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Sewer Tank Discussion with Jon Yanasakhpr ~u uo VG44p vougias rsioom ,sou 4uu ursGts p. i T ~ GD ~a~ni~er CjenerAl ,~eve[opment ~Jnc. P.O. Box 627 Rainier, Washington 9857fi (360}400-Q740 FAX TRA14'SMITTAL DAME: 3't ~ ~ ~ h s ~--...~ CDMP.4,~VY.• ADDRESS.• FROM.• Rainier Generrtl Developrnerit, Inc. FAX #: 360-40D-0828 C01~FTACT.• )~~. J~ Total number ofpages inclztding cover sheet: DEP~:- I, f all pages are not received, please contact sender at 360-40Q-0740. hfESSAG.E: ~, l !'~ Apr :~U U2S U2:44p Douglas tSloom Tah~ma Terra Multi-Family STEP Tanks Subject: Tahoma Terra Multi-Family STEP Tanks From: "Glint Pierpoint" <clint.pierpoint@kpff.com> Date: Tue, 15 Apr 2048 16:39:33 -0740 To: "'RGD"' <rgdinc(u7ywave.com> CC: "'Mark Steepy"' <mark.steepy~.kpffcom> Doug, For your review and discussion... ~~J ~~ ~~ v ~, ~~ ~ ~ f~ Regarding the STEP tank sizing and confrguration for the multi-family structures, we have provided tank sizing calculations that have been accepted by the City of Yelm. The configuration of the tanks that the city has requested could be improved by applying the best available science for treating and conveying sewage. Traditionally, wastewater enters a single chamber tank, allowing solids to settle and scum to float. The settled solids are anaerobically digested reducing the volume of solids. The effluent Then drains to a pump chamber and pumped to the treatment plant. Latest engineering practices divides the septic tanks into two chambers where the liquid flows from the first compartment into the second chamber where further settlement and treatment takes place. The reduced concentration effluent then drains in a relatively clear condition into a pump chamber and pumped to the treatment plant. In addition to prouiding better initial treatment of the wastewater being pumped to the plant, the frequency of required tank pumping is not increased since the sludge and scum accumulation capacity is not reduced. to fact, pumping intervals could be increased due to a higher level of treatment being provided. Attached are excerpfs from DflE's Criteria for Sewage tNorks Design and Penn State -Agricultural and Biologics! Engineering's Septic Tank Pumping further supporting the proposed conlguration. If you have any questions regarding this matter, please don't hesitate to contact me. Cordially, Minton D. Pierpoint I Associate KPFF Consulting Engineers 4200 Sixth Avenue, Suite 309 Lacey, Washington 98503 Q: (360) 292-7230 PA: (360) 790-6832 F: (360) 242-7231 cl inr.pieroointC}k~ff.com www, k~ff. com Content-Type: application/pdf' _04151ti3435_001.pdf Content-Encoding: base6=~ Content-Type: application/pdf _0415163452_001.pdf Content-Encoding: base64 ;~bU-4UU-U828 p.2 I oft 4/16!2003 8:03 t11ti1 Apr 3U Utz U2:44p Douglas t3loom 360-400-0828 p.3 CF-28 December 1998 Criteria far Sewagel{~orksDesign may opt to include design zones within, the system with different maximum hydraulic guidelines_ The pump selected shall also be able to discharge influent peak flow (volume) w;thout exceeding the working volume within the pump holding vessel (see C1-10.1.6). Influent peak flow (volume) will be detemnined by reviewing the number of fixtures within a structure or by applying a peaking factor to average daily volumes. The designer shall use a minimum of 400 percent of average daily flow for estimating peak influent volumes. C1-1©.1.6 TanlJVessel Type and Sizing Any vessel used for construction of a STEP, SDG, or GP system shall conform to general guidelines, as follows: • Vessels shall be consttucted of a material that does not degrade from corrosion caused by the surrounding soil or the wastewater being held in the vessel. Common materials include reinforced cement concrete, reinforced fiberglass, and polyethylene. • Vessels shall be designed to withstand the external soil loading based upon the type of soil, lateral loading due to hydrostatic water pressure, and wheel loading. Vessels to be located iiz atraffic-bearing area shall be designed to withstand HS-20 truck loading with appropriate impact factors. • All vessel designs will bear the stamp of an engineer licensed in the _ State-of 'Vt%aslzingtonwlth specific expertise in-design-of sirnikar . . vessels certifying that the tanks will meet the loading conditions specif ed herein. • The vessel, appurtenances (risers, lids, cleanouts, inspectionpoits, inlet and outlet piping, etc.), and the connection between the vessel and appurtenances shall be watertiDht. Each vessel and,appurtenar-ces once fully assembled and installed shall be tested for leakage by filling with water orlow-pressure air. The test will be witnessed by the agency operating the system or their duly authorized representatives. No vessel will be accepted if there is any noticeable leakage during the testing period. A. Tank Configuration STEP/SDG A vessel (tank) up to 1,500 Gallons in size shall be confieured in accordance with the intent of the International Association of Plumbing and 14fechanical Officials (IA.PMO) SPS 1-87 with the following recommendations: • A baffle wall or compartment wall is recommended~but not required for 1,000- and 1,500=gallon tanks. • The baffle wail will be constructed with a bole or knockout at the top of the baffle wall for ventilation and multiple holes or knockouts located in the clear zone ofthe tank (approximately 70 percent of the liquid level of the tank}. The holes or knockouts shall be of sufficient size to prevent plugging from raw sewage. IoiZ Hpr .su uts uc.~+~+p vougias t~~oom oau-~+uu-ut~~u p.4 Sewers December 1998 GL-29 A vessel (tank) Aver 1,500 gallons in size shall be configTued to allow solids to deposit in the tank. It is recotmended that the tanks conform to the following approximate configurations: An approximate tank size of 3,000 gallons shall have an equivalent diameter of 6 feet. • An approximate tank size of 6,000 gallons shall have ari equivalent diameter of 8 feet. It is tecomtuended that tank volume over 6,00© gallons be accomplished with tanks in series to facilitate tank pumping. Lf tanks are placed in series, a baffle wail will not be required. Tanks shall have a baffle wal .installed that represents two-thirds volume in the first chamber and one-third volume in the secand chamber. It is recommended that the baffle wall shall be constructed as outlined above. lanKS-that are overl,~UD-gallons tof~oluine~s ave three access ports with a minimum diameter of 18 inches, two in the first chamber and one in the second chamber. All tanks will include an inlet tee_ The bottom of the tee will be extended to 18 inches below the liquid level. A STEPdSDG tank shall contain detention volume, tivorking volume, and storage volume. B. Detention Volume STEP/SDG The detention volume or liquid volume of a STEP or SDG tank that serves a single-family-home or small business`shall be atninimum of950 gallons. Detention volume is defined as the volume of liquid below the "OFF" switch (STEP} or the outlet pipe {SDG). Tanks that serve structures with higher wastewater discharge volumes shall be sized in accordance with the following equation: V = ] .5 Q (residential strength wastz) V = 2.OQ (nonresidential strength waste) Where: V =Liquid volume Q =Peak day .flow for the structure being served Ttte equation provides the minimum liquid volume within the STEP/SDG tank. The tank shall also contain sufficient working volume and storage volume. Liquid volume shall be approximately 65 to 75 percent of the total lank volume. C. R'orking Volume STEPlGF The working volume shall be greater than the difference between the peak influent flow and the discharge of the STEP or grinder pump over a period of time estimated to be the peak duration. Working volume is defrned as the volume between the "ON" and the "OFF" switch. 2oF~ Apr ~U Utt U~:44p Douglas bloom F~E~NS7ATE ;3fiU-4UU-UttLti p. ~ College of Agricultural Sciences Cooperative Extension Agrcutturcct and Biotogicc~i L~'ngineering F-161 Segtic'Tank Pumping A. R. Jarrett, Professor, Agricultural Engineering Septic-tanks are commonly used as a part of on lot wastewater disposal systems. Septic tanks remove settleable and floatable solids froth the wastewater. The clarified septic tank effluent is then passed on to additional treatmentptocesses or is distributedto the soil absorption area. Removing the solids from the wastewater protects the soil absorption a:ea from cloggingaadfaflwe. The septic tank is asingle- or multi-chamber tank that receives the raw wastewater from the home. Until recently, septic tanks were most often single chamber tanks. Based on recent research results, Pennsylvania Department of Environmental Protection now requires all newand upgrzded on-lot wastewater disposal systetfls'to fiave a two=cTiamlier septic tank'similar to the one showninFigure 1. The ttyo-chamber tank provides enhanced removal of solids by passing the wastewater throuDh each ofthe two tank chambers. This allows the heavier solids to settle as sludge and the lighter particles to float to the surface as scum. Up to SQ wasr frotrt es[di perce~rt of the solids retained in the tank decompose; the remainder accumulate in the tank. Biological and chemical additives are not needed to and or accelerate decomposition. The septic tank outlet must also be equipped ~+izh a solids retainer that further enhances the tanks ability to capture solids. As the on-lot wastewater disposal s}~siem is used, sludge continues to accumulate in the bottom of the septic tank chambers. Properly sized septic tanI:s (see Table ])are large enough to safely store up to three years of sludge and scum. As the tank volume filled with sludge and scum increases, wastewater is retained in the tank for less time and the solids removal process becomes less effective and more solids escape into the soil absorption area: if too"ranch stodge accumi~afes, the waste4vater's solids will tlowta the soil absorption field causing system failure. To prevent this, the tank must be pumped periodically. The material pumped is known as septage. 1=lfluentto aLsorptiorl arEa ~.ro~LjS 16t2iSr~P C Figure 1. cross-seetio~: of a tv~a-chamber septic tarz~ .An Equzl Qpportuniiy University College of Agricuttnral Sci~ces, t3.S. L1e~artrnnnerilt of Agriculture, and Pennsylvania Counties Cooperating Access Pori ~a:...~..~:..._ Apr 3U US Uz:45p Douglas t3loom ;~bU-4UU-Uitlt3 p.b FV4~: "Ta4~artta Terra iVIuti family housing. Subject: F1~V: Tahoma Terra Muti family housing. From: "Tim Gibson" <jimg a(}ci.yelrn.~va.us> Date: tired, 5 Mar 2008 16:03:19 -0800 To: <rgdinc~~fairpoint.net>, "Steve Harrington" <steveh~ci.yelm.wa.us>, "Clint Pierpaint" <clint.pierpoint c~r,kpff.com> For your information. Jim Gibson P,E. Crfy of Yetm, Development Review Er~yineer PO Box 479 Ye1m.lNA. 98597 Ph. 360.458.8438 Fx. 360.458.3144 jini~r;`u~ci. relrrl. wc. 2rs __ From: ]im Gibson Sent: Wednesday, March 05, 2008 4:02 PM To: Jon Yanasak Subject: RE: Tahoma Terra Muti family housing, Jon - Thanks for the clarification. I will forward to contractor and engineer. Jim Gibson P,E. Cify of Yefm, Devefoprnent Review Enyirieer PJ Box 479 Yelm, INA. 98597 Ph. 360.458.8438 Fx_ 360.458.3144 %rl1 J°i(1'[Cf.l'Gi7Yl. Ft%f7.2[S From: Jon Yanasak Sent: Wednesday, March 05, 2008 1:45 PM To: Jim Gibson Subject: Tahoma Terra Muti family housing. Jim, I understand that some confusion existed with regard to whether or not we would be requiring a baffle wali in the 3000 gallon holding tanks for the Multi-Family project. Unfortunately, 1 had given Randy some bad information before he went to the pre-con this morning as the prints that we have are incomplete and show such things as round tanks etc. I was in the middle of another project when Randy came to me for clarification on what you and I had agreed on before you left for vacation. Sorry about the confusion. Here is what we want: The 3000 gallon tanks should NOT have a baffle wall. The 1500 gallon pump tanks SHOULD have a baffle wall. I have actually given this some more thought and I'm C~K with this one, but in the future I would rather see the pump tank also be a 3040 gallon tank due to the issue of reserve capacity. With the 1500 gallon pump tank we had better respond to an alarm rapidly! Wiih 8 units being served by this 1500 gallon tank, it won't take long to back-up into the buildings. Jon Yanasak City of Yelm Sewer Dept. Mgr 1 of 2 4x`7;'2003 4:14 PM Hpr :su uts uc45p uougias tsioom eau-4uu-uzs~u p. i FUG: Taho~a Tena it.~luti family housing. Po Box 479 Yelm Wa 98597 Phone 360-458-8411 Fax 360-458-$166 jony@ci.yelm.wa.us 2 of 2 9r7?2003 4: l4 PM ~~W _~~ N '~ b ~~_ D~~A p~C vC Z O Z~° v ~~ W~~ Q ~ .~ m z ,at ~~~ N rn ~° m t~ O z ~ ~~` ~~ ~~ DZ ~°