The URL can be used to link to this page

Onsite Pipe Capacity Analysis.pdfm Z� LU Cb Own' C"Aen vc fl, � ft c".1 tj I � 1,5 0p CILI U>l IR z ....... .. . "A Lig lzJ 6v AZI 01 L j aq CL m Qk:: CA - cn SO 13; Q- -a to 00 .U) N iJ CS C3 su CS LO Lci o Pp CL U4 C)0 LO ro (r) 01 cl7 Lr7 � LrA CJ C) 0 p Cq tip 7 CD 0 C) _0 0 (D 6 C) 0- (1) co to (D SO m m 0 n C) CfJ C� ED co r - to > 0 -0 C) a) 00 C) -S 1- co (0 m cl 0 d C) 9 U-) " us C'4 r- r- cla co 6 U) cli 0 03 C') C) 0 0 CD C) cn (0 OD d CD LO o co C) U') > C) 0 (D OD co 0 a) Z >ft Lq C! O M CEJ' 0 LO - 7E) tltl (9 .0 LLJ 0) 0 C_- Q) a_ " - * 0 CF) 2 LL In cn 45 cCy a) m E E m 't LO m Z� LU Cb Own' C"Aen vc fl, � ft c".1 tj I � 1,5 0p CILI U>l IR z ....... .. . "A Lig lzJ 6v AZI m m Cb XX NM� m C, NM� lzJ 6v AZI —Q L j aq CL m Qk:: CA - cn SO 13; Q- to 00 .U) N iJ CS C3 su CS LO Lci o Pp CL m &1e16 STORMWATER MANAGEMENT MANUAL FOR THE PUGET SOUND BASIN inlet control conditions, which may be present or anticipated in the system, are not specifically addressed. Each pipe within the system is sized and sloped such that its barrel capacity at normal full flow (computed by Manning's Equation) is equal to or greater than the 25 -Year design flow. The nomograph in Figure III -2.I can be used for an approximate solution of Manning's Equation. For more precise results, or for partial pipe full conditions, solve Manning's Equation directly: V = 1.49 Rua sl2 n or, using the continuity equation, Q = AV where: Q = 1.49 AR2"s"2 n Q = Discharge in cfe V = Velocity in fps A - Area in ft2 n = Manning's roughness coefficient in s-ftt« (see Table III -2.2) R - Hydraulic radius = area/wetted perimeter, in ft. s = Slope of the energy grade line in ft/ft For pipes flowing partially full, the actual velocity may be estimated from the hydraulic properties shown in Figure III -2.1 by calculating QNtt and VfUI1 and using the ratio of Qdesiga/Q�tt to find V and d (depth of flow) . Table III -2.2 provides the recommended Manning's "n" values for preliminary design using the Uniform Flow Analysis Method for pipe systems. (Note, the "n" valves for this method are 15% higher in order to account entrance, exit, junction, and bend head losses.) 111- 2-6 FEBRUARY, 1992 Table III -2.2 Manning's "n" Values for Pipes Analysis Method Type of Pipe Material Backwater Uniform Flow Flow A. Concrete. pipe and CPEP-smooth interior pipe 0.014 0..012 B. AnnularjEorru2afea metarPIFQor Pipe Arch: 1.2-2/3 x corrugat on riveted) a. plain or fully coated 0.028 0.024 `b. paved invert (40% of circumference paved): (1) flow full depth 0.021 0.018 (2) flow 0.8 depth 0.018 0.016 (3) flow 0.6 depth 0.015 0.013 c. treatment 5 0.015 0.013 2.3" x 1" corrugation 0.031 0.027 3.6" x 2" corrugation (field bolted) 0.035 0.030 C. Helical 2-2/3" x 1/2" corrugation and CPEP- single wall 0.028 0.024 D. Spiral rib metal pipe and PVC pipe 0.013 0.011 E. Ductile iron pipe cement lined 0.014 0.012 F. High density polyethylene pipe (butt fused only) 0.009 0.009 111- 2-6 FEBRUARY, 1992 rITTIMMIMMIMBIMMONER JLine 29, 2010 City of Edmonds Attn: Jennifer Lambert. 121 5`t' Ave. ]"forth. Edmonds, WA 98020 ^i , I mcg jwm� ��I�ur i��` NSM �V�iw� tib�� AN 27 20101 6621 faster Slough Rd. Ph: 425-334-99M Snohomish, WA 98290 Fax: 42.5-334-7380 e-mail: don nabreskeC(bcorn cast. net Subject: SCQ Minimum Requirements 2-10 per ECDC 18.30.060.8 Reference. SFR located at 16200 75"' PL. W. Plan Check #: BLD20100339 S Minim ggm Re uuir meat 2: Preservation of Natural Drai ngge stems: Per ECCD 18.30,01 O.AA ` "Natural drainage course" means the location of the channels, swales, and other non -manmade conveyance systerns as defined by the earliest documented topographic contours existing for the subject property, either from maps for photographs, or such other means as appropriate.' No such natural drainage course or courses exists on the site and hence this requirement is not applicable. SCQjgj M l Kg iir enf : Source ControlsofPollution: Household chemicals and lawn & garden products from the single family home have a 'minimum potential for contamination of storm water flaws. The homeowner is expected to read and follow manufactures directions on such products and follow them accordingly. RM 'UVMMMMMn-n7r Runoff Treatment for the pollution generating surface consisting of pavement is provided with the installation of two Type I catch basins catch basins near the north property line of the site. These Type 1 catch basins provide a sump area for collection of sediment prior to release of storm flows to the city conveyance system. This requirement applies only to situations where storm water discharges directly or indirectly through a conveyance system into a wetland. That is not the case with the discharge from this site and therefore this requirement does not apply.. Mike Gold, 7510 162""d St. S,W. Mage I oft SCQ Minimum Requirement 6: WaterQuallill Sensitive Areas: Per this section of code, "Where local governments determine that the minimum requirements do not provide adequate protection of water quality sensitive areas, either on site or within the basin, more stringent controls shall be required to protect water quality." This section does not apply. No such determination has been made by the city of Edmonds. Furthermore, there are no water quality sensitive areas associated with this site development to be protected. SCO Minimum Requirement 7: Off Site Analysis and Mitigation: An analysis of off-site water quality impacts resulting from the project has been addressed in the Direct Discharge Report prepared by this engineer and dated April 5, 2010. The report verifies that the downstream conveyance system has adequate capacity to convey storm drainage flows released from the site. SCQ Minimum Requirement 8: Basin Planning: There is no adopted and implemented watershed -based basin plan. Hence, this minimum requirement does not apply. SCQ Minimum Requirement 9: Operation and Maintenance: The applicable operation and maintenance schedule for proposed catch basins storm water facilities is attached. SCQ Minimum Requirement 10: Financial Liability: Per city review comments dated June 8, 2010 a $50,000 performance bond will be required prior to issuance of the permit. The owner intends to post this bond and thus the requirement will be fulfilled. Sincerely, Donna L. Breske, P.E. Attachment: Operation and Maintenance Schedule for Catch Basin Mike Gold, 7510 162nd St. S. W, Page 2 of 2 No. 5 — Catch Basins 'AAaintenance; „: :Defect 061nditions Who Maintenance.is Needed , Rpsutts Expected When per#ormed General Trash & Trash or debris which is located immediately No Trash or debris located Debris in front of the catch basin opening or is immediately in front of blocking inletting capacity of the basin by catch basin or on grate more than 10%. opening. Trash or debris (in the basin) that exceeds 60 No trash or debris in the percent of the sump depth as measured from catch basin. the bottom of basin to invert of the lowest pipe into or out of the basin, but in no case, less than a minimum of six inches clearance from the debris surface to the invert of the lowest pipe. Trash or debris in any inlet or outlet pipe Inlet and outlet pipes free blocking more than 113 of its height. of trash or debris. Dead animals or vegetation that could No dead animals or generate odors that could cause complaints vegetation present within or dangerous gases (e.g., methane). the catch basin, Sediment Sediment (in the basin) that exceeds 60 No sediment in the catch percent of the sump depth as measured from basin the bottom of basin to invert of the lowest pipe into or out of the basin, but in no case less than a minimum of 6 inches clearance from the sediment surface to the invert of the lowest pipe. Structure Top slab has holes larger than 2 square Top slab is free of holes Damage to inches or cracks wider than 114 inch and cracks. Frame and/or Top Slab (Intent is to make sure no material is running into basin). Frame not sitting flush on top slab, i.e., Frame is sitting flush on separation of more than 314 inch of the frame the riser rings or top slab from the top slab. Frame not securely and firmly attached. attached Fractures or Maintenance person judges that structure is Basin replaced or repaired Cracks in unsound. to design standards. Basin Walls/ Bottom Grout fillet has separated or cracked wider Pipe is regrouted and than 1/2 inch and longer than 1 fool at the secure at basin wall. joint of any inlet/outlet pipe or any evidence of soil particles entering catch basin through cracks. Settlement/ If failure of basin has created a safety, Basin replaced or repaired Misalignment function, or design problem. to design standards. Vegetation Vegetation growing across and blocking more No vegetation blocking than 10% of the basin opening. opening to basin. Vegetation growing in inlettoutlet pipe joints No vegetation or roof that is more than six inches tall and less than growth present, six inches apart. 4-36 Volume V —Runoff Treatment BMPs August 2001 NO No, 5 — Catch Basins Maintenance Dbfect Conditions ons When Mairiteriance i5 Needed Results Expected tNhen, Component::>.. ;`.: Maintenance is -. performed Contamination See "Detention Ponds" (No. 1), No pollution present. and Pollution Catch Basin Cover Not in Cover is missing or only partially in place. Catch basin cover is Cover Place Any open catch basin requires maintenance_ closed Locking Mechanism cannot be opened by one Mechanism opens with Mechanism maintenance person with proper tools_ Bolts proper tools. Not Working into frame have less than 1/2 inch of thread. Cover Difficult . One maintenance person cannot remove lid Cover can be removed by to Remove after applying normal lifting pressure. one maintenance person, (Intent is keep cover from sealing off access to maintenance.) Ladder. Ladder Rungs Ladder is unsafe due to missing rungs, not Ladder meets design Unsafe securely attached to basin wall, standards and allows misalignment, rust, cracks, or sharp edges. maintenance person safe access_ Metal Grates Grate opening Grate with opening wider than 718 inch. Grate opening meets (If Applicable) unsafe design standards. Trash and Trash and debris that is blocking more than Grate free of trash and Debris 20% of grate surface inletting capacity. debris. Damaged or Grate missing or broken member(s) of the Grate is in place and Missing_ grate. meets design standards. No. 6 — Debris. Barriers (e.g., Trash Racks) General Metal August 2001 Trash and Debris Damaged/ Missing Bars. Inlet/Outlet Pipe Trash or debris that is plugging more than 20% of the openings in the barrier. Bars are bent out of shape more than 3 inches. Bars are missing or entire barrier missing. Bars are loose and rust is causing 50% deterioration to any part of barrier. Debris barrier missing or not attached to pipe Barrier cleared to design flow capacity. Bars in place with no bends more than 3/4 inch. Bars in place according to design. Barrier replaced or repaired to design standards. Barrier firmly attached to pipe Volume V —Runoff Treatment BMPs 4-37