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SWP272071(4)
1 1 1 1 TECHNICAL INFORMATION REPORT on the FLOODPLAIN/STO1 RMWATER SYSTEM for 1 Customer Services 1 Training C enter 1 Site Development., Support Facilities and SW 16th Street Renton, Washington October 1992 Sverdrup C 0 R P 0 R A T 1 0 N 3300 Carillon Point Kirkland, Washington 9BOB3-9762 (206) 822-33M Page 1 of 2 King County Building and Land Development Division ' TECHNICAL INFORMATION REPORT MR) WORKSHEET PART 1 PROJECT OWNER AND PART 2 PROJECT LOCATION . .• DESCRIPTION ProjectOwner The Boeing Company Project Name ('jictnmPr ',eruirPs Training Address P.O. Box 3707 , MS 6Y-50 Location Center Site Development Seattle, WA 98124-2207 Township 2 3 N Phone Range 4E Pro)ectEngineer Andrew Clapham Section 24 Company B E&C Engineers pry Size 5 3.81 AC Address Phone (206) 393-7072 Upstream Drainage Basin size Nelson�t 93AC Low a PART 3 TYPE OF • • PART 4 OTHER Q Subdivision L] DOF/G HPA ® Shoreline Management ' Q Short Subdivision Q COE 404 Q Rockery © Grading Q DOE Dam Safety Structural Vaults Q Commercial © FEMA Floodplain O Other Q Other Q COE Wetlands Q HPA PART 5 SITE COMMUNITY AND DRAINAGE BASIN Community City of Renton ' Drainage Bast r�pringbrook Creek CHARACTERISTICSPART 6 SITE Q River L] Floodplain Spri ngbrook Zone A4 ® Stream Adjacent to Spri ngbrook Creek ] Wetlands Urban Disturbed Q Critical Stream Reach Q Seeps/Springs Depressions/Swales ® High Groundwater Table 0 Lake Q Groundwater Recharge 0 Steep Slopes Q Other 0 Lakeside/Erosion Hazard PART 7 SOILS ' Soil Type Slopes Erosion Pote teal J.rQsr �(eIDG�tes Urban giisturbed Max. 1.5% exist Low/Minima U U �rtN' Puyallup Silt Loam Max. 1. % exist Low MinimaT.1 -b.0 FPS (Grass thied) ' Q Additional Sheets Attatched 1/90 ' FIGURE 1 ' Page 2 of 2 King County Building and Land Development Division ' TECHNICAL INFORMATION REPORT (TIR) WORKSHEET ' PART 8 DEVELOPMENTLIMITATIONS REFERENCE LIMITATION/SITE CONSTRAINT ' Ch.4-Downstream Anaiysis Black River (P-1) Pump Station* ] Upstream Analysis Nelson Place/longacres Wary ' a a a ' ] Add itional Sheets Attatched *No Effect on Project PART 9 ESC REQUIREMENTS ' MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION FOLLOWING CONSTRUCTION L] Sedimentation Facilities ® Stabilize Exposed Surface ' FX7 Stabilized Construction Entrance En Remove and Restore Temporary ESC Facilities FX] Perimeter Runoff Control ® Clean and Remove All Silt and Debris [K] Clearing and Grading Restrictions ® Ensure Operation of Permanent Facilities ' ® Cover Practices Flag Limits of NGPES 0 Construction Sequence O Other Other PART 10 SURFACE WATER SYSTEM ® Grass Lined Channel Tank Infiltration Method of Analysis Pipe System © Vault Depression King County "HYD" ® Open Channel ® Energy Dissapator Flow Dispersal Compensation/Mitigation ' 0 Dry Pond ® Wetland Co n s t r u c tEl Waiver of Eliminated Site Storage 1 Wet Pond O Stream Regional Detention Mitigating F1 oodpl a i n Brief Description of System Operation See part 8 Storage Facility Related Site Limitations Additional tched Reference Facility Limitation PART 11 STRUCTURAL ANALYSIS PART 12 EASE.,.IE N TS/TRA CT S (May require special structural review) , ® Drainage tf,;. ,r..,._.... ® Cast in Place Vault Other Access Ease Retaining Wall Native Growth ti?il*a?s�q�e Rockery>4'High Tract EXPIRES 2/i2/ ' Structural on Steep Slope 0 Other PART 14 SIGNATURE OF -• • ' I or a civil engineer under my supervision have visited the site. Actual site conditions as observer were incorporated into this worksheet and the attatchments. To the best of my knowledge the information provided ' here is accurate. 'y""rD" 9 act Z FIGURE 2 J. David Benson, P.E. 1/90 #24186 expires 2 Dec. 92 BOEING CSTC Site Development LOCATION MAP 'b{IC'r Seattle Censer ■. \t,;- -_rr ; YIM ngewood $ �< tiu.♦� r p SeafCFe-�__ ; - Medina 5�o1\\\\JJ . ' M^ �_ Pike Place Market R 1 P A Com/n Cd 1 Bellevue iy Seattle Aouarumi Duwamrsh-— UnM.siry `G' Kingaom -YT L Beaux 4 90 e : 0 ATts Porni i` aki r L I 3. = 3 2 n �n� I Point _yaw SI.. 2 900 u b.on,s a Ts SW C 90(ANE si � �•+ � \ .� 3 • � � n<Bdlpvyt re 90 rJM w.v� M Cer �- , ° Cdk.p.nM ®.rF 4?`(e $la'R of �•••.r.,o-,sn s an ` g s 8 s o.as,� eoM s HST 2 f aF sT 8 r 5 1 / A tai ' 900 4- 0 $ M.iseum of a°r s 'gin\ «b�. yeM Issa uah+E Su~ — 9 White`'. S 99 R °tii w•r v W Dolphin Center n w«vvr Point z 167 _ ® 10 i a co �; s rxeM sr 1; ' 5 1 I(yvay �x M11use.m 0 .TM sr n sE neTH sT N 4 c 99 900 sw o w Riverton ' s z Burien Heiglt6 f \kwila 2 Point SPdhutSt R_ 2 r 2 t Beets o 518 405 wor«n �'0rh 169 rear« i 33:.-..ty 53 SEA-TAC +.�, e 4 fires ��> INTL %® �3`' 11 Tree `• 5 !° IRPOR 2 Vasiwn Point .. 6 5091� *moo o w sr167 rer« st fai1W00d + o T ~ �R 2 Ct0.r 0.D '(r.°, `ED Normandy s WPT,ST 5 515 a ` Park 5 -_ 181 PROJECT Sr sw Vashon T ® - s x Center 509 r Ea s 7 ° SITE °♦t+° 5 se weT« ST ' ST N> P°rtage Des 3`. nzM E sr 8 sw __ Moines- •,2 - ast«sr = $ , vas f3 516 = Burton S. z.ot« 9 Robinson ` Kent se 1.OM ST 4 Point Zenith In ♦ A 7.eM ST .�Od(forl�. \S� Saawarer� s Col o ♦ 1 l � 2 ` 4 o w 3 gg 516 �PJP1 ti ti 7 U C .1 277W ST 4 516 5 Redondo 1 s 77 s a r Comgton Fp sE 17eM sT c � Pant .tuoroo 1 167 _ «ero« we..D'< P ner WAY S ...., 7 5 Green — q 4 # ,N Dasn 4 5 >:- Communav = 18 - ' t I Dinh\ Dp'nt __ 6 509 3 181 _ eM Colbge r .. i„ Point is« sT SE 312M IT 5 £ 3w« e Park \\ ST SF n r .um BLACK or.rego r° o«D °a Bm Way wra ; Federal o Auburn ,?- Pant--- \ III< Sw P - .1 2 r 8 5 ew ' 3J.' 1B_ +r 3 i ■ ewu.«_.err � � 1 ♦^ r5M zT sw � Wnne nn er vaes 1'4 t Nis[oncal useum �µTEv � ' (WSDOT) Sverdrup Figure 3 1 i BOEING CSTC Site Development 1 VICINITY MAP 1 • RAILROAD •.. .�,•, •• ^� 1 '� ,' • �e� - ` Ate_ �� � •• : _ ���- BM I :� 13 i 4`� Golf Course T 30 _ �;�� �� Sewage ��V=sue; • .�- 00, posa M 16 aL �iri3 I PROJECT Q "-- - SITE g _ I .� Track �.. i I _ E n•I �BM 29 — � Reservoir (USGS RENTON QUADRANGLE) Sverdrup Figure 4 1 HN - .� t fir .��x � �mffis oa= - W IN _ _ d �- -• ITS wo BASIN Wo $ Et I I I I EXIST IN ga $ �� ffi kta ns"InI g � 1 seq. gra _..s °a ; ti(tXi6SBY3� ��7' w�. "."4-`'..: «..« ' •.... ,....' ». �! « .. r ✓: .<.aro.xaa�— ,,,, �x IEXISTING e \` _ - 1 _ ffi � \\ \� � ,� � � �.# � � �..+,-' �� �- Lam► © 0 �"7�© © 7m ■ ' - •:.. i�x�t.�l�iit'w1�'1 _t:Tr7raa ' STORM WATER BIOFILTRATION SWALE ' 25-04 ELECTRICAL 25-03 12"0 RCP SD OUTLET ' UTILITIES TO WSDOT ROW/+ SUBSTATION SCALE: NONE BUILDING 25-02 �► '� \ /�/, ' " - -405 COMMUNICATIONS BUILDING WETPOND ' I-405 -k u EXISTING 48"0 RCP SD BASIN — 8------ ---------- 25-01 A I CSTC' t L I PROPOSED 36"0 DIP SD BASIN SEE FIG 7 F(][ SPRINGBROOK STORM D RAi N .; ,: :::.;.. CREEK UR \ L __j BURLINGTON ' NORTHERN PROJECT RR TRACKS LIMITS STORM WATER ' 1_REATMENT/DETENTION NOTE: SOUTHERN EXTENTS OF DRAINAGE PONDS BASINS OA AND © NOT SHOWN. ' SEE FIGURE 5 FOR LIMITS. M; w W" m M= — 0 AUBURN, WA. 98002 ACCEPTANUTY ❑BELLEVUE, WA. 98007 TMoK" POST—DEVELOPMENT BASINS +a* BOE//V� ❑EVERETT. WA. 98201 „tcmnm 0 �. BAN I FIG 6 FAOLITIES DEPARTMENT ❑KENT, WA. 98031 CSTC SITE DEVELOPMENT ,,, ❑PORTLAND, OR. 97220 ■RENTON WA. 98055 TIR ❑SEATTLlr, WA. 98124 1 _ c5zo007'7.owe zaA0/I2/91 ' STORM WATER BIOFILTRATION SWALE 25.04 i ELECTRICAL 12"0 RCP SD SUBSTATION SW 16TH ST. 25.03 OUTLET TO WSDOT ROW UTILITIES SCALE: NONE BUILDING j - 25.02 - - 1-405 COMMUNICATIONS BUILDING 40 �— WET POND I-405 n EXISTING 48"O RCP SD ' BASIN BIOFILTRATION SWALE �,.. 25-01 L CSTC ' PROPOSED 36 0 DIP SD f BASIN - ' SPRINGBROOK CREEK {{ Pr OSF \ 1 t Z OF EIJW JURISDICTION BURLINGTON dI i ►I ► I III n ' NORTHERN RR TRACKS STORM WATER TREATMENT/DETENTION PONDS ° M71om °" I* ""O10M w -mmle '"" ❑AUBURN, WA. 98002 VU ACaPTMUTY WY O1d° � BOE ❑ S.W. 16th STREET DRAINAGE .Lot Fwa w• ' ❑BELLEE WA. 98007 III //VG EVERETT, WA. '6TN1 -� FIG 7 FACILITIES DEPARTMENT ❑KENT, INA. 98031 "'"°"m" °"'' °"" ' 1 CSTC SITE DEVELOPMENT O PORTLAND, OR. 97220 ■RENTON, WA. 98055 TIR ❑SEATTLE, WA. 98124 iC5X00056 DWC KCt/10 12 9-, �,jam,, • <- .��I��r .., '4�: .ai.V- '71�'{C+� '�1} .,✓...... R- ^ �• � Its\-`, t � '`c -v a \' y e f.tr• .yT e�•ti�, /�. • ►F�a�i0t � 1• �' ���, tsy-'� saf{-i. `tom �, �,,�•t�` `c� ~ 'G:.� � 2f ,,yyI��s.�i'"r, (j' ((� � 1���� }� "�t �, '� ! a1. � _ '��•.,:9P' y ;;sue h'�.!� fh , K ••�[^,�, y �: ty',< ' '';�t� °rl0%4+�+��" f�' �� �3".a�i'3y tM#_t1�'`a�.�" 'G`}s.� s�'?+;,I?i:,ti'C�S` n �4 � � ,,+.` �`i' �- - � 'yi � 1°>••"•7/� � p h' I 1 • k 1F�S,•°y''� I' rl a �a•jJ M y x �' Cf yy� }� 3 ^" �h�`!1�'}•7�!^� 4 � -." 'F' f�`, �'.r!1j�nrs a'� � � 97 ��� s J. - •r-t► n"i.'�• ' ik!� ��ti:+i,. �"�.~ �l Y^'i•'SV � Q11qfF., •erry*�p� "'�.�w. w•-_R��-.�'r_�'�FE�re*+��'�� ' w.:,�:�� •f �'!/ 4zj•G � �y, n, �,�t .�,��.y:� r.r'^.'" -^}- 2�4�,��L•NYp1W'L.." 1�:*w.^- • �. .,. y �aee.».,^� , •f+.n.�.. ,>,...__—. -'i�we.ee,wlYr"��r.;- :+stro.;\ -�_� r� ��•' � 7. ' < ~.a��°'•'{ / -.v1�f'3�!?fi�lA.1-''k+-+s'' �a s`��� }'� �;i 4;+1��•y l•4^ �, +n. .'!*'��' ''\ / t ""�°"` • 'M \ Iz^dRL4} r.; f�' [� y,.. ,t 1 ham' `^»'3.� 71• „� ,�,� . � �. j +;'.+�r,C. .� '�'�i :'�ll,c�,,,� err, '�`y•°`fa''�'f.-3=''�t� ��\i�ll�y �--.by � Le': ,e-vv �"!f':s's.�'� �a r.t. - , °et, :�.1�a.;/ ;A' y y ��..• P `•.,;� �yyn. :w .\y h' - •Y4•'•t�)„. � '�4 0 ,p�a y �; • '�� ;.t • �lafa n••L viti cf ��'i �� �'�� i" !4.� -'.`=..a �"'"j!111b A,�. "•►'"e0'�irr\• ,� !! lV„o`a .V.y'e�` rl�t.:� �\�- N . . � ,• !•�i`� L: '1.6' ,� � .t\ ?ugF � s Y ♦.nw 1'• t1 yM�� �.. t�. .�9,L` ��I � �'! �� r � 1'' � ! 4 y� �\\����'`w. '�•a� � ti®. ''7Ps���,.:�.. < II Sig 1 v� �� 1 �.1� ly�e.,y.1 +a++eK� 3`���,.°�",�.. '\ ��• it�p� . �'M i�� ^�P �`,�r. ! j r ,� -4�5. ��i� y, � 'M'y ��i�'�"3r�''Ti •4 �' �1�� r�� r ��~ � i��. �1�1 � • �� � k'��� ti. 1�4��.q•��+r. �.rec la :Y. --�- \ �-. � :`t d."fly; �' 6` ��� �rf: L��.. ` I a' �' ��� �q�sajylR'�7C,,Sy"?"\ . ���� F` 'Y`�. \`�� Y��/ r F�.n 2 i a(/,l �•• '; �+•x••',., \lay, •���'76 :4 ,.. � �j qt� .✓ .Ys° 7 ,��p,} /,// � w ��'+� \d�"•Ij' \ �� � � F .I14':.�.a � \ -1 r��� iy1 �1 \ 1'2� 't 9 �.At"` t'°i(f..i+...tlyR y .' ?, r' j11�.Iri �-�•' ./:'�p7 �,7 4s'�:,.�j, ► 1 --�•__ Is i �r� �'��� l' �.°�y "..liC< �;y N`_�- +•s•• .t•� \ �` n'1�•i �^4._"�s•� •,�.►••�r:ls. we•hi.wi.-,%�aG•.v.�'� -r..--.e. - .,,,.�_.�.+f:',�!d�.. .�'� �. � ��a ye91 i �' � ra•:.��^� fj 1 ♦ �' • _ •.y 4'•w1 11_•�I�.ft. �t� ~� t•� y`'may��i � a.+ r., cs.,,,�,. �a•r.. � .fir r. G ',..' .o- -�.+�� h _ �•►4,,� :� •��'j;A.:l�iT�ira' �.o�•v:.,.��g4.Cdrtr�d6� X'f *�`, _ I 1 • • i� UV 17 �� . r �,',�: ••.F= :.fir >p r=,,,, >� i3y u. A -qf� ` eb- hr 'T - . ""a Y+-*•. - ZONE X y FLOODWAY r MI 11 ••I :• I •MP 0 • I •1I • ' - • • • ' Geol Engineers April 29, 1991 Geotechnical. ' Geoenvironmental and Geologic Services ' Boeing Company P.O. Box 3797, M/S 13-03 Seattle, Washington 98124-2207 ' Attention: Mr. Andrew Clapham M/S 13-03 Geotechnical Consultation Potential Lake Impacts Boeing Longacres Park Renton, Washington ' File No. 0120-090-BO2 At your request, we have reviewed potential impacts to the site from ' the proposed lake at Longacres Park in Renton, Washington. General surface and subsurface conditions for the site are described in our report dated ' January 23, 1991. Boeing currently proposes to construct a lake within a portion of the existing racetrack infield as a part of the site development. The lake will ' be below existing surface grades, i.e. , be entirely in cut. The design high water surface has not been finalized at this time. However, we understand ' that the water surface will be no higher than Elevation 7 feet. Existing grades across the infield range from Elevation 10 to 16 feet. Field data gathered to date indicate that the water levels in the area of the proposed lake rise to an elevation of about 10 to 11 feet during periods of intensive precipitation. Therefore, the presence of the lake will not result in an increase in the ground water table above historic levels. The site has experienced occasional flooding. Thus, even if the outlet were to become ' plugged, any possible resultant flooding would not create conditions worse than what the site has experienced in the past. The Longacres site is relatively level and is situated in the Green River valley. Thus, there are no adjacent steep slope areas which will be adversely impacted by the lake. As the lake level will be no higher than ' historic high water levels, we do not believe there will be any adverse impacts from the construction of the lake on adjacent facilities. ' Geolingineers.Inc. 8410 154th Avenue V.E. Redmond.WA 98052 ' Telephone(206)861.6000 Far(206)861-6050 FIGURE 10 Geol Engineers Boeing Company ' April 29, 1991 Page 2 We trust that this letter meets your current needs. If you have any question concerning the contents of this letter or require additional information, please contact us. Yours very truly, ' r1� L. ;C, GeoEngineers, Inc. tom " Nancy L. ochko Senior Engineer Jon W. Koloski ' Principal NLT:JWK cc: /Sverdrup Corporation ' Attn: Mr. Dave Bensen LONGACRES PARK CSTC SITE DEVELOPMENT ' PRE-DEVELOPMENT AREA WEIGHTED RUNOFF COEFFICIENT #1 TUKWILA DRAINAGE BASIN ' (Area west of BNRR to West Valley Highway) Soil Hydrologic Curve Land Use Area Weight Weighted Group Group Number Description (SF) Curve Number ' Ur D 98 Building Roofs 199,206 5% 4.8 Ur D 98 Pavements 219,300 5% 5.3 Ur D 91 Gravel Parking Lots 55,080 1% 1.2 Ur D 90 Landscaping(good) 1,407,169 35% 31.3 Wo D 98 Building Roofs 48,300 1% 1.2 ' Wo D 98 Pavements 117,300 3% 2.8 WO D 91 Gravel Parking Lots 81,600 2% 1.8 Wo D 89 Meadow 1,020,247 25% 22.4 ' Ng B 98 Building Roofs 19,000 0% 0.5 Ng B 98 Pavements 53,500 1% 1.3 Ng B 85 Gravel Parking Lots 29,000 1% 0.6 ' Ng B 78 Meadow 148,665 4% 2.9 Ng I B 1 77 woodland/Meadow 648,188 16% 12.3 ' TOTALS1 I 1 4,046,554 100% 1 88.52 ' Notes: 1. Soil groups determined from Soil Survey, King County Area, Washington, Renton Quadrangle 1973 2. Hydrologic groups determined from King County Surface Water Design Manual Figure 3.5.2A ' 3. Curve Numbers determined from King County Surface Water Design Manual Table 3.5.2E ' Impervious area (curve number > = 98) _ 656,606 SF Impervious area curve number 98.00 ' Pervious area (curve number < 98) 3,389,948 SF Pervious area curve number 86.68 ' Drainage Basin #1 Curve Number = 88.52 Drainage Basin #1 Total Area = 92.90 Acres ' Not within CSTC project limits ' but currently drains through site Sverdrup Corporation Figure 11 1/11/92 ' CSTCDCN.XLS LONGACRES PARK CSTC SITE DEVELOPMENT PRE-DEVELOPMENT AREA WEIGHTED RUNOFF COEFFICIENT #2 NORTH OF SW 16th STREET ' (North of SW 16th Street, UB Complex-Site Only) Soil Hydrologic Curve Land Use Area Weight Weighted Group Group Number Description (SF) Curve Number ' Ur D 98 Building Roofs 30,393 23% 22.4 Ur D 98 Pavements 21,075 16% 15.5 ' Ur D 92 1 landscaping/wood(fair) 81,564 1 61% 56.4 TOTALS1 133,032 100% 94.32 Notes: ' 1. Soil groups determined from Soil Survey, King County Area,Washington, Renton Quadrangle 1973 2. Hydrologic groups determined from King County Surface Water Design Manual Figure 3.5.2A ' 3. Curve Numbers determined from King County Surface Water Design Manual Table 3.5.26 Impervious area (curve number > = 98) = 51,468 SF ' Impervious area curve number = 98.00 - Pervious area (curve number < 98) = 81,564 SF ' Pervious area curve number = 92.00 ' Drainage Basin #2 Curve Number 94.32 Drainage Basin #2 Total Area - 3.05 Acres ' Sverdrup Corporation Figure 12 4/6/92 i LONGACRES PARK CSTC SITE DEVELOPMENT PRE-DEVELOPMENT AREA WEIGHTED RUNOFF COEFFICIENT i #3 NORTH MAIN TRACK BASIN ' (From SW 16th Street to Center of Main Track) Soil Hydrologic Curve Land Use Area Weight Weighted Group Group Number Description (SF) Curve Number iUr D 98 Building Roofs 416,498 13% 12.3 Ur D 98 Pavements 462,380 14% 13.6 i Ur D 91 Gravel Parking Lots 230,345 7% 6.3 Ur D 90 Landscaping(good) 14,825 0% 0.4 Ur C 87 Sand Racing Track(dirt road) 231,825 7% 6.1 i Ur D 90 Lawns(good) 1,065,145 32% 28.8 Ur D 92 Horse Walking Areas(fair) 358,237 11% 9.9 Ur D 89 Meadow 261,460 8% 7.0 iPy B 85 Gravel Parking Lots 23,050 1% 0.6 Py B 80 Lawns(good) 39,962 1% 1.0 iPy B 78 Meadow 222,650 79/6 5.2 TOTALS 3,326,377 100% 91.15 iNotes: 1. Soil groups determined from Soil Survey, King County Area,Washington, Renton Quadrangle 1973 i2. Hydrologic groups determined from King County Surface Water Design Manual Figure 3.5.2A 3. Curve Numbers determined from King County Surface Water Design Manual Table 3.5.2E iImpervious area curve number > = 98 = 878,878 SF i Impervious area curve number = 98.00 Pervious area (curve number < 98) = 2,447,499 SF Pervious area curve number = 88.69 1 Drainage Basin #3 Curve Number = 91.15 iDrainage Basin #3 Total Area = 76.36 Acres 1 Sverdrup Corporation Figure 13 1/11/92 1 LONGACRES PARK CSTC SITE DEVELOPMENT POST-DEVELOPMENT AREA WEIGHTED RUNOFF COEFFICIENT (A) TUKWILA DRAINAGE BASIN (Area west of BNRR to West Valley Highway) ' Soil Hydrologic Curve Land Use Area Weight Weighted Group Group Number Description (SF) Curve Number Ur D 98 Building Roofs 199,206 5% 4.8 Ur D 98 Pavements 219,300 5% 5.3 Ur D 91 Gravel Parking Lots 55,080 1% 1.2 Ur D 90 Landscaping(good) 1,407,169 35% 31.3 Wo D 98 Building Roofs 48,300 1% 1.2 Wo D 98 Pavements 117,300 3% 2.8 Wo D 91 Gravel Parking Lots 81,600 2% 1.8 Wo D 89 Meadow 1,020,247 25% 22.4 Ng B 98 Building Roofs 19,000 0% 0.5 Ng B 98 Pavements 53,500 1% 1.3 Ng B 85 Gravel Parking Lots 29,000 1% 0.6 Ng B 78 Meadow 148,665 4% 2.9 Ng B 77 Woodland/Meadow 648,188 16% 12.3 TOTALS 4,046,554 100% 88.52 Notes: 1. Soil groups determined from Soil Survey, King County Area,Washington, Renton Quadrangle 1973 2. Hydrologic groups determined from King County Surface Water Design Manual Figure 3.5.2A 3. Curve Numbers determined from King County Surface Water Design Manual Table 3.5.26 Impervious area (curve number > = 98) - 656,606 SF Impervious area curve number 98.00 Pervious area (curve number < 98) = 3,389,948 SF Pervious area curve number = 86.68 ' Drainage Basin A Curve Number = 88.52 Drainage Basin A Total Area = 92.90 Acres Not within CSTC project limits but currently drains through site Sverdrup Corporation Figure 14 1/11/92 ' CSTCDCN.XLS ' LONGACRES PARK CSTC SITE DEVELOPMENT POST-DEVELOPMENT AREA WEIGHTED RUNOFF COEFFICIENT ' BASIN B ' (North of SW 16th Street , UB Complex- Site Only) Soil Hydrologic Curve Land Use Area Weight Weighted Group Group Number Description (SF) Curve Number Ur D 98 Building Roofs 22,501 17% 16.6 Ur D 98 Pavements 38,753 29% 28.5 ' Ur D 91 Gravel Sufaces(sub-station) 6,090 5% 4.2 Ur D 90 Landscaping(good) 62,048 47% 42.0 Ur D 98 Sidewalks 3,640 3% 2.7 TOTALS 133,032 100% 93.95 ' Notes: 1. Soil groups determined from Soil Survey, King County Area,Washington, Renton Quadrangle 1973 ' 2. Hydrologic groups determined from King County Surface Water Design Manual Figure 3.5.2A 3. Curve Numbers determined from King County Surface Water Design Manual Table 3.5.26 ' Impervious area (curve number > = 98) = 64,894 SF Impervious area curve number = 98.00 ' Pervious area (curve number < 98) = 68,138 SF Pervious area curve number = 90.09 Drainage Basin B Curve Number = 93.95 ' Drainage Basin B Total Area = 3.05 Acres 1 ' Sverdrup Corporation Figure 15 4/6/92 LONGACRES PARK CSTC SITE DEVELOPMENT ' POST-DEVELOPMENT AREA WEIGHTED RUNOFF COEFFICIENT ' (C) NORTH MAIN TRACK BASIN (From SW 16th Street to CSTC Project Limits) Soil Hydrologic Curve Land Use Area Weight Weighted Group Group Number Description (SF) Curve Number Ur D 98 Building Roofs 383,965 12% 11.3 Ur D 98 Pavements 750,200 23% 22.1 ' Ur D 91 Gravel Parking Lots 164,095 5% 4.5 Ur D 90 Landscaping(good) 1,073,213 32% 29.0 Ur C 87 Sand Racing Track(dirt road) 59,970 2% 1.6 PUr D 90 Lawns(good) 381,885 11% 10.3 D 92 Horse Walking Areas(fair) 16,800 1% 0.5 D 100 Water Sufaces 220,037 7% 6.6 ' B 80 Landscaping (gam) 151,300 5% 3.6 Py B 85 Gravel Parking Lots 23,050 1% 0.6 ' Py B 80 Lawns(good) 39,962 1% 1.0 Py B 78 Meadow 41,400 1% 1.0 Py B 100 Water Sufaces 20,500 1% 0.6 ' TOTALS1 3,326,377 1 100% 92.70 ' Notes: 1. Soil groups determined from Soil Survey, King County Area,Washington, Renton Quadrangle 1973 2. Hydrologic groups determined from King County Surface Water Design Manual Figure 3.5.2A 3. Curve Numbers determined from King County Surface Water Design Manual Table 3.5.26 ' Impervious area (curve number > = 98) = 1,374,702 SF Impervious area curve number = 98.35 Pervious area (curve number < 98) = 1,951,675 SF Pervious area curve number = 88.72 ' Drainage Basin C Curve Number = 92.70 Drainage Basin C Total Area = 76.36 Acres Sverdrup Corporation Figure 16 1/11/92 ' REBSWI6R.XLS ' LONGACRES PARK CSTC SITE DEVELOPMENT ' PRE-DEVELOPMENT AREA WEIGHTED RUNOFF COEFFICIENT ' S.W. 16th STREET RIGHT OF WAY ' (STA 34+85 TO STA 18+00 ) Soil Hydrologic Curve Land Use Area Weight Weighted Group Group Number Description (S� Curve Number Ur D 98 Pavement 54,560 40% 39.7 Ur D 91 Gravel Shoulders 80,240 60% 54.2 TOTALS 134,800 100% 93.83 ' Notes: 1. Soil groups determined from Soil Survey, King County Area,Washington, Renton Quadrangle 1973 ' 2. Hydrologic groups determined from King County Surface Water Design Manual Figure 3.5.2A 3. Curve Numbers determined from King County Surface Water Design Manual Table 3.5.26 ' Impervious area (curve number > = 98) = 54,560 SF Impervious area curve number = 98.00 ' Pervious area (curve number < 98) = 80,240 SF Pervious area curve number = 91.00 ' Drainage Basin #1 Curve Number = 93.83 Drainage Basin #1 Total Area = 3.09 Acres Sverdrup Corporation Figure 17 4/6/92 ' REBSWI6R.XLS LONGACRES PARK CSTC SITE DEVELOPMENT ' POST-DEVELOPMENT AREA WEIGHTED RUNOFF COEFFICIENT SW 16th STREET Right of Way ' ( STA 34+85 TO STA 18+00 ) Soil Hydrologic Curve Land Use Area Weight Weighted Group Group Number Description (SF) Curve Number Ur D 98 Pavement Area 87,620 65% 63.7 Ur D 98 Driveways 4,880 4% 3.5 ' Ur D 90 Landscaping(good) 42,300 31% 28.2 TOTALS 134.800 100% 1 95.49 Notes: ' 1. Soil groups determined from Soil Survey, King County Area,Washington, Renton Quadrangle 1973 2. Hydrologic groups determined from King County Surface Water Design Manual Figure 3.5.2A ' 3. Curve Numbers determined from King County Surface Water Design Manual Table 3.5.2E Impervious area (curve number > = 98) = 92,500 SF ' Impervious area curve number = 98.00 Pervious area (curve number < 98) = 42,300 SF ' Pervious area curve number = 90.00 ' Drainage Basin #2 Curve Number = 95.49 Drainage Basin #2 Total Area - 3.09 Acres ' Sverdrup Corporation Figure 18 4/6/92 REBI6FL.XLS BASIN 1 PEAK FLOWS ' STORM FREQUENCY FLOW (CFS) TOTAL PEAK RUNOFF PEAK THRU 24'CULVERT ' 2-YEAR 24-HOUR 16.04 1 -95 5-YEAR 24-HOUR 22.12 17.56 .. . .. ................................................................. 10-YEAR1.24•HOUR 30.14 3 49 25-YEAR 24-HOUR 38.48 21.29 5( -YEAR 24 H. 39 32 . .:.:.::: 21 100-YEAR 24-HOUR 47.01 21.73 ' io&-YEARI 28.73 2a:32 1 S.W. 16th STREET RIGHT OF WAY BASIN ' HYDROGRAPH PEAK FLOWS ' STORM FREQUENCY FLOW (CFS ) PRE-DEVELOPMENT POST-DEVELOPMENT INCREASE 2-YEAR 24-HOUR M92 1 05 0.13 _.. . 5-YEAR 24-HOUR 1.17 1.31 0.14 ' 10-YEAR 24-HOUR 149 1.63 0.i4 25-YEAR 24-HOUR 1.81 1.96 0.15 ' 50-YEAR,24-HOUR 1.85 1.99 0.14 100-YEAR 24-HOUR 2.14 2.29 0.15 100-YEAR 7-DAY 1.13 1.22 0.09 ' Sverdrup Corporation Figure 19 4/6/92 TKWLAPIP.XLC 48-Inch Diameter Tukwila Storm Drain Capacity 50 ......._----..........._�-----------------.._._.,._........................ ..... , ......._......... _......._............ - ._...............__I ._............ -; ................._. E ! t I i 3 45 i ......_..._ ` ......_...._._..... ` ......._._......... _...._.----- ..................... ...................... ._._._._._..--- i ..................... j ! I I 40 ..._................-- ........................._..............._._................................ .._...._...._........... z._............._...._ _..... ......_..... ._._..... j i I j ; i E 35 - ..................__._ ._..................._........................... .... ...._._..... .._._...._........ _..--------------------................ .................._......................_...........i..........................f............................................... I i ; 1 30 _...................._._._.. ................ ........................._... ......._._...._._. - -......_........ --..._............_ _.._................ _.. _......._ ......._......._._. i j i s ,... +...1.. 271 o I ._. .. ................... : _... FEMA 00-Year Mood El $ 16.4 ..._. .........._....:.._.....................;._.............._._._...;..........._._......._............._...._._..... _ __ .................._ _._...._ ..................E 20 .. ,..._ ...+... ......_................ V SCS 100-Year Fibod El = 1.6 I ? 15 --.....................I..._............._._..._............_........;._............_._._._.;..........._._._...._.........- ._._._...... _._._._._......... _...._._............_ �-_._..............._._ _._......... _._._.__ .......---...._._. ..._._._._._..... .._._._.............. E E .. ._ . ... Winter Nigh Flow El = 6.2 ........_.............. ..... .... E Summer Sustained Flow El = 3.2 I ( I I I _._._..............._,_._._._............---.,.._.............._._....,..............._._._._..... -............- _...._... - ._.......... 5 ........_._._._._. ... ....- .......t.._._._._._...... r ! 0 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Elevation of Springbrook Creek(NGVD) Sverdrup Corporation Figure 20 4/6/92 SD_TABLE.XLS Existing Site Outflow Under Existing Storage Conditions Storm Inflow Outflow %Change Elevation Total Volume Detained Total Storm Volume Fraction Detained Event (cfs) (cfs) Out/In (NGVD) ( ) ;(co M Water Quality 2.70 2.60 96% 9.06 1,742 97,900 2% 2-Year 24-Hour 27.98 22.49 80% 10.59 30,492 681,797 4% 5-Year 24-Hour 37.52 27.36 73% 10.88 54,014 896,041 6% 10-Year 24-Hour 48.69 31.41 65% 11.12 84,071 1,161,633 7% 25-Year 24-Hour 56.47 35.05 62% 11.34 118,919 1,441,900 8% 50-Year24-Hour 57.06 35.41 62% 11.36 122,404 1,469,134 8% 1 00-Year 24-Hour 65.08 37.26 57% 11.54 157,687 1,726,400 9% 100-Year 7-Day 45.65 36.21 79% 11.42 134,165 4,730,311 3% Post-Development Outflow Under Proposed Storage Conditions Storm inflow Outflow %Change Elevation Total Volume'Detained Total Storm Volume Fraction Detained Event (cfs) (cfs) Dut In (NGVD) (cf) cf 96 Water Quality 5.03 1.60 32% 8.65 36,155 117,276 31% 2-Year 24-Hour 35.96 11.55 32% 9.15 199,940 718,116 28% 5-Year 24-Hour 47.20 14.72 31% 9.33 270,943 935,209 29% 10-Year 24-Hour 60.77 16.04 26% 9.64 398,138 1,201,180 33% 25-Year 24-Hour 70.58 18.84 27% 9.94 533,610 1,480,545 36% 50-Year24-Hour 71.62 19.23 27% 9.97 548,856 1,511,537 36% 1 00-Year 24-Hour 81.20 22.36 28% 10.22 670,824 1,778,975 38% 100-Year 7-Day 48.16 21.26 44% 10.13 628,571 4,823,624 13% Sverdrup Corporation Figure 21 4/6/92 SD_TABL2.XLS Comparison of Existing Versus Post-Development Conditions Storm Pre-Dev Post-Dev Change Volume Pre-Dev;> Post-Dev Pre-Dev Closed Post-Dev Closed Closed Depression Event Outflow Outflow Post/Pre Increase Max Elevation Max Elevation Depression Depression Differential Ms) (cfs) (%) (co (NGVD) (NGVD) (NGVD) NGVD), (feet Water Quality 2.60 1.60 62% 19,376 9.06 8.65 11.15 8.91 -2.24 2-Year 24-Hour 22.49 11.55 51% 36,319 10.59 9.15 12.80 10.29 -2.51 5-Year24-Hour 27.36 14.72 54% 39,168 10.88 9.33 13.19 10.70 -2.49 10-Year 24-Hour 31.41 16.04 51% 39,547 11.12 9.64 13.61 11.17 -2.44 25-Year 24-Hour 35.05 18.84 54% 38,645 11.34 9.94 14.05 11.62 -2.43 50-Year 24-Hour 35.41 19.23 54% 42,403 11.36 9.97 14.08 11.67 -2.41 100-Year 24-Hour 37.26 22.36 60% 52,575 11.54 10.22 14.43 12.08 -2.35 100-Year 7-Day 36.21 21.26 59% 93,313 11.42 10.13 15.24(1) 15.20(2) -0.04 Notes: 1. Outflow of 9.98 cis occurs above elevation 15.00 over the existing NE Meadow Sill. 2. Outflow of 42.88 cfs can occur above elevation 15.00 over the proposed Floodplain Sill. Sverdrup Corporation Figure 22 4/6/92 DISHEVNT.XLC Discharge vs Recurrence Event for Pre-and Post-Development 45.00 --------------- ....... ........ .............'F -_J '*" ................................................................................. .............................................................................................................. ............................. 1 1 T,-1 • Post-Development 40.00 ----------------------- .................... . ............. ................................................................................................... ............... ......... .... 0 Pre-Development 35.00 ................................................... .. ..... ... ................................... .......... .............................................................. .......................................... 30.00 ............................................................................................. ......................................................................................................... ...... .... ............. 1 00-Yc ar 7-Day 25.00 -- -------------------------- -------------------...................................... ... ...................... ......................................... ................. Event as.Msed Do pressic n'I 20.00 ----------------------------- .. ................................................... .................................................................................... ..... ........ ............................ ... ................... .............................................. ..... .... o 15.00 ---------------------------- ............. ...........- ..... . . ....... .................... ......... ......... ............. . .......... .............................. .................. ........... .................... ....... 10.00 ..Y.Val ar'Quality.Ever t.................... ................. ................ ...... .......... 5.00 -- -------------- .... ....................................................... ....... - .............. ......................................... ............... ......... .... ......... . ..... ... 0.*00 1 2 5 10 25 50 100 1000 Recurrence Interval for 24-Hour Storms (years) Sverdrup Corporation Figure 23 4/6/92 OUTSTAGE.XLC Outflow vs Stage for Pre-and Post-Development Site 45 ..... ..._.,....................................._.._........................_...._.............................................-------------......----------.....................................;................._.................. . _...._...._......-.... --._._..............._... - ............................. ; ; i 40 --............ ■ Post-Development ...__....._.......................-..............................._............... _ _ I 35 Pre-Development ............................ ._........................ ..................... ti ........................ I ......................... 0 .............. ...... ....... ; : i I I 30 i ; ; i ; ............. i: : a O 3 i i ' 1 5CD 20 ............. ._._......... .--_..._.........._._._. ._..................._..........1 ..._._ ........._.....--......................_.........:..Outflow above stage 11 is governed.._........................_...i........................._...... o by backwater considerations i 15 : *This graph represents outflow for the i 10 - ._...._....._._....a................................................._ ............................ _ ............................- ._..............._......... _._._.culvert only.. For overflow con ......_ ; �.. ,... i i ` see Fjgure 26 i 5 ; --------------------------- -............................ .............................. ............................. .............................. ............................ : ; ; : i i U 6 7 S 9 10 11 12 13 14 15 16 17 Stage(NGVD) Sverdrup Corporation Figure 24 4/6/92 STAGSTOR.XLC Stage vs Storage Curves for Pre- and Post-Development ... 17 ....................._._.;._..............._...._........j........................................................... ........................... ..............---........... ......-....... -----: ..-----------..._._._ ._....---------- ..._........................ ..........................._ ------------- _ j 16 ................................._...._.......i..................................... ...................................... ...........i-----. _........................._..............._.................. ........ .......................... ..._................... -.............................. ....... i .E.... i .............................i.................................a.................._.............i............................ '............................ .............................4..........................._. .......................... ............. .......................... .... ......_........ i 15 t j i i i 3 � 14 ._............... ........_..._ ........................ ....._................... .... ............ ......_._............... ........ ,.......... ... ,.... i... I I i , i ' I 13 , ................_........................ ..... ....:................................ ............ - ..... .......................... , , i I 12 -------------- -_....�._...................... ....... 1.... ....... ._...................4........._................... ..................................j.................................1....._.................._._._l.._................._..........j.................._.............I-.................................j....................._...........�............................... .j QJ i i i 1 � , E Q� i 0 11 t ............_._._........}......... _ ................................ {.._...........................{..........._._...._..........- --._._..------------...._._i ,.........._......................r..._._...._...................;...._............_._._._.....j............_...._............ .,.. _.. ... _... cn t.. i 10 ..........................._.... ......_....................................................._._................... --------------.._.----------- .......................... ............................................. ' Post-Development Pre-Development 9 ....................................._.................----.-----..._---------......--..................................................... ............................ Pre-Development Flood Storage 8 ....................._....i........._......._._._._....;....................._..........i..._._._......................{.............................. ......................... ........................................... — i t t 7 ' ..... ............................_.....................................-----..........._............. ................__......................._...._....._..... ....._.....__...._...... 6 0 10 20 30 40 50 60 70 80 90 100 110 120 Storage (acre-feet) Sverdrup Corporation Figure 25 4/6/92 OUTSTAG2.XLC Capacity of Pro- and Post-Development Flood Sills vs Stage 900 ........................... ..............................-.................... ..........................................................................T..................................................................................... ....................................................................................T ........... 800 .........._._I-............................................................................................. ............................................................................... .................................................. .............. ............. 700 ................... Post-Development 4........................................................ ..........................-------------- ........................... ............T------ T* 0 Pre-Development 600 t..............t-1-1111-1-11 .............. t----------- ........... ........... .. ...................................... .......... .............4.............I......................t........................................................ 500 ............t............t....... i.......................... .............. 1............t---------- .......T t�........................... 2�1 400 -----------F___ ....................................... ............... .1.................................... ............................................................................ ............... ..........................I I......................... ............. 300 -.4....... j.................................... ............ .......... ......... ............... ......................... ........... ................ ............. t...........t ....................... t • 200 .................................................................... ......................... . ..... ...........1-----------i 4..............1------------ .......................... ................................... ............. 100 -----------.............. ............. ......... ............... ............ ............. ............. .......... ............ ..................... 0 0 14 14.5 15 15.5 16 16.5 Stage (NGVD) Sverdrup Corporation Figure 26 4/6/92 Longacres Park On-Site Water Quality Monitoring Laboratory Analysis and held Testing Report Springbrook Creek March 31, 1992 Field Data Lab Analysis Stage Gage Air Temp Water C.Cond. Date Time Reading* (°C) Temp(°C) pH DO(mg/1) (umhos/cm) TOC(mg/1) TSS(mg/1) Comments 06/18/91 N/A N/A 18 15.0 6.97 2.80 350 8.5 10 06/24/91 16:00 3.86 29 17.9 7.10 2.68 335 7.5 13 07/01/91 11:15 3.85 24 19.0 7.16 2.28 374 8.2 18 07/08/91 11:10 3.77 24 16.5 7.49 3.59 319 6.5 13 07/15/91 10:00 3.79 15 16.2 6.63 3.52 364 5.4 14 07/23/91 11:05 3.77 22 16.9 7.26 2.97 343 7.4 15 07/29/91 15:00 3.76 25 20.1 7.26 3.25 389 7.9 11 08/05/91 14:10 3.71 24 19.3 7.00 1.68 404 8.5 12 08/12/91 14:30 3.81 26 19.7 7.25 4.26 61 13.0 11 08/19/91 10:00 3.81 23 18.2 7.45 2.70 57 7.8 12 08/26/91 10:35 3.87 17 14.5 7.14 4.25 271 7.2 7 09/02/91 10:30 3.81 22 18.2 7.32 5.42 212 7.2 7 09/10/91 13:30 3.91 23 15.6 7.14 5.48 290 5.3 8 09/16/91 10:20 4.06 23 13.4 7.19 4.90 322 6.5 9 09/23/91 11:30 4.51 22 14.6 7.16 5.44 3 5.2 4 Suspect C.Cond. 09/30/91 10:00 4.56 20 17.8 6.28 5.20 345 4.7 9 10/07/91 10:20 4.55 15 12.7 7.02 5.76 316 3.7 8 37 days no rain 10/15/91 08:40 4.51 13 11.1 6.93 5.05 344 4.6 8 10/21/91 17:20 4.41 10 12.5 7.06 4.42 347 5.8 6 10/28/91 10:30 4.32 7 8.4 7.25 4.21 272 6.2 11 11/04/91 13:25 4.96 7 8.9 6.99 6.98 159 5.4 18 11/11/91 13:15 5.31 12 11.9 6.68 8.40 129 6.3 42 first flush rain 11/18/91 10:30 4.81 7 9.4 6.69 6.75 156 15.0 9 11/25/91 12:30 4.71 8 10.5 7.20 6.51 134 5.1 14 12/02/91 10:40 3.96 6 8.3 7.18 5.14 287 10.0 15 12/09/91 10:25 4.62 10 8.8 6.75 7.56 139 5.8 28 12/16/91 10:05 3.92 0 4.9 7.07 4.84 307 9.0 19 12/22/91 10:00 4.13 5 7.0 7.10 6.52 230 6.0 8 12/30/91 11:45 4.36 10 8.7 7.12 6.75 272 5.6 17 01/06/92 N/A 4.07 N/A 5.8 7.39 7.51 287 6.7 10 01/14/92 11:40 3.89 7 7.7 7.65 5.14 335 7.9 10 01/20/92 10:20 3.96 4 5.0 7.29 5.91 315 7.0 23 01/27/92 12:00 5.41 9 8.1 7.01 6.98 177 6.7 35 02/02/92 14:30 6.59 10 8.3 6.75 7.32 139 7.5 50 02/10/92 12:00 4.26 9 8.9 6.80 6.00 300 7.9 13 DO do Cond from lab 02/17/92 09:30 4.19 6 8.0 7.24 9.09 346 78.0 19 02/24/92 11:05 4.55 8 9.2 7.41 6.24 176 7.4 8 03/02/92 11:40 4.09 10 9.8 7.51 N/A 327 7.1 18 bad DO reading 03/09/92 12:25 4.01 13 10.3 8.01 5.18 332 6.9 13 03/16/92 10:30 4.25 10 9.6 6.79 6.18 234 • Springbrook Creek water surface elevation a Stage Gage Reading + 0.71 feet FIGURE 27 i li i i i i i fi fi i i fi fi i i i i i fi Longaeres Park On-Site Water Quality Monitoring Laboratory Analysis and Field Testing Report Site #3 March 31, 1992 Field Data Lab Analysis k Samples Stage Gage Air Temp Water Temp C. Cond. Composited Date Time Reading (°C) (°C) pH DO(mg/1) (umhos/cm) TOC(mg/1) TSS(mg/1) Comments 1 06/18/91 10:50 N/A 18 15.9 6.94 0.55 613 20.0 240 init.baseline,no rain 06/24/91 N/A N/A N/A N/A N/A N/A N/A 07/01/91 11:50 N/A 24 20.3 7.31 0.58 542 07/08/91 10:45 N/A 24 17.6 7.62 1.33 448 07/15/91 10:45 6.33 15 16.9 7.04 0.83 467 07/23/91 11:05 6.29 22 18.4 7.23 1.60 468 30.0 1300 Very high TSS I 07/29/91 15:20 6.25 25 21.8 7.62 3.13 456 08/05/91 14:30 6.25 24 21.2 7.49 0.87 522 1 08/12/91 14:50 6.25 28 20.4 7.70 1.97 74 30.0 32 08/19/91 10:25 6.21 24 19.5 7.74 1.69 70 08/26/91 11:05 6.29 17 15.0 7.38 1.53 326 29.0 100 09/02/91 11:15 6.29 22 18.5 7.89 1.40 332 18.0 84 09/10/91 14:05 6.33 23 16.2 7.64 0.82 489 09/16/91 11:10 6.42 23 13.5 7.30 1.36 327 09/23/91 12:10 6.33 22 14.0 7.23 0.08 13 Suspect C. Cond. 09/30/91 12:45 6 20 18.8 6.43 3.00 392 10/07/91 N/A 6.00 15 10.9 7.45 3.23 358 37 days no rain 10/15/91 09:30 5.92 IS 18.4 7.21 2.91 397 1 10/21/91 16:30 5.67 10 11.8 6.91 4.12 342 24.0 20 2 10/28/91 11:15 5.67 7 6.6 7.14 1.08 268 20.0 40 11/04/91 12:50 6.58 7 9.3 6.82 7.05 195 4 11/11/91 13:55 7.10 12 12.8 7.01 10.06 98 10.0 110 first flush rain 11/18/91 11:10 6.42 7 8.7 7.12 6.51 171 11.0 230 2 11/25/91 13:00 6.42 8 10.2 7.21 5.57 185 11.0 95 2 12/02/91 11:25 6.42 6 7.3 7.27 2.77 312 9.6 68 Heavy sedimentation 9 12/09/91 11:10 6.85 10 8.6 7.27 8.61 149 12.0 50 12/16/91 11:00 6.42 0 4.4 7.15 1.62 565 21.0 110 12/22/91 11:00 6.50 5 6.9 7.11 3.85 542 23.0 60 12/30/91 12:30 6.50 10 7.8 7.58 8.79 211 7.4 150 01/06/92 N/A 6.42 N/A 5.3 7.64 4.68 649 01/14/92 12:20 6.42 7 8.3 7.49 2.80 552 01/20/92 10:50 6.42 4 4.1 7.61 3.35 556 2 01/27/92 12:40 7.20 9 8.1 7.42 8.53 108 18.0 120 2 02/02/92 15:15 7.04 10 8.6 6.80 7.99 173 25.0 3600 very high TSS 4 02/10/92 12:30 6.67 9 9.8 7.00 1.50 930 26.0 41 DO&Cond from lab 02/17/92 10:15 6.60 6 8.3 7.17 4.20 779 4 02/24/92 11:50 6.68 8 9.9 7.32 4.5E 392 28.0 200 03/02/92 12:20 6.50 10 11.5 7.31 N/A 673 Bad DO reading 03/09/92 13:10 6.50 13 11.4 7.70 2.0E 650 4 03/16/92 11:15 6.30 10 9.7 7.27 3.52 463 Lab analyses N/A FIGURE 28 111111� 11111� 111111� 1� 111111� Illll� 11111� to Vo tft ima too ino im Longacres Park On-Site Water Quality Monitoring Laboratory Analysis North Infield Creek At Abandoned Pumphouse March 31, 1992 Date Time TOC(mg/1) TSS(mg/1) I Comments 09/ 0/91 N/A 36.0 91 Very low flow 11/04/91 12:30 13.0 49 11/11/91 14:50 13.0 120 first flush rain 11/19/91 11:40 8.0 73 Longacres Park On-Site Water Quality Monitoring Laboratory Analysis South Marsh Outlet (Site #6) Date Time TOC(mg/1) TSS(mg/1) I Comments 11/11/91 08:30 14.0 9 first flush rain 11/18/91 12:15 14.0 15 11/25/91 17:00 20 4 FIGURE 29 MI M 'MI 'MI wo 1w Im Longacres Park On-Site Water Quality Monitoring Storm Event Monitoring Laboratory and held Testing Report March 31, 1992 Field Data Air Temp Water Temp C. Cond. Site Date Time Gage Elev. (°C) (°C) pH DO(mg/1) (umhos/cm) Comments Springbrook 12/05/91 14:50 6.10 9 9.7 7.35 8.9 124 Storm event 1 North Infield Creek 12/05/91 15:40 - 9 10.1 7.06 9.8 47 Storm event 1 South Marsh Inlet 12/05/91 16:25 12.03 9 9.1 6.44 6.3 44 Storm event I (Site k7) Springbrook 01/29/92 12:40 6.65 10 10.0 6.90 8.7 84 Storm event 2 North Infield Creek 01/29/92 13:10 - 10 10.0 6.60 9.6 71 Storm event 2 South Marsh Inlet 01/29/92 13:30 12.09 10 10.5 6.60 5.1 85 Storm event 2 (Site V) Lab Analysis Biochemical Chemical Nitrate T-Org Total Total Oil Total Total Total Oxygen Oxygen +Nitrite Halogens Kjeldahl &Grease Organic Phosphate Suspended Demand Demand as N (SW 9020) Nitrogen (413.1) Carbon as P Solids Site Date Time (mg/I) (mg/1) (mg/I) (mg/1) N(mg/1) (mg/1) (mg/1) (mg/1) (mg/1) Comments Springbrook 12/05/91 14:50 10 12 0.15 0.02 0.53 5 5.6 0.33 87 Storm event North Infield Creek 12/05/91 15:40 10 20 0.22 0.11 0.65 5 12 0.38 92 Storm event South Marsh Inlet 12/05/91 16:25 10 16 0.03 0.02 0.50 5 11 0.17 4 Storm event I (Site X7) Springbrook 01/29/92 13:10 10 24 0.78 0.02 0.66 9 4.8 0.18 67 Storm event North Infield Creek 01/29/92 12:40 10 31 0.31 0.02 0.88 5 7.7 0.26 100 Storm event 2 South Marsh Inlet 01/29/92 13:45 10 34 0.11 0.02 0.71 8 8.8 0.16 3 Storm event 2 (Site V) FIGURE 30 Richard R. Horner, Ph.a Environmental Engineering and Science i 230 N.W. 55th Street Seattle, Washington 98107 ' (206) 782-7401 February 29 , 1992 ' Mr. J. David Benson Sverdrup Corporation 3300 Carillon Point ' P. 0. Box 97062 Kirkland, WA 98083-9762 Dear Dave: This letter provides my evaluation of a portion of the stormwater management system proposed for the Boeing Longacres ' site. I have performed the evaluation as requested by Randall Parsons of the City of Renton; i. e. , by comparing the estimated water quality improvement performance of the proposed system and ' the system required by the Renton code. This letter covers my analysis and findings for Catchment C (including the occasional drainage from Catchment A that will enter the Catchment C ' system) . I will provide similar evaluations after you finish your proposed designs for the Catchment B and SW 16th systems. METHODS ' I estimated the stormwater treatment performance of wet ponds using the methods developed by Driscoll (1983) from data ' collected on numerous such systems during the U. S. Environmental Protection Agency's Nationwide Urban Runoff Program (NURP) . These methods relate long-term effectiveness (the average over numerous runoff events) to the "volume ratio" (pond dead storage volume to mean storm runoff volume) . The latter term is calculated from mean precipitation quantity, a regional climatological statistic. This ratio has been found to govern ' the capture of pollutants during the quiescent period between runoff events. ' The NURP methods also recommend pond surface area in relation to contributing catchment area (the "area ratio") and overflow rate for good performance. The larger the surface area ' is in relation to the watershed, the better is the operation of Pollutant removal mechanisms relying on light and interaction with the atmosphere. Minimizing overflow rate improves short- term removals of the larger solids during and immediately after FIGURE 31 ' Mr. J. David Benson February 29, 1992 Page 2 ' storms, when the live storage zone of the pond is filled. The i recommended maximum overflow rate is 10 cm/hour. I combined the volumes and surface areas provided by second- and third-stage ponds for the analysis. Initially, I took no t account of wet vaults, because their overall water quality benefits are very limited as a result of short residence time and excluding light and atmospheric interactions. It should be noted, however, that vaults are useful to increase water storage ' for release rate control, as presettling chambers to catch the largest particles, as oil/water separators when fitted with appropriate baffling and skimming equipment, and as potential ' locations for advanced oil/water separators should they ever be needed. I regarded the outlet channel, which is to be at least ' partially vegetated, as a biofilter and evaluated its performance by using results from the Washington State Highway Runoff Water Quality project (Mar et al. 1982 ; Horner and Mar 1982; Horner ' 1988) . Approximations were required because of current uncertainty concerning the final configuration of the channel. I reasoned that it should be at least equivalent in performance to the designs recommended by the references cited and required by the Renton code based on the King County Surface Water Design Manual (King County Surface Water Management Division 1990) . The basis for my reasoning is that the channel will have greater size, and therefore water residence time, than biofilters designed strictly according to the requirements, although some of the cross section may not be vegetated. I recommend that the design include native hydrophytic vegetation over the full width and length of the channel for the maximum water quality benefits. ' I analyzed performance in terms of the expected removal efficiencies for the following pollutants: total suspended solids (TSS) ; total phosphorus (TP) ; and the metals lead (Pb) , copper (Cu) , and zinc (Zn) . The ?BURP data suggest that removals ' of total Kjeldahl nitrogen (TKN) and chemical oxygen demand (COD) in a wet pond are similar to those of Cu and Zn, but no basis exists to evaluate trapping of those pollutants in a biofilter. ' TP removal by biofiltration is seasonally variable because of the annual cycling of vegetation through a growth period, when nutrient uptake occurs, and a death and decay phase, when stored nutrients are released. Although these losses through release ' could partially be avoided by a fall harvesting program, it is most prudent to consider biofiltration to provide no net TP capture over a full annual period for the current analysis. tThe applicable Renton code requirements and the proposed design for Catchment C involve a wet pond and biofilter in 1 series. Data are available in the references cited earlier to estimate the performance of the two elements in the sequence separately. It is reasonable to assume that in a series arrangement, however, the second device in line will not perform ' Mr. J. David Benson February 29, 1992 Page 3 ' at the same level as if it were alone, because the pollutants that are easiest to remove will have already been captured. The ' available research provides no basis to establish the loss in efficiency of the second element. To compare on the same basis a treatment system required by the code with the system proposed, the analysis assumed two "penalty" levels for the second device: ' 25 and 50 percent. Therefore, the overall efficiency of the series (Es, as a fraction) was estimated as: ' Es = 1 - (1 - El) (1 - xE2) ; where E1 = efficiency of element 1 (as a fraction) , E2 = ' efficiency of element 2 (as a fraction) , and x = the efficiency remaining after imposition of the "penalty" (0. 75 or 0. 50) . Efficiency as a percentage is 100 times the fractional efficiency. ANALYSIS OF CATCHMENT C ' Code Requirements From the water quality standpoint, the characteristics of ' Catchment C make it subject to Core Requirement #1 and Special Requirements #5 and #6 in the King County Surface Water Design Manual. Core Requirement #1 mandates peak runoff late control, plus biofiltration as a result of having > 5000 ft of impervious area subject to vehicle use. Special Requirement #5 specifies a wet pond for treatment based on > 1 acre of impervious area subject to vehicle use and discharge to a Type 1 or 2 stream ' within 1 mile. The requirement further stipulates that the pond surface area be no less than 1 percent of the contributing - impervious area and have a volume that is at least equal to the mean annual runoff volume (i. e. , the volume ratio should be at least 1) . Special Requirement #6 mandates a coalescing plate oil/water separator because of the anticipated > 2500 vehicle trips per day. Therefore, the code requires a biofilter and a wet pond (in either order) and a coalescing plate oil/water separator. I ' based the estimated treatment efficiencies for the wet pond according to the minimum code requirement (a volume ratio of 1) . The efficiencies differ somewhat depending on which element is assumed to be first and the efficiency penalty assumed for the ' second element. I calculated them for both sequences and for penalty assumptions of 25 and 50 percent and estimate them to be in the following ranges: ' TSS and Pb--67 - 87% TP--32% Cu and Zn--48 - 68% Coalescing plate oil/water separators are meant for industrial applications where influent oil concentrations are consistently larger than generally found in urban runoff. They ' Mr. J. David Benson February 29 , 1992 Page 4 ' are capable of reducing oil and grease concentration to 15 mg/L (Horner and Wonacott 1985) . General urban and even highway ' runoff usually contains lower concentrations than this performance limit. A small amount of data (Horner 1988) indicate that biofilters can reduce the usual runoff concentrations to a ' much lower level (< 5 mg/L) . Therefore, a coalescing plate separator would serve mainly as a pretreatment device and a trap for accidental spills in a system also containing a biofilter. Proposed System The stormwater system proposed for Catchment C consists of four wet vaults, two second-stage ponds, a third-stage pond (the large lake) , and an outlet channel. The two stages of ponds will provide a very large capacity and long water residence time to ' treat entering stormwater. Based on the volume ratio represented by the second- and third-stage ponds (24. 7) and the two assumptions for the efficiency penalty for the outlet biofiltration channel, I estimate that the following treatment efficiencies, substantially higher than expected for a system meeting minimum code requirements, can be attained if the system is installed as designed and maintained in the same condition ' during operation: TSS--99% TP--61% Pb--95 - 96% Cu and Zn--65 - 73% ' Additional comparisons with the system required by the code involve the area ratio and overflow rate. While the minimum ' requirement for pond surface area is 1 percent of the contributing impervious area, the proposed pond system will occupy an area equal to 21. 2 percent of the Catchment C ' impervious area and 8 . 8 percent of the total 76. 36 acres in the current project. Overflow rates for the proposed system will be only about one-tenth of those that would occur in a system designed according to minimum code requirements. Even within the period of maximum overflow during storms, the proposed system will have rates below the NURP recommendation most of the time. Only with storms greater than about the 2-year, 24-hour event will the short-term overflow rate exceed that recommendation. In contrast, the minimum system would have rates above that level during most storms. ' The analysis described is based on the runoff contributions expected from Catchment C itself. On occasion drainage will also enter the third-stage Catchment C pond from Catchment A. At a maximum rate of 18 cfs, this contribution will not even begin until an event sized somewhere between the 50- and 100-year, 24- hour level. With the very large capacity of the proposed system ' and the relative rarity of this extra flow, I do not .consider it to detract significantly from the expected performance of the system. ' Mr. J. David Benson February 29 , 1992 Page 5 Your design proposes eliminating the coalescing plate oil/water separators required by the code. I believe that there ' will be no loss of protection from oil pollution for the following reasons. The proposed system does include T-section separators in catch basins and baffling in wet vaults for oil separation. These devices will serve as protection against accidental spills and pretreatment ahead of the wet pond/biofilter system in much the same way as coalescing plate separators would. In either situation most of the oil captured ' from routine runoff would occur in the biofilter. While a coalescing plate separator is more effective than the proposed devices, its capabilities are rarely needed at this type of site. The huge capacity of the pond system will provide further buffering of the receiving water from the effects of oil releases. ' I will provide my assessments of Catchment B and SW 16th by letter as soon as I receive your proposed designs. I will also forward the list of references cited in both letters at that ' time. Meanwhile, do not hesitate to call if you need anything additional. ' Sincerely, ' Richard R. Horner Richard R. Horner, Ph.D. r = ;, ` ' Environmental Engineering and Science - 230 N.W. 55th Street Seattle, Washington 98107 ' (206)782-7401 March 12, 1992 ' Mr. Ronald Bard Sverdrup Corporation ' 3300 Carillon Point P. O. Box 97062 Kirkland, WA 98083-9762 ' Dear Mr. Bard: This letter provides my evaluation of a portion of the ' stormwater management system proposed for the Boeing Longacres site. It covers my analysis and findings for the SW 16th Street catchment and Basin B. Comments about the two systems follow some general remarks about the analysis. General ' You proposed biofiltration swales in both catchments for storm runoff water quality improvement. I evaluated your proposed designs using the results of the Washington State ' Highway Runoff Water Quality Project (Mar et al. 1982; Horner and Mar 1982 ; Horner 1988) , as well as some information from a current study that is not published yet. This analysis differs from the King County Surface Water Design manual by using a lower Manning's n value and the actual slope, instead of a slope of 2 percent in all cases. I have no experience, nor have I ever seen anything in the literature, to justify a value of n anywhere near ' King County's designated 0. 35 value. While I expressed that viewpoint to King County before publication of the manual, I was unable to prevail. ' The best indication we have at present is that n is in the vicinity of 0.2 for a biofiltration application in which vegetation height exceeds flow depth. However, measurements have not been made on all of the types of plants that may be used in such applications, nor on a full range of flow depths relative to plant heights. We have to assume some variability with these factors and cover that variability in our design calculations. You did so in your work, and I did the same in my evaluation. ' FIGURE 32 Mr. Ronald Bard March 12 , 1992 ' Page 2 You asked for the rationale for using a 2 percent slope. For a definitive answer you would have to ask Randall Parsons or ' his successor at King County. I do not believe in the philosophy of design that such seeming arbitrariness represents, and therefore cannot justify it. What I recall from the discussions before the manual was published is that the rule was made to introduce conservatism in the design if the slope exceeds 2 percent, in which case the Manning equation would yield a smaller width than if 2 percent were used. Of course, that reasoning does not apply in a situation, such as you have, where the site slope is under 2 percent. ' The fact is that when I investigated the effects of these various considerations in the SW 16th and B catchment swales, there was no radical effect on the conclusions: all reasonable ' combinations yielded design flow velocities well below 1. 5 ft/second, the upper limit adopted in the procedure (Horner 1988) . Also, sizes appear to fit within the available space regardless of the assumptions. ' You also asked for documentation supporting increasing swale length to allow greater depth. We may have a misunderstanding on ' that point. I have maintained that water residence time is the critical variable, and that length and cross-sectional area can be mutually adjusted to achieve the residence time provided by ' 200 ft of hydraulically sufficient ditch, so long as other limits (e. g. , maximum velocity) are held. Therefore, greater length can compensate for inadequate width or depth or both, not for greater depth. I see the limit on depth to be imposed by the height at which the plants would bend because of their own weight and be submerged. That is a particular consideration when contemplating deep flows through grass, but a lesser one with Y_ wetland plants. I see no problem with approximately 8-inch or even somewhat greater depths in wetland systems. SW 16th Street Catchment This catchment is technically subject to King County Core Requirement #1 (peak runoff rate control and biofiltration) and ' Special Requirement #5 (wet pond, unless a below ground structure must be substituted because of space limitations) . I am not performing any evaluation of rate control measures and thus will ' not comment on your quantity calculations. Your proposal is to eliminate detention because of minimal post-development peak rate increase, unless needed for water quality purposes. In that case you would provide detention in a storage pipe. You further ' propose a 400-ft biofiltration swale in lieu of wet pond or other detention, although you reason that a 200-ft swale is adequate according to biofiltration standards. ' I agree that the lengthened swale would offer more water quality advantages than a 200-ft swale and a detention pipe. The ' relatively short residence time and absence of light in enclosed Mr. Ronald Bard March 12 , 1992 ' Page 3 detention systems such as you considered provide little opportunity for pollutant removal mechanisms to work. It appears that space greatly limits wet pond opportunities here, and thus a pond is not a real possibility. To serve well for runoff treatment, a pond must offer sufficient surface area and volume, as I pointed out in my letter of February 29 to Dave Benson. Only if the needed area and volume could be provided would the pond offer a significant advantage over an enlarged biofilter. ' My check calculations on the basis outlined earlier confirm the adequacy of the proposed biofilter. I do not expect velocity to go above 0. 4 ft/second nor flow depth above about 9 inches at ' biofiltration design conditions. I also investigated the channel's capacity when conveying the 100-year, 24-hour storm and found that it is more than adequate. I want to add that the best ' practice is to bypass large flows around the biofilter, in order to avoid resuspension of captured solids and damage to the vegetation. I recommend your consideration of such a bypass. Catchment B My conclusions on the swale sizing are similar to those stated above, although I did get slightly greater widths for 8- inch depth and the basis outlined earlier than you did (4 . 6 ft bottom width and 7 . 3 ft top width for trapezoidal and 6 ft width ' for rectangular) . These deviations do not result in great differences in velocity, the ultimate criterion; in none of the cases that you presented would the velocity rise to anywhere near the 1. 5 ft/second limit. I had less detail about the overall channel dimensions than with the SW 16th swale and thus could not check for capacity to convey the 100-year, 24-hour storm. Again, I recommend bypassing runoff from large events, but if that is impossible, you must have adequate depth to convey the flow assuming the friction offered by the standing plants and with a velocity that does not cause erosion (3 ft/second would be a safe limit) . ' References cited here and in my letter of February 29 are enclosed. Feel free to contact me if I can assist further. ' Sincerely, r r - Richard R. Horner ' Enclosure ' REFERENCES Driscoll, E. D. 1983 . Performance of Detention Basins for Control of Urban Runoff Quality. Proc. International Symposium on Urban Hydrology, Hydraulics, and Sediment Control, ' University of Kentucky, Lexington. Horner, R. R. 1988 . Biofiltration Systems for Storm Runoff Water Quality Control. Municipality of Metropolitan Seattle, ' Seattle. Horner, R. R. and B. W. Mar. 1982 . Guide for Water Quality ' Impact Assessment of Highway Operations and Maintenance. Washington State Department of Transportation, Olympia. Horner, R. R. and S. R. Wonacott. 1985. Performance Evaluation of a Detention Basin and Coalescing Plate Oil Separator for Treating Urban Stormwater Runoff. Environmental Engineering and Science Program, University of Washington, Seattle. King County Surface Water Management Division. 1990. Surface Water Design Manual. King County Department of Public Works, ' Seattle. Mar, B. W. , R. R. Horner, J. F. Ferguson, D. E. Spyridakis, and ' E. B. Welch. 1982 . Summary--Washington State Highway Runoff Water Quality Study, 1977-1982 . Washington State Department of Transportation, Olympia. Richard R. Horner, Ph.D. ' Environmental Engineering and Science 230 N.W. 551h Street Seattle, Washington 98107 (206)782-7401 April 1, 1992 ' Mr. Ronald Bard Sverdrup Corporation ' 3300 Carillon Point P. O. Box 97062 Kirkland, WA 98083- 9762 ' Dear Mr. Bard: I have reviewed the 95 percent complete drainage plans for the SW 16th catchment at the Boeing Longacres site, as well as the 60 percent complete design for Basin B. This letter amplifies on the comments in my letter of March 12 concerning those two catchments. This earlier letter described the methods that I used in my analysis. I am in full agreement with your design for the SW 16th ' biofilter. My first letter on the subject stated my belief that the swale sizing and design velocity and flow depth are consistent with guidelines for achieving the treatment potential of the technique. I recommended in that letter that you consider bypassing storms larger than the design event around the swale in order to avoid damage to it and resuspension of captured solids. You have devised a very good solution by providing diversion ' catch basins to direct flow from the design event into the swale and larger discharges to a storm drain pipe. ' Regarding the swale designed for Basin B, I checked both its capacity to serve well in runoff treatment and its ability to convey the 100-year, 24-hour storm. I found that the dimensions ' are more than adequate for the 2-year, 24-hour treatment design storm in both the smaller western segment and the larger eastern portion, which receives additional flow. Both segments are also large enough to transport flow from the large event without risking channel damage. It would be advisable to deepen each portion slightly, however. The King County manual calls for minimum 1-ft freeboard above the maximum depth of flow. I estimated that the smaller western segment would flow about 3 inches deep during the 100-year, 24-hour storm and the larger reach about 1 ft deep. Therefore, the respective segments should ' FIGURE 33 Mr. Ronald Bard April 1, 1992 t Page 2 be at least 15 inches and 2 ft deep overall, instead of 1 ft and 1. 5 ft as -in the present design. ' I hope that this evaluation suffices for now. I would be glad to assist further as the design develops. S 'ncerely, ' Richard R. Horner t