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Report ZTec Engineers, Inc. . Civil ♦ Structural ♦ Surveying 3737 SE 8 Ave. John McL. Middleton, P.E. Portland, OR 97202 Ronald B. Sellards, P.E Chris C. Fischborn, P.L.S. (503) 235 -8795 FAX: (503) 233 -7889 E -mail: john©ztecengineers.com.. TIGARD AUTO DETAILING 11640 SW PACIFIC HWY. TIGARD 97223 STORM WATER MANAGEMENT REPORT APRIL 2012 ..:, 4 ,:1747 '' tP,.\ ilizi , r =a O k C ' 6 TABLE OF CONTENTS VICINITY MAP STORM DRAINAGE REPORT STORM DRAINAGE AREA MAP LIDA SIZING FORM WATER QUALITY VOLUME AND FLOW CALCULATION ZTec Engineers, Inc. • Civil o Structural o Surveying 3737 SE 8 Ave. John McL. Middleton, P.E. Portland, OR 97202 Ronald B. Sellards, P.E Chris C. Fischborn, P.L.S. (503) 235 -8795 FAX: (503) 233 -7889 E -mail: john @ztecengineers.com April 2012 Tigard Auto Detailing Storm Drainage Report The site is located at 11640 SW Pacific Hwy. Tigard, T1S R1W Section 36 De TL 2400. The site area is 0.8 Ac. According to the Washington County Soil Survey the native soil is Aloha, Hydrological. Group C with a soil permeability of 0.2 to 0.6 inches /hour for depth 8" to 60 ". The site slopes down from north to south at about 5% + / -. The northerly portion of the site has an existing commercial building, with associated AC paved parking /driveway areas, which is proposed for a minor modification for Auto Detailing to be housed in the lower portion of the building. The use requires areas on the south side of the building to be paved. Presently this area of the site is a mixture a gravel surface and undeveloped ground with a thin vegetative covering. The new pavement will be used for driveways and parking. The southerly 100' of the site has a • residential /commercial building with associated yards. The southerly portion of the site - is omitted from drainage considerations as that portion of the property is unaffected by the proposed improvements. Most of the existing surface parking /driveway area drains to existing on -site catch basins. These basins are connected to an on -site storm drainage system that also handles storm runoff from Pacific Highway and properties north of the highway right of way. The existing building has a downspout collection system that connects to an underground pipe. It is assumed that this system connects to the existing on -site storm drainage system and a possible connection is identified on the plans. The building roof drainage system needs to be investigated to verify disposal method and location. The attached plan shows the areas of existing and proposed impervious surface. It is proposed to collect the runoff from the new AC pavement and the portion of the existing AC pavement that presently drains to the area of new pavement, total area 8,284 sq. ft. This runoff will be directed by grade and drainage curbs to a trapped catch basin. The outlet from the catch basin will discharge to a new infiltration basin /rain garden sized per the LIDA Handbook published by CWS. An overflow pipe from the facility will be connected to the existing on -site 24" storm sewer. The storm sewer daylights in an open drainage channel on the west side of the Regal Cinema property south of this site. Alternative methods of treating the runoff from the 8,284 sq. ft. area were considered: • Install filter catch basin- A single cartridge Stormwater Management catch basin could provide the treatment for the .36" in 4 hour water quality storm. This was not chosen due to cost, maintenance and no flow reduction from infiltration or evaporation. • Install Extended Detention Basin -This is similar to the infiltration basin chosen but the small outlet orifice required is a constant maintenance problem. The emergency overflow route from the infiltration basin will follow the existing drainage path used on the site, an existing drainage swale toward the SE corner of the property. EX.) 67.)61(3' R II ELLAID iiiii RUdtll t R+t71f t I StM t y -\ / CAL \ \ te• OV�CNHC a 45 AK - ' , 0 .. : ''. .::+, :.-.: ' ' - . :!' : .. '' .1 :'''' i: W 1 IN 2 igrgitISI 1 e::; :. 4 Il• \ t.: : — — "� - , ' : , :, ' :, :: .:: ' i ' ',..- :: — NiiimiggirAMInfv.AgNiNTMIMIW: i 1E1 I ', co \ Aire legs 'a; r . N sTitiqg Pt P& ill - . - r.' ''' :: 1 ' ' ::- 1 .'z'i :- - ' pr:::: :::i.: ').', • ; ':ii:: :: I Alp \ Gil 1:: : ' . ' ' .1 'I : 1 ; ::,-, : 0 • '.''.• ':::::::. - IN i PPS ar �.®� • ,. ,... ..,. ,,,, \ - L E . Vr7� � ••� i ► - MkE1» 1 OJ : li b _, a !\• S 70 t '). _ pgyyp l[ • M 215.95 215.95 e . .. — �I { �v .��� q � �Z \ ° .R I W I IS)Tib ,� ` l a m I 1'4- a. - 8 , i \ „ j . ° :: Mow i ai u aq .r V " :•,A �. •� _ _ -- - _ 1 415 _ i Pc is my 1.14 ,,. -.... . -. ..- ._ i� QA1 A RUM _ -- .. -' - �. _ - - � 97F � _ 1w F/ L-7 Ti 6 t0 e g4 s s tki — 7 -7 61F4 e..4. A i � , b -'7'w , ,7 Al Clean Water Services LIDA Sizing Form Project Title: . 6,419 Av 7 Project L o c a t i o n : ? ? . s . 0 1 C I Contact Name /Title /Company: 6- Phone /e -mail: 5 8 STEP 1: Determine Impervious Area Requiring Treatment Total Site Area (acres): O. Bo AJ Total Existing Impervious Area (sq.ft.): ? . . 8 . i 1 Pi Proposed New Impervious Area (sq.ft.): Impervious Area Requiring Treatment (sq.ft.) rg g t (Refer to Design & Construction Standards Chapter 4 for instructions to calculate this area, which. will be less.than or equal to the new plus existing site impervious area.) STEP 2: Deduct Impervious Area LIDA Credits Porous Pavement (sq. ft.): Green Roof (sq. ft.): ' ._._ _ Other Credits as approved (sq. ft.): i. Total Credits (sq. ft.): Remaining Impervious area (sq. ft.) (Total from Step 1 — Total Credits): S 2,8 9 • STEP 3: Size LIDA Facilities for Remaining Impervious Area IA: Impervious SF, Sizing LIDA facility size area treated Factor (sq.ft.) (IA x SF) (sq.ft.) Infiltration Planters /Rain Garden , 209- 0.06 . c Flow- through Planter 0.06 LIDA Swale 0.06 j Vegetated Filter Strip j 0.06 Total Impervious S � ( "Must equal total from Step 2 or additional LIDA Area treated ( sq.ft.) V r j facilities or Water Quality Facilities must be added.) ll` i.171 C.._ _.1c *ioM!;n i ('IranAV'drr ticn'icc> July. :) :? TRUS JOIST CORPORATION WSERN DIVISION 0 5 319 S.W. WESTGATE E D • PORT OREGON 97221 BUS: A/C 503/292 -0141 • RES: A/C 503/292 -9439 CHUCK SHATTUCK 5-t v 4- nA,. R, v N F< T-1,401%. 'N G--- P4 ✓i . 4 - C- - t - e--- 1 7 - 7 PAVE iv \ V-"r kcz... " a z:<5.47g- ''' (.1 c-i--,-? s N e..z.a.) PIA 01 (3--4- . rc , 4 .../y'C• PAV . . . .. as..� ...S -- r. tea _ , a, F z- Z- j- i- E5. &°' 0. d/ 7 c. F. 5. - 7. CI Gr P m AL-7c7,12-44 ‘v: s 5 • T, I SI $ I' rr• ;F '1 Lr g. G , & r LA . 0vZ ,F +1 L_ -- r-c) . r S `t;_•J <1.77 S 7a42-,"" .1 N A N 0 F og.: 1/Y , Q. V a -. t....V ( ,. .E x) N.ts 'p 4- ! 1 (Cr E° �c> 1 V TA") - T ' c 7 . L.1 v\ \ .1 F La T a : '. , , . 5 Lop N o tiE Y E,Nrfl Of\ `B. O `t o .)Lq,t . Pi . 6. ):7.Ta. `7 ior.' I /v-4/18' a45/Ai 3... L , 9 . S e . 4 4 .. , ... . t _ . Z . - . _ /_/ s ( l..,p'Y" ,2,.4 -.T.' I o A) f 1Q►,S I 1 LA r A S S N ' S 4P Of' 1tm.`?itk \i1 00..3 A 64 JOB NAME: JOB # - LOCATION: _. SHEET OF SALESMAN: BY __ _ DATE: ____ _. -- • JOB /3lN (W P*Pi Cl rI aJ _ .. • ZTec ENGINEERS, INC. SHEET NO. OF 3737 SE 8th Avenue PORTLAND, OREGON 97202 -3761 CALCULATED 131 7---- DATE � Z-- (503) 235 -8795 CHECKED BY DATE SCALE - �-� _ - F- 12_0 Z 5 `r rr) P d e Z 0. /c) flL 5 I YJ 25 y2 S Tva._ L = 3. „l 1/2 (12_, = C -1\ 9? 3 • 1 -71-> , -- . 1 9 9 = v. 5 . c J ` / x o o/ 0.5, cfs, i-J S & S" /Z. o o x • 1:,