot plat plus the Division II 3-Lot development broke ground earlier this year. Per TIR by DRS Engineers dated August 27, 2012, the development was granted an exception to have the entire site drain to a single on-site detention pond in the SW corner adjacent to 156th Ave SE. Toe natural terrain would have approximately 1.8 acres of the 4.4 acre site drain that direction and the remainder going toward the SE corner. Toe new storm system for Saddlebrook plats intercepts the street flow north of the NE 1st St intersection and much of the one acre of overland flow that the HE "local system" was designed to convey to the wet vault and two detention tanks near the Mair property, see Figure 3-7 for the Saddlebrook Div II drainage plan . Toe outflow from the drainage pond is discharged to the "bypass". In addition, the first CB (#42 HE plans) on the "local system" was sealed off by the development. Now the 1st "local system" catch basin to receive flow is CB# 41. With the two developments intercepting flows, it is clear that the HE installed "local system" and water quality/quantity treatment facilities are underutilized .. The resultant impact is shown in see Section 4 with the computer runs Downstream Toe drainage system downstream of the property includes the downstream detention tank and the lower end of the "bypass" system. Toe two storm drain systems, "bypass" and "local system" combine into one storm drain approximately 90' downstream of the site. Toe existing sheet flow leaving the property enters a catch basin which is connected to the combined system about 110' downstream. See Appendix A for the downstream storm system map. Toe downstream drainage facilities are listed on Table 3 . '.tc ·. -,t"'O) 3!1: :1r·. 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Distance From Drainage Problems Site (ft) Structure Description Existing Potential Observation 7 Type 1 CB Sealed• None None No Flow 38 50'-8' Dia Detent Tank None None No Flow 100 12" LCPE to Type 2 CB •• None None No Flow 110 12" LCPE to Type 1 CB None None No Flow 174 12" LCPE to Type 1 CB None None No Flow 198 12" LCPE to Type 2 CB None None No Flow 297 12" PVC to Type 1 CB None None No Flow 325 12" PVC to Jype 1 CB None None No Flow 390 12" PVC to Type 1 CB None None· No Flow 475 12" PVC to Type 1 CB None None No Flow 617 12" PVC to Type 1 CB None None No Flow 645 12" PVC to Type 1 CB None None No Flow 958 12" PVC to Type 1 CB None None No Flow 1000 12" PVC to Type 1 CB None None No Flow 12" PVC to Rock Lined 1078 Road Ditch " None None No Flow 1107 12" Culvert None None No Flow 1127 Rock Lined Road Ditch None None No Flow 1163 12" Culvert None None No Flow 1184 Rock Lined Road Ditch None None No Flow Notes: • This CB connects the Evendell storm vault outflow to the "bypass" 25' to NW .•• The two parallel storm drains are combined at this CB . Date of Inspection: August 8, 2014 ·.J~·· 01 '2~ · •·~~ qyri _-1,,, ••! ·,1.-ull;'J'J :'.usv r.·1101,.. ::-Jt·:risvi ·Jrlt <.:;">snnt.; J".:: i.:11n ~ :2!:.h .. " . fl~, ·!~ !G; .. .,. cirr10.:t :,·,,-:; .:r:iJ:•b i"ffltJil jr/ib,f:·f O\.,·· :;r:· : • .rrJ~ ,B 1:v51.rA ·no1j::i':~ :ni ,,, J·tc;C' • • • • • • • • • • • • • • • • • • • • • 1 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • ------------------- SECTION 4 Flow Control There is excess capacity in the wet vault and detention pipes fronting the property with recent upstream developments intercepting flows from the 156th Ave SE "local system". If this project requires stormwater control per the amended SWDM, we propose the following improvements. The roof drains (carrying clean water) from the proposed ne.o house will be connected to a conveyance pipe that will connect to a new catch basin intersecting the 12-inch pipe between tank number 2 and number 1 on the "local system" at approximately elevation 450.0 feet. This will provide for the utilization of tl'le! under-used detention volume provided in tank number 1. Since the roof drainage is considered clean runoff, no water quality provisions are needed . To the extent that grades will allow, much of the proposed new driveway will flow to SE 2nd PL and be collected in an existing catch basin near the west side of Lot 2. Flow from this catch basin discharges to the Evendell Plat storm detention vault. This will permit conveyance to an approved water quality facility. The increase in flow volume and pollutant loading will be so small as to be insignificant. Any remaining flow from the driveway runoff will be collected in a catch basin and discharged to a small dispersal trench where it can be discharged across a lawn area before joining the flow from the roof drains. In the process of flowing across a grassy strip it will receive basic treatment before going to detention tank number 1. There are two options available to direct compensatory flows to the "local system" wet vault and/or detention tanks. One option involyes rerouting the Evendell CB's flows at the intersection of SE 2nd PL from the "bypass" to the wet vault. As noted in Section 3, the Evendell CB #53 probably captures overflow from the "local system" CB's during major events . The other option would connect Lot 2 flows to the existing Evendell detention vault outfall, CB #39A in the SE comer of Lot 2 and rerouting the downstream flows at CB #38 from the "bypass" to the "local system" detention tanks. This option would also include the captured street flows from the proposed new CB at the S end of the proposed new 156th Ave SE frontage improvements . These options will be discussed with the City during the design phase and a suitable alternative will be selected . To confirm capacity of the existing vault/detention facilities, runoff from storm events were passed through the wet vault/detention tanks based on three scenarios. The first KCRTS computer run Is based on the original HE design analysis by Haozous Engineering, P.S., July 16th 2002. To represent the combined operation of the wet vault and two detention tanks, it was determined that an equivalent 8' diameter tank 125' long ri:li·N 1(r19"C' ,q <.Jfii qr,.'"'-' 11 r..)CJ!,t :;i,:/rt5j9iJ :_:,·1,.; ).,,bl' :i::JW c-1 ,j fli \':ti:l5l.;GJ 2'.S.)l.;; 2i s·1~il T . 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Ltri.S • • • • • • • • • • • • •• .; .i • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • effectively reproduced the outflows found in the Haozous report. See computer run #1 and Table 4 for contributing areas. The peak outflow discharge is 0.44 cfs and peak reservoir stage Is 7.1'. The original printouts from the Haozous report are contained in Appendix B. · The existing inflows based on the revised tributary area resulting from intercepted flows by the Saddlebrook development were input into the equivalent tank. The peak outflows were reduced by 88°/o and the required storage capacity is reduced by 20% . See computer run #2 . The flows from Lot 2 were add. to the existing inflows with a resulting peak outflow of 0.18 ds and peak reservoir stage of 7.01 ft. See computer run #3. 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Existing Conditions: SubBasin KCRTS basin Till Forest name 156th Ave SE & offsite to 156th Exist 0 east 156th Ave SE & offsite l 56thSadlexist 0 reduced due to Saddlebrook develop . Mair S.P. Lot 2 Mairpredev 0.22 Mair Lot2 + 156th Mairl56thexist ·0.22 reduced D 1 dC d'. eve one on 1t1ons: SubBasin KCRTS basin Till Forest name 156th Ave SE & offsite to 156th Dev 0 east 156th Ave SE & offsite l 56thSadldev 0 reduced due to Saddlebrook develop . Mair S.P. Lot 2 Mairdev 0.16 Mair Lot2 + 156th Mair l 56thdev 0 reduced Till Grass Impervious Totals (AC) (AC) 1.36 0.13 1.49 0.45 0.13 0.58 0 0 0.22 0.45 0.13 0.80 Till Impervious Totals Grass (AC) (AC) 1.01 0.48 1.49 0.10 0.48 0.58 0 0.06 0.22 0.26 0.54 0.80 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Run#1 Highland Estates as designed with wet vault and dual tanks replicated by a single 8' diameter tank with similar volumes for the detention portion . ~ Help I Files -KCRTS I c::i I @ IE?lill Flow Frequency Analysis Time Series File:156thexist.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--------Flow Frequency Analysis-~~- Flow Rate Rank Time of Peak --Peaks --Rank Return Prob (CFS) (CFS) Period 0.153 4 2/09/01 2:00 0.349 1 100.00 0.990 0.090 6 l/05/02 16:00 0.192 2 25.00 0. 960 0.192 2 2/27/03 7:00 0.158 3 10.00 0.900 0.058 8 8/26/04 2:00 0.153 4 5.00 0.800 0.087 7 l/05/05 8:00 0.144 5 3.00 0.667 0.158 3 l/18/06 16:00 0.090 6 2.00 0.500 0.144 5 11/24/06 3:00 0.087 7 1.30 0.231 0.349 1 l/09/00 6:00 0.050 0 1.10 0.091 D Computed Peaks 0.296 50.00 0.900 ' I "' I 1 " ·">-· .~ .... ,. ""' 50% of the 2-year flow is 0.045CFS as the target on the low end; 50-year flow is 0.296CFS as the target for upper end . :i!J • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Flow Duration from Time Series File:rdout.tsf Cutoff Count Frequency CDF Exceedence_Probability CFS Y. Y. Y. 0.003 45792 74.677 74.677 25.323 0.253E+OO 0.008 6032 9.837 84.514 15.486 0.155E+OO 0.013 3647 5.947 90.462 9.538 0.954E-01 · 0. 018 2470 4. 028 94. 490 5. 510 0. 551E-Ol 0.024 1699 2.771 97.260 2.740 0.274E-Ol 0.029 679 1.107 98:368 1.632 0.163E-01 0.034 483 0.788 99.155 0.845 0.845E-02 0.039 213 0.347 99.503 0.497 0.497E-02 0.045 81 0.132 99.635 0.365 0.365E-02 0.050 51 0.083 99.718 0.282 0.282E-02 0.055 53 0.086 99.804 0.196 0.196E-02 0.060 70 0.114 99.918 0.082 0.815E-03 0.066 10 0.016 99.935 0.065 0.652E-03 0.071 5 0.008 99.943 0.057 0.571E-03 0.076 5 0.008 99.951 0.049 0.489E-03 0.081 3 0.005 99.956 0.044 0.440E-03 0. 086 1 . 0. 002 99. 958 0. 042 0. 424E-03 0.092 2 0.003 99.961 0.039 0.391E-03 0.097 3 0.005 99.966 0.034 0.342E-03 0.102 2 0.003 99.969 0.031 0.310E-03 0.107 1 0.002 99.971 0.029 0.294E-03 0.113 2 0.003 99.974 0.026 0.261E-03 0.118 J 0.005 99.979 0.021 0.212E-03 0.123 2 0.003 99.982 0.018 0.179E-03 0.128 1 0.002 99.984 0.016 0.163E-03 0.134 4 0.007 99.990 0.010 0.978E-04 ·0.139 0 0.000 99.990 0.010 0.978E-04 0.144 1 0.002 99.992 0.008 0.815E-04 0.149 2 0.003 99.995 0.005 0.489E-04 0.155 1 0.002 99.997 0.003 0.326E-04 0.160 0 0.000 99.997 0.003 0.326E-04 0.165 0 0.000 99.997 0.003 0.326E-04 0.170 0 0.000 99.997 0.003 0.326E-04 0.175 1 0.002 99.998 0.002 0.163E-04 0.181 0 0.000 99.998 0.002 0.163E-04 0.186 0 0.000 99.998 0.002 0.163E-04 ----End of File----- --------- • ~~ I ;e • • • • • • • • ;. I. ' i• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Hyd Inflow Outflow Peak Storage Target Cale Stage Elev (Cu-Ft) (Ac-Ft) 1 0.44 ••••••• 0.44 7.10 457.10 2 0.20 0.19 0.19 7.02 457.02 3 0.21 ....... 0.17 7.01 457.01 4 0.22 ******* 0.14 6.99 456.99 5 0.25 ....... 0 .11 6.85 456.85 6 0.17 ....... 0.05 4.65 454.65 7 0.15 ....... 0.03 3 .. 11 453.11 8 0 .14 ••••••• 0.02 1.69 451.69 Route Time Series through Facility Inflow Time Series File:156thdev.tsf Outflow Time Series File:rdout 5830. 0.134 5830. 0.134 5830. 0.134 5829. 0.134 5802. 0.133 4291. 0.099 2794. 0.064 1405. 0. 032 Inflow/Outflow Analysis Peak Inflow Discharge: Peak Outflow Discharge: Peak Reservoir Stage: 0.440 CFS at 6:00 on Jan 9 in Year 8 0.440 CFS at 7:00 on Jan 9 in Year 8 7.10 Ft Peak Reservoir Elev: 457.10 Ft Peak Reservoir Storage: 5830. Cu-Ft 0.134 Ac-Ft The following RID facility (tank) is the same for all model runs, as is the depth/stage/volume relationship. These are not repeated for the sake of brevity . Retention/Detention Facility Type of Facility: Detention Tank Tank Diameter: 8.00 ft Tank Length: 125.00 ft Effective Storage Depth: 7.00 ft Stage O Elevation: 450.00 ft Storage Volume: 5830. cu . ft Riser Head: 7.00 ft Riser Diameter: 12.00 inches Number of orifices: 2 Full Head Pipe Orifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 0.00 0.83 0.049 2 4.20 0.55 0. 014 4.0 Top Notch Weir: Rectangular Length: 1.00 in Weir Height: 6.40 ft Outflow Rating Curve: None -----, l e e :e e e e e e ie I :e e e e e e e e e e e e !e :e :e e e 1e e e e e e e e e e e •e e e e e e 'e Stage (ft) 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.21 0.34 0.48 0.62 0. 76 0.89 1. 03 1.17 1.30 l._44 1. 58 1. 72 1. 85 1.99· 2.13 2.27 2.40 2.54 2.68 2.81 2.95 3.09 3.23 3.36 3.50 Elevation (ft) (cu. 450.00 450.01 450.02 450.03 450.04 450.05 450.06 450.07 450.21 450.34 450.48 450.62 450.76 450.89 451. 03 451.17 451.30 451. 44 451.58 451. 72 451.85 451.99 452.13 452.27 452.40 452.54 452.68 452.81 452.95 453.09 453.23 453.36 453.50 Storage Discharge Percolation ft) (ac-ft) (cfs) (cfs) 0. 0.000 0.000 0.00 7. 0.000 0.002 0.00 13. 0.000 0.002 0.00 20. 0.000 0.003 0.00 27. 0.001 0.004 0.00 33. 0.001 0.004 0.00 40. 0.001 0.005 0.00 47. 0.001 0.005 0.00 145. o,. 003 0.008 0.00 240. 0.006 0 .011 0.00 347. 0.008 0.013 0.00 457. 0.010 0.015 0.00 572. 0.013 0.016 0.00 681. 0.016 0.018 0.00 801. 0.018 0.019 0.00 924. 0.021 0.020 0.00 1041. 0.024 0.021 0.00 1169. 0.027 0.022 0.00 1299. 0.030 0.023 0.00 1431. 0.033 0.024 0.00 1554. 0.036 0.025 0.00 1689. 0.039 0.026 0.00 1825. 0.042 0.027 0.00 1962. 0.045 0.028 0.00 2091. 0.048 0.029 0.00 2229. 0.051 0.030 0.00 2369. 0.054 0.031 0.00 2498. 0.057 0.031 0.00 2638. 0.061 0. 032 0.00 2778. 0.064 0.033 0.00 2918. 0.067 0.034 0.00 3048. 0.070 0.034 0.00 3187. 0.073 0.035 0.00 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 3.50 3.64 3.78 3.91 4.05 4.19 4.20 4.21 4.22 4.23 4.24 4.25 4.38 4.52 4.66 4.79 4.93 5.07 5.21 ·5_ 34 5.48 5.62 5.76 5.89 ·6. 03 6.17 6.30 6.40 6.48 6.55 6.62 6.70 6.77 6.85 6. 92 7.00 453.50 453.64 453.78 453.91 454.05 454.19 454.20 454.21 454.22 454.23 454.24 454.25 454.38 454.52 454.66 454.79 454.93 455.07 455.21 455.34 455.48 455.62 455.76 455.89 456.03 456.17 456.30 456.40 456.48 456.55 456.62 456.70 456. 77 456.85 456.92 457.00 3187. 3326. 3463. 3590. 3726. 3861. 3870. 3880. 3889. 3899. 3908. 3918. 4040. 4171. 4299. 4417. 4541. 4662. 4780. 4887. 4999. 5107. 5210. 5302. 5396. 5485. 5561. 5616. 5657. 5690. 5721. 5753. 5778. 5803. 5819. 5830. 0.073 0 035 0.076 0.036 0.080 0.036 0.082 0.037 0.086 0.038 0.089 0.038 0.089 0.038 0.089 0.039 0.089 0.039 0.089 0.040 0.090 0.040 0.090 0.040 0.093 0.043 0.096 0.044 0.099 0.046 0.101 0.047 0.104 0.049 0.101 0.050· 0 .110 0. 051 0.112 0.052 0 .115 0. 053 0.117 0.054 0.120 0.055 0.122 0.056 0.124 0.057 0.126 0.058 0.128 0.059 0.129 0.059- 0.130 0.065 0 .131 0. 071 0.131 0.078 0.132 0.088 0.133 0.100 0.133 0.112 0.134 0.126 0.134 0.140 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Duration Comparison Anaylsis Base File: 156thexist.tsf New File: rdout.tsf Cutoff Units: Discharge in CFS Cutoff 0.045 0.056 0.067 0.079 0.090 0.101 0.112 0.124 0.135 0.146 0.158 0.169 0.180 0.191 ~--Fraction of Time-----~----~Check of Tolerance~--- Base New Y.Change Probability_ Base New Y.Change 0.59E-02 0.36E-02 -39.3 0.59E-02 0.045 0.037 -16.4 0.37E-02 0.18E-02 -51.8 0.37E-02 0.056 0.044 -20.9 0.21E-02 0.64E-03 -70.2 0.21E-02 0.067 0.054 -19.7 0.14E-02 0.46E-03 -68.2 0.14E-02 0.079 0.058 -26.8 0.90E-03 0.41E-03 -54.5 0.90E-03 . 0.090 0.059 -34.2 0.62E-03 0.34E-03 -44.7 0.62E-03 0.101 0.068 -32.8 0.36E-03 0.26E-03 -27.3 0.36E-03 0.112 0.094 -16.3 0.29E-03 O.lSE-03 -38.9 0.29E-03 0.124 0.111 -10.3 0.16E-03 0.98E-04 -40.0 0.16E-03 0.135 0:129 -4.4 0.98E-04 0.49E-04 -50.0 0.98E-04 0.146 0.139 -5.1 0.49E-04 0.33E-04 -33.3 0.49E-04 0.158 0.151 -4.3 0.33E-04 0.33E-04 0.0 0.33E-04 0.169 0.175 3.3 0.16E-04 0.16E-04 0.0 0.16E-04 0.180 0.187 3.7 0.16E-04 O.OOE+OO -100.0 0.16E-04 0.191 0.187 -2.4 Maximum positive excursion• 0.016 cfs 10.0Y.) occurring at 0.159 cfs on the Base Data:156thexist.tsf and at 0.175 cfs on the New Data:rdout.tsf Maximum negative excursion= 0.035 cfs (-36.8Y.) occurring at 0.096 cfs on the Base Data:156thexist.tsf and at 0.061 cfs on the New Data:rdout.tsf ... "! 0 a, ... ci "' ... fn ci u. .... ~ ... .. 0 ... -en "' .c C! " 0 ., 15 "' C! 0 "' C! 0 0 0 ci 10 ·5 10 -· 10 -3 10 -2 Probability Exceedence Targetdur ¢ rdout.dur • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Run#2 Existing conditions with flow from the Saddlebrook Plats diverted to the "bypass" ~ Help/ Files • KCRTS .. l•=l@1-.1 Time Series File:156tbdev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates----~--Flow Frequency Analysis------- Flow Rate Rank Time of Peak --Peaks --Rank Return Prob (CFS) (CFS) 0.206 4 2/09/01 2:00 o. 441 0 .149 7 1/05/02 16:00 0.253 0.253 2 2/27/03 7:00 0.217 0.139 9 9/26/04 2:00 0.206 0 .172 6 10/28/04 16:00 0.203 0.217 3 1/19/06 16:00 0.172 0.203 5 11/24/06 3:00 0.148 0.441 1 l/09/08 6:00 0.138 Computed Peaks 0.378 , I rrr I Hyd Inflow Outflow Peak Target Cale Stage Elev 1 0.25 ....... 0.05 5.17 455.17 2 0.18 0.09 0.04 4.47 454.47 .3 0.13 ******* 0.05 4.76 454.76 4 0.13 ******* 0.04 4.20 454.20 5 0.15 ••••••• 0.03 3. 43 . 453.43 6 0.14 ........ 0.03 2.59 452.59 7 0 .11 ******* 0.02 1.59 451.59 8 0.12 ........ 0.02 1. 68 451.68 Route Time Series through Facility Inflow Time Series File:156thsadldev.tsf Outflow Time Series File:rdout Inflow/Outflow Analysis Peak Inflow Discharge: Peak Outflow Discharge: Peak Reservoir Stage: Peak Reservoir Elev: Peak Reservoir Storage: 0.248 0.051 5.17 455.17 4744. 0.109 CFS at CFS at Ft Ft Cu-Ft Ac-Ft Period 1 100.00 0.990 2 25.00 0.960 3 10.00 0.900 4 5.00 0.900 5 3.00 0.667 6 2.00 0.500 7 1.30 0. 231 8 1.10 0.091 50.00 0.980 Storage (Cu-Ft) (Ac-Ft) 4744. 4127. 4392. 3869. 3120. 2284. 1311. 1397. 6:00 on Jan 11:00 on Jan 0.109 0. 095 0.101 0.089 0. 072 0.052 0.030 0. 032 9 in Year 8 9 in Year 8 D -. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Duration Comparison Anaylsis Base File: 156thsadldev.tsf New File: rdout.tsf Cutoff Units: Discharge in CFS .-----Fraction of Time-----~---~--Check of Toleranocee--~~ Cutoff Base Nev ~hange Probability Base 0.026 0.19E-01 0.51E-02 -72.5 I 0.19E-01 0.026 0.031 0.14E-01 D.25E-02 -82.2 I 0.14E-01 0.031 0.036 O.lOE-01 0.70E-03 -93.3 I 0.lOE-01 0.036 0.040 0.83E-02 0.21E-03 -97.5 I 0.83E-02 0.040 0.045 0.68E-02 0.65E-04 -99.0 I 0.68E-02 0.045 0.050 0.54E-02 O.OOE+OO -100.0 I 0.54E-02 0.050 0.055 0.42E-02 O.OOE+OO -100.0 I 0.42E-02 0.055 0.060 0.36E-02 0.00E+OO -100.0 I 0.36E-02 0.060 0.064 0.30E-02 O.OOE+OO -100.0 I 0.30E-02 0.064 0.069 0.24E-02 O.OOE+OO -100.0 I 0.24E-02 0.069 0.074 0.20E-02 O.OOE+OO -100.0 I 0.20E-02 0.074 0.079 0.17E-02 O.OOE+OO -100.0 I 0.17E-02 0.079 0.084 0.13E-02 O.OOE+OO -100.0 I 0.13E-02 0.084 0.089 0. 96E-03 0.00E+OO -100.0 I 0. 96E-03 0.089 here is no positive excursion 8Ximua negatiwe excursio~ g 0.054 cfs (-61.4Y.) ccurring at 0.088 cfs on the Base Data:156thsadldev.tsf and at 0.034 cfs on the Nev Data:rdout.tsf New ~.ChanC; 0.018 -29. o·. 019 -36. 0.021 -41. 0.022 -45. 0.024 -47. 0.025 -49. 0.027 -50. 0.028 -53. 0.029 -54. 0. 031 -55. 0. 031 -58. 0. 032 -59. 0.033 -60. 0.034 -61. Q P,rnsed DU1t1fio11 Ani1lysis · KOUS GJ[g]~ .... C) CD .... C) U) .... en C) u. N 8-.... GI 0 I:!' 0) (II .c ~ u 0 "' i5 U) ~ 0 .., ~ 0 0 ~ Probability .Exceedence rdout.dur <> target. dur • 156thsadldev.dur o 10 ·1 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • RUN#3 Developed flows from Lot 2 discharged to detention tanks under existing conditions . $ Help/ Files -KCRTS /f-,~ ··-'·' .. "' ·l""J'r,t,; ,• l,c,,l@ll-1 ~ ·-~=------~-~----------------------~-~-~-~~----------• Time Series File:mair156thdev.tsf Project location:Sea-Tac -~Annual Peak Flow Rates~------Flow Frequency Analysis---~- Flow Rate !lank Time of Peak --Peaks --!lank Return Prob (CFS) (CFS) Period 0.154 6 2/09/01 2:00 0.310 1 100.00 0.990 0.127 8 l/05/02 16:00 0.203 2 25.00 0.960 0.185 3 2/27/03 7:00 0.185 3 10.00 0.900 0.139 7 8/26/04 2:00 0.167 4 5.00 0.800 0.167 4· 10/28/04 16:00 0.164 5 3.00 0.667 0.164 5 l/18/06 16:00 0.154 6 2.00 0.500 0.203 2 10/26/06 0:00 0.139 7 1.30 0.231 0.310 1 l/09/08 6:00 0.127 8 1.10 0. 091 D Computed Peaks 0.275 50.00 0.980 'L "' I • .:t • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • ation Comparison Anaylsis Base File: 156thexist.tsf • New File: rdout.tsf Cutoff Units: Discharge in CFS Cutoff 0.045 0.056 0.067 0.079 0.090 0.101 0 .112 0.124 0.135 0.146 0.158 0.169 0.180 0.191 ----Fraction of Time---~-'----Check of Tolerance---- Base New %Change Probability Base New %Change 0.59E-02 0.73E-03 -87.6 0.59E-02 0.045 0.029 -34.9 0.37E-02 O.llE-03 -96.9 0.37E-02 0.056 0.032 -42.0 0.21E-02 O.OOE+OO -100.0 0.21E-02 0.067 0.036 -46.9 0.14E-02 O.OOE+OO -100.0 0.14E-02 0.079 0.038 -51.8 ·o.90E-03 O.OOE+OO -100.0 0.90E-03 0.090 0.043 -51.8 0.62E-03 O.OOE+OO -100.0 0.62E-03 0.101 0.047 -53.3 0.36E-03 O.OOE+OO -100.0 0.36E-03 0.112 0.051 -54.5 0.29E-03 O.OOE+OO -100.0 0.29E-03 0.124 0.052 -58.1 0.16E-03 O.OOE+OO -100.0 0.16E-03 0.135 0.054 -59.8 0.98E-04 O.OOE+OO -100.0 0.98E-04 0.146 0.057 -61.1 0.49E-04 O.OOE+OO -100.0 0.49E-04 0.158 0.059 -62.6 0.33E-04 O.OOE+OO -100.0 0.33E-04 0.169 0.063 .-62.4 0.16E-04 O.OOE+OO -100.0 0.16E-04 0.180 0.066 -63.4 0.16E-04 O.OOE+OO -100.0 0.16E-04 0.191 0.066 -65.6 There is no positive Bxcursion Maximum negative excursion• 0.126 cfs (-65.6%) occurring at 0.191 cfs on the Base Data:156thexist.tsf and at 0.066 cfs on the New Data:rdout.tsf ::: P,rnsed Duration Alli1lysl'> · KCR IS GJLQJ~ ... <'! 0 (X) ... ci II) ... 00 0 u. N ~ ... 4D 0 21 "' Ill .c 0 u ci "' i5 ID 0 .., 0 Q ~ oo ___ _ Probability Exceedence rdout.dur ~ target.dur • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • APPENDIX A DRAINAGE AREA STORM SYSTEM MAP • • • • • • • • • • • • • • • • • • • • • • • • •1 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •· • • • • • • • • • • • • • • • • • • • • • • • • • • • • :!! :i: E i I I I ~ I I I I . ..,,., ' ' • J'- - • '-I I . -~; "': ... ,--. --:-,. Mair Short Plat Area Storm System I . I l • ;=::µ-·-$=· :;':jl r---+---_l1 I I - . . I • I 1\ ! I J. I -·-· - I 11.--, -.. __, " ·I I I • ' Ill . ' i . . 1 . , • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • APPENDIX B -HIGHLAND ESTATES DESIGN PARAMETERS FOR 156THAVE SE OFFSITE DETENTION/WQ FACILITY SCALE IN F££1' 0 200 400 HIGHLAND ESTATES TREATMENT AND DETENTION TRADE AREAS ,...._ - l r ! ! 1 . t ~f,?···:niv;;."lf::, 11·,;.:,~9c ~::r~.:\·:-c:;J ~:r..t1112<ll:i-'1 -e :,UGVi;;'q'lA l; I.!,. 1/,·; '.' ,;\ ,.!li l v;·., I I(!:! I ie·,1 lf :E :l'J,\ HT,)( I >lO": . ••, _,,... I ..... , . , ... .• A 'fi (1 .' f" . t1 . ,..: ,,, ' .r-, r I . ·:1., l.'l .. • .:'.l''i;l'!:t.S I: ' :!• . IV-!.: · .• ,' . J --· ~--------.. ----. • • • • • • • • • • • • • • . , • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 156th Avenue SE Retention/Detention Facility (PIPE2 and PIPEl) Swnmary of Design Data: Detention: Detention standards: Level 2 Factor of safety selected (%): 10 Onsite area draining to vault (AC): 0.27 (See Table B.3.1) Offsi te area draining to vault {AC) : l.11 (See Table 3. 3. 1 l Bypass area(AC): 0.11 (Figure B.3.1) Time series for target duration: 156pre (See Appendix C.2} one-half 2-year peak flow rate for target (CFS): 0.045 SO-year peak flow rate for target (CFS}: 0.296 Tim.a series for developed duration: 156d, 156off, 156':,y Water Quality: Water quality standards: Basic (See Table 4 in Sectioa 4) Treatment trade required? Yes Description of treatment trade: A 0.11-acre portion of 156t• Avenue SE bypasses the vault. An offsite residential area of 1.11 acres will be routed to the vault and treated in place of the bypass from 156'" Avenue SE (See Figure B.3.1) • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 1'able 8.3.l. Areu Contributing to l~th Avenue SE Vault and Point-of.Compliance Downstrum POC Offsite Residenlial Noc .. : l56Ch A,ailltl SE Bypass Toral IS6off 156cl 156b)' l.01 0.35 1.36 1.01 1.01 0.10 0.03 0.13 0.10 0.27 0. I I 0,43 Omvd att31 lre=utd ti W% illljlCl\lious 1111d 50% as the !<lrroul'Nlb1g c,c,-.er tyl)C . Table IU.2. Overflow Dalp . Sit I !6th A-•• SE Dmc:2/4/0l RID Fndllty: KCRTS FOcmamc: C..Uribulh>g Time Sai<S: O.'Cll!Dw......,...uract=: Efflctgtnt]I O\\dow IMICblRt: Q._(CFS): (KCll~ U-pcak ma:) TopoC°"111ol SUuclrrr< RJo:r (l'T) Min. Top of 5-(l'I) Uipladt Ell-RID l~.Nlt 156'oll 5.ISf oatlct control SINCtore rilc:r (Rl) - lliaer RI RbefRI .... 4!0.5 4'1,0 Dtsignllcad-~ Sm: 12 12 Racr (l'T) o.oo Prilllllly °"'-Rbet llord <Fn 0.22 l'rcdlootd(FTI ~ TCMBIR,qul"'1 F""""'"1(PT) 0.~2 -CupnQty fflC\'Uliva -<ED <Cl'Sl cm 0,00 450.S 0.22 1.00 •io., I.I I 0.38 1.49 I.I I 0.27 0,11 1.49 WSB (F1J 4l0.5 4l0.7 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 156u, Avenue SB Retention/Detention Facility (Ptl'l:2 and P11'E1) P1PB2 -Upper Storage Pipe -Inlet: to System Type ot Facility: Tan!t oiamet<1r: Tani< i,ongth: Sffoctivc Storage Depth: Stage o Elevetion: Storage Volwne: Riser Read: Riser Dl.=t<u;: N\Jlllbar of orifiees: Orifice t Height ( ft) l 0.00 2 3. 75 Vop r«itcll weir: Length: Weir llei.ght: outflow 11.;oting Curve: Detention Tank 8.00 ft 45. ft 7 .oo !t 450,50 ft 2099, cu. ft 7 .oo ft 12.00 inelles 2 Ola1118ta&" Un) a.a3 0.50 rull Head Oi~ch;,rgo (CFS) o. 0~ 9 0.012 Rectangular l.00 in 6. 40 ft tkine f.lpa DiAmeter !inf 4. 0 PIP!lll -Lolffl' Storq• Pipe -Outlet fram System Typo of Facility: Tank Diameter: rank Length: Effectiv<1 Storage Depth: Stage O ~lQvation: Storage VOLW>.e: Rlse.r Bead: Riser Dli>motor: Numoar of arifieos: Orifice tt Rei9ht 1ft) l · 0 .OD 2 ~. 65 Tap llo~eh Weir: Length: Weir Height: Outflow llo~~ng Curve: Detention Tank 8.00 ft 45. ft 1.00 !t 443.50 ft 2099, CU, ft 7. 00 ft: 12. oo ln<,hes 2 Diameter Jin) O.B4 0.60 Full Head Dl.~r:h~rgo (CFS) 1),051 0,015 Rectangular 1.00 in 6.Jo rt Non!! Upo Oinmcter {in) \ • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • ._ -f u -I I l.i: 0.300 -+-Target --a -Developed 0.200 0.100 "GI. "'9. -S..19,. . "1il-"t!l, -,;i.. 0.000 1----+---------f-"------...:::;;.:s.. __ 1.00E-45 1.00E·04 1.00E-03 1.00E-02 1.00E·01 1.0<M:+00 Proballlllty of Exceedence Figure B.:S.3. Flow Duration Curves for RID. Duration curves are shown at o downstream point-of-compliance on 156th A'JClUle SE.. Level 2 standards are met • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • ' AppendixC Photos of Evendell CB#53 and HE CB#38 • • • • • • • • • • • • • • ' •: •I • • • • • • • • • • • • • • • • • • • • • • • • • • • . - • • • • • • • • • • 1• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • HE CB#38 with Extruded Curb HE CB#38 with Wet Vault Grates across SE 2nd PL • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • -----------~-------------------------~ HE CB#38 and Evendell CB#53 Evendell CB#53 and HE CB#38 . Mair Short Plat -Lot 2 plus 156'" Ave SE Frontage Improvements Pre-project -Post-project conditions KCRTS Printouts 6 Land Use Summary rArea----1 TIii Forest1 0.27 ncresl TI II Pasture! 0.00 acres I TIii Grassl 0.00 acres Outwa sh Forest! D.00 acres Outwzis h Pasture 0.00 acres 0.00 acres 0.00 acres Outw nsh Grnss I Wetland! 0.00 acres mperviousl ~--~ IT 0181 -·---1 L 0.27 ~cres_ Scale Factor: 1. 00 Hourly Reduced TI I me Series: jMairtotalpredev Compute Time Series Modify User Input F ile for computed Time Series (.TSF) Also called just' 'predev". :"O L,nd ·us!! Suni~~·B .-Area--- TIII Forest! O.oo acresl ' T ill Pasture/ Till Grassl 0.00 acres Outw Outwa 0.1~ acres ash Forest\ 0.00 acres ! Outw sh Pasturell 0.00 acres nsh Grass: O'.cJO aaesj I Wethrndi 0.00 acres1 rilpCrviousL 0 .. 09 ~~e.~] r Total------~··· I • j 0.27 acres ~---- Scale Factor: 1. 00 Hourly Reduced I ' TI me Series: !Mairtotaldcv Comp~tc Time Se:rl~s· Modify User Input File 'for computed Tim'e Series (.TSF} Also called "dev l·,C) 1·12~·.1...;-l ? 1»1 I 1»1 I --~ @ Hdp I Files -KCRTS ":.:.;m, ... ' . r.LOW r·requency Analysis ------- Tiine Series File: ma·ir£otalpredev. Project Location:Sea-T.SC · · --'.-Annual Peak Flow R<:',tes---: Flow Rate Rank Tim.e of Peak (CFS) 0.017 2 2/09/01 18 :00 0.005 7 l/06-'.'02 4 :00 0. 012 4 2/28/03 3: 00 0,001 8 3,/24/04 19: 00 0. 008 6 l/05/0? 8: 00 0.013 3 l/18/06 ?O: 00 0 .. 011 5 11/24/06 4 :00 0: 021 i l/09/08 9 :00 Comp\lt.ed Peaks ' i. '" 1 -----·- ""' Hel / Fil~''. KCRTS. '<N p ,/!l '\\,JI ' Flow Frequency Analy~is Time Series File:mairtotaldev .. tsf Project location:Sea-Tac --Annual Peak Flow Rates- Flow Rate Rank Time of Peak (CFS) 0. 038 0.028 0.046 0.026 0 '.032 0.040 0.037 0,080 aputed Peaks " ! _____ ~--_ j 4 7 2 8 6 3 5 1 2/09/01 1/05/02 2/27/03 8/26/04 10/28/04 l/18/06 10/26/06 l/09/08 2:00 16:00 7: 00 2: 00 16:00 16:00 0:00 6:00 . ::.,'···:,,;;:,· :t:,,: : . , ..... ··; _,.,, , . '\: Lo .1 @I lirii13,;,,I .. ,· --------- ~sf ---...:·-F: loY ~requency Analysis---. --'- --Peaks --Rank . Return Prob (CFS) Period 0:021 1 100,00 0 .990 0.017 2 25.00 0 . 960 0. 013 3 10.00 0 . 900 0 ,012 4 5.00 0 . soo· 0 .011 5 3.00 0. 667 0. 00.8 6 2.00 Q. 500 0.005 7 1. 30 0 .231 0.001 8 1.10 0 . 091 0.020 SO.OD 0 .980 --Flow Frequency Analysis----- --Peaks --Rank Return Prob (CFS) Period 0.080 1 100.00 0.046 2 25.00 0.040 3 10.00 0.038 4 5.00 0.037 5 3.00 0.032 6 2.00 0.028 7 1.30 0,026 8 1.10 0.069 SO.OD 0.990 0. 960 0.900 o. e.oo O.Gp 0.500 0.23i 0.091 0.:900 , CJ . ' .,: C The 100-year peak flow rate of 0.08 CFS is still under the 0.1 CFS threshold for flow control requirement. ' . Kris Sorensen From: Rohini Nair Sent: To: Wednesday, December 10, 2014 10:36 AM Kris Sorensen Subject: Attachments: FW: sample KCRTS output for another project located in the Forested conditions area MairPreDev-PostDevKCRTSComputerRuns-Lot2 Plus 156th Frontagelmprov.pdf -----Original Message----- From: Cliff Williams fmailto:cliff@sitedme.com] Sent: Wednesday, November 26, 2014 10:53 AM To: Rohini Nair Cc: Kris Sorensen; 'Bob'; 'Chris Beckman' Subject: RE: sample KCRTS output for another project located in the Forested conditions area Rohini: The attached is the KCRTS printouts for the combined Lot 2/156th Ave frontage improvements areas. The runoff remains less than 0.1 cfs so our development remains less than the threshold. I hope this completes the drainage report. Thanks Cliff Williams, PE Development Management Engineers, LLC 206 714-7161 www.sitedme.com -----Original Message----- From: Rohini Nair fmailto:RNair@Rentonwa.gov) Sent: Monday, November 24, 2014 10:52 AM To: 'Cliff Williams' Cc: Kris Sorensen Subject: RE: sample KCRTS output for another project located in the Forested conditions area Hi Cliff, One clarification. Did the after project calculations include the impervious surface changes due to the frontage improvements on 156th? Thanks Rohini -----Original Message----- From: Cliff Williams fmailto:cliff@sitedme.com) Sent: Friday, November 14, 2014 1:37 PM To: Rohini Nair Cc: Kris Sorensen Subject: RE: sample KCRTS output for another project located in the Forested conditions area Rohini: Printouts as requested. Cliff Williams, PE 1