At Grade Manual - garyklinka.com
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1. IV SOIL AND SITE REQUIREMENTS Every at grade design is ultimately matched to the given soil and site characteristics The design approach is based on criteria that all applied wastewater is successfully transported and that the away from the component in a manner that will not influence later wastewater additions effluent is ultimately treated 8 of 33 A Minimum Soil Depth Requirements The minimum soil factors required for successful at grade component performance are listed in Tables 1 2 and 3 Soil evaluations must be in accordance with ch Comm 85 Wis Adm Code In addition soil application rates must be in accordance with ch Comm 83 Wis Adm Code B Other Site Considerations 1 Slopes On a crested site the distribution cell can be situated such that the effluent can move laterally down both slopes A level site allows lateral flow in all directions but may present problems as the water table may rise higher beneath the distribution cell in slowly permeable soils Sloping sites allow the liquid only to move in one direction away from the distribution cell On sloping sites and sites with slowly permeable soils at grade components rely on lateral effluent movement through the upper soil horizons Lateral movement becomes more important as soil permeability decreases Concave sloping sites are sites that have convergence of surface and subsurface drainage Landscape topography that retains or concentrates s2. of total retail 1 area 30 sq ft per patron School with meals and showers Classroom 25 500 students classroom School with meals or showers Classroom 25 400 students classroom School without meals or showers Classroom 25 300 students classroom Self service laundry toilet waste only Clothes washer Self service laundry with only residential clothes Clothes washer 200 washers Swimming pool bathhouse May be high strength waste Oo ojo 2 8 A 2 44 20 14 0 C5 33 of 33
3. 21 of 33 4 Horizontal location of distribution lateral in the distribution cell A Level site with one effluent distribution lateral the lateral is located in the center of distribution cell ____ Level site with more than one effluent distribution lateral the laterals are equally spaced apart with the center two laterals the same distance from center of the cell and the distance from the outside laterals to the edge of the cell being one half the distance between laterals Sloping site with one effluent distribution lateral the effluent distribution lateral is located 2 feet in from up slope edge of total distribution cell Sloping site with more than one effluent distribution lateral one lateral is located 2 feet down slope from the up slope edge of the distribution cell and the others are down slope of the upper lateral and up slope of the mid point of the distribution cell credit width 5 Vertical location of distribution lateral in the distribution cell Elevation of distribution lateral invert gt elevation of original contour directly under distribution lateral 6 inches Elevation of distribution lateral invert gt ft 0 5 ft Elevation of distribution lateral invert ft 6 Determine the location of observation pipes along the length of distribution cell Distance from end of distribution cell to end observation pipes 5 to 10 Distance from end of distribution cell to end observation pipes ft 5
4. 5 Check percent of deflection and actual length of concave distribution cell length Percent of deflection Deflection Effective distribution cell length x 100 Percent of deflection ft ftx 100 Percent of deflection ___ lt 10 Actual distribution cell length of deflection x 0 00265 1 x effective distribution cell length Actual distribution cell length __ 96 x 0 00265 1 x ft Actual distribution cell length ft 20 of 33 6 Determine the linear loading rate LLR if the soil application rate of any horizon within 12 inches below the distribution cell has a soil application rate of lt 0 3 gal ft day If the LLR exceeds 4 5 gal ft day for such soils the component must be lengthened to reduce the LLR to 4 5 gal ft day or less LLR DWF B LLR gal day ft LLR gal day ft D Design of entire at grade component 1 Determine the total width of distribution cell For level site the total width of the distribution cell TW is equal to or greater than the effective distribution cell credit width A For sloping site the total width of the distribution cell TW is equal to or greater than the effective distribution cell credit width A 2 feet TW gt A 2 feet TW gt ft 2 feet TW ft 2 Determine the overall width W of the component W 2 TW 10 ft gt ft 10 ft W ft 3 Determine the overall length L of the component L gt B 10ft L gt ft 10 ft L ft
5. Inspections Inspection shall be made in accordance with ch 145 20 Wis Stats and s Comm 83 26 Wis Adm Code The inspection form on the following two pages may be used The inspection of the component installation and or plans is to verify that the component conforms to specifications listed in Tables 1 3 of this manual and the approved plans 29 of 33 POWTS INSPECTION REPORT ATTACH TO PERMIT GENERAL INFORMATION Permit Holder s Name LI City LJ Village L Town of Sanitary Permit No Plan ID No Tax Parcel No Property Address if Available TANK INFORMATION SETBACKS MANUFACTURER CAPACITY P L WELL BLDG VENT TO ROAD Model AIR INTAKE SEPTIC DENEN ae DOSING AERATION PUMP SIPHON INFORMATION FORCE MAIN INFORMATION FRICTION LOSS Diameter Dist To Well Component Head TDH As Built TDH Design SOIL ABSORPTION COMPONENT COVER MATERIAL Cell Width Cell Length Cell Depth Horizontal No of Cells Separation DISTRIBUTION COMPONENT Elevation data on back of form Header Manifold Distribution Pipe s Hole Spacing Obsv Tubes Inst amp No Length Dia Lengh Dia Spacing To 3 2 SOIL COVER DEVIATIONS FROM APPROVED PLAN COMMENTS Persons present discrepancies etc COMPONENTS NOT INSPECTED Plan Revision Required Date Signature of Inspector Cert Number O Yes No 30 of 33 ELEVATION DATA Backsight Height of Comments Ben
6. and geotextile fabric barrier l Component Sizing 1 For one and two family dwellings the number of bedrooms shall be included 2 For public buildings the sizing calculations shall be included 28 of 33 J Tank and Pump Siphon Information 1 Construction details for site constructed tanks Note site constructed tanks that do not have a valid plumbing product approval are not included within the scope of this manual and must be submitted as individual site designs Size model number and manufacturer information for prefabricated tank s Installation information must include vent and access opening locations depth to inlet and height elevation of freeboard if applicable Anchoring information shall be provided whenever a tank is located within the 100 year floodplain and or the depth to seasonal soil saturation indicates anchoring is necessary to prevent flotation of the tank Notation of pump or siphon model pump performance curve friction loss for force main and calculation for total dynamic head Notation of high water alarm manufacturer and model number Cross section of tank chamber to include storage volumes connections for piping vents and power pump off setting dosing cycle and volume high water alarm setting and storage volume above the high water alarm Cross section of two compartments tanks or tanks installed in series shall include information listed above K
7. component 1 Determine the total width of distribution cell For level site the total width of the distribution cell TW is equal to or greater than the effective distribution cell credit width A TW2A 10 ft For sloping site the total width of the distribution cell TW is equal to or greater than the effective distribution cell credit width A 2 feet TW gt 2 feet TW ft 2 feet TW ft 2 Determine the overall width W of the component We 10 ft 10 ft W 20 ft W 2 TW 10 ft 3 Determine the overall length L of the component L2 B 10ft L gt 75 ft410ft L 85 ft 4 Horizontal location of distribution lateral in the distribution cell X Level site with one effluent distribution lateral the lateral is located in the center of distribution cell Level site with more than one effluent distribution lateral the laterals are equally spaced apart with the center two laterals the same distance from center of the cell and 25 of 33 the distance from the outside laterals to the edge of the cell being one half the distance between laterals Sloping site with one effluent distribution lateral the effluent distribution lateral is located 2 feet in from up slope edge of total distribution cell Sloping site with two effluent distribution laterals one lateral is located 2 feet down slope from the up slope edge of the distribution cell and the others are down slope of the upper lateral
8. e g index page 2 Submittal of additional information requested during plan review or questions concerning a specific plan shall be referenced to the Identification number assigned to that plan by the reviewing agency 3 Plans or documents must be permanent legible copies or originals C Forms and Fees A current version of a completed Application For Review form SBD 10577 along with proper fees must be included with plans submitted to the department An Application can be downloaded at www commerce wi gov If plans are to be submitted to a designated county plan review agent the agent should be contacted for information regarding application forms and fees D Soils Information 1 A completed Soils Evaluation Report form SBD 8330 signed and dated by a certified soil tester with credential number 2 Separate sheet showing the location of all borings The location of all borings and observation pits must be able to be identified on the plot plan E Documentation 1 Architects engineers or designers shall sign seal and date each page of the submittal or sign seal and date index page which is attached to the bound set 2 Master Plumbers and Master Plumbers Restricted Service shall sign date and include their license number on each page of the submittal or sign and date an index page which is attached to each bound set 3 At least three sets of plans and specifications clear permanent and legible shall be s
9. length of component must be equal to or greater than the distribution cell length B plus 10 ft for soil cover L gt B 10ft NOTE Greater lengths for landscaping purposes are satisfactory e Horizontal location of distribution lateral in the distribution cell 1 Level site with one effluent distribution lateral the lateral is located in the center of distribution cell 2 Level site with more than one effluent distribution lateral the laterals are equally spaced apart with the center two laterals the same distance from center of the cell and the distance from the outside laterals to the edge of the cell being one half the lateral spacing 3 Sloping site with one lateral the effluent distribution lateral is located 2 feet down slope from up slope edge of the distribution cell 4 Sloping site with more than one effluent distribution lateral one lateral is located 2 feet down slope from the up slope edge of the distribution cell and the other s is are down slope of the upper lateral and up slope of the mid point of the distribution cell effective width f Vertical location of distribution lateral in the distribution cell The distribution lateral must be at least 6 inches above the elevation of original grade before plowing 13 of 33 g Determine the height of the component 1 Height of component over the distribution lateral must be equal to or greater than 6 inches of aggregate beneath distribution pipe plus the n
10. method especially in fine textured soils Rototilling or other means that pulverize the soil is not acceptable The important point is that an uncompacted rough unsmeared surface be left The aggregate will intermingle between the clods of soil which maintains the infiltration rate into the natural soil 6 The required observation pipes must have slots on the bottom 6 inches of the observation pipe Installations of all observation pipes include a suitable means of anchoring See Figure 5 Water tight cap 4 min dia 6 min Infiltrative surface Water Closet Collar Bar 3 8 min dia Figure 5 Observation pipes 7 Immediate application of at least 6 inches of aggregate is required after plowing Shape the aggregate to obtain a uniform minimum depth of at least 6 inches above the original 15 of 33 grade All vehicular traffic is prohibited on the plowed area On sloping sites vehicle traffic is also prohibited for 15 ft down slope and 10 ft on both sides of level sites If it rains after the plowing is completed wait until the soil dries out before continuing construction and contact the local inspector for a determination on the damage done by rainfall 8 Place the effluent distribution lateral s on the aggregate Connect the lateral s using the needed connections and piping to the force main pipe from the dosing chamber Slope the piping from the lateral s to the force main pipe or lay the effluen
11. to divert surface water around the component and sodded or seeded and mulched Installation inspection In accordance with ch Comm 83 Wis Adm Management In accordance with ch Comm 83 Wis Adm Code and this manual Il DEFINITIONS Definitions not found in this section are located in ch Comm 81 of the Wisconsin Administrative Code or the terms use the standard dictionary definition A At grade means an on site wastewater treatment and distribution component The component contains a distribution cell consisting of aggregate and a distribution network on top of the plowed in situ soil and is covered by soil B Component Area means the effective in situ soil surface area available for infiltration of effluent from the distribution cell and the surrounding cover material C Concave Site means a slope shape where surface drainage may converge into a limited area 6 of 33 D Distribution cell means a layer of stone aggregate or synthetic aggregate that receives effluent from a distribution network and distributes that effluent onto a plowed in situ soil dispersal area E Slowly Permeable Soil means soil with textural classifications of clay loams and silty clay loams that exhibit a moderate grade of structure and loams silt loams and silts with weak grades of structure or soils with weak to moderate grades of platy structure according to the US Department of Agriculture Natural Resource Conservatio
12. when the power comes on or when the pump is repaired may cause the distribution component to over load In this situation the pump chamber should be pumped by a certified septage servicing operator before pump cycling begins or other measures shall be used to dose the at grade component with only the proper amount of influent This may include manual operation of the pump controls until such time the pump chamber has reached its normal level E Performance Performance monitoring must be completed on at grade components installed in accordance with this manual 17 of 33 1 The frequency of monitoring must be a At least once every three years after installation and b At time of problem complaint or failure 2 The minimum criteria addressed in performance monitoring of at grade components are a Type of use b Age of component c Nuisance factors such as odors or user complaints d Mechanical malfunction within the component including problems with valves or other mechanical or plumbing components e Material fatigue or failure including durability or corrosion as related to construction or structural design f Neglect or improper use such as overloading the design rate poor maintenance of vegetative cover inappropriate cover over the at grade or inappropriate activity over the at grade component g Installation problems such as compaction or displacement of soil improper orientation or location h Pretreatmen
13. with poor construction results in component failure It is emphasized that the soil only be plowed when it is not frozen and the moisture content is low to avoid compaction and puddling Consequently installations are to be made only when the soil is dry as required The construction plan to be followed includes A Equipment Proper equipment is essential Track type tractors or other equipment that will not compact the at grade area or the down slope area are required B Sanitary Permit Prior to the construction of the component a state Sanitary Permit shall be obtained and posted in a clearly visible location on the site Arrangements for inspection s must also be made with the governmental unit issuing the Sanitary Permit NOTE When a POWTS is located or will be located on property owned by the state the Sanitary Permit shall be obtained from the department Arrangements for inspections s shall be made with the department C Construction Procedures 1 Check the moisture content of the soil to a depth of 8 inches or to the anticipated plow depth whichever is greater Smearing and compacting wet soil will result in reducing the infiltration capacity of the soil Proper soil moisture content can be determined by rolling a 14 of 33 soil sample between the hands f it rolls into a 1 4 inch wire the site is too wet to prepare If it crumbles site preparation can proceed If the site is too wet to prepare do not proceed unti
14. AT GRADE USING PRESSURE DISTRIBUTION COMPONENT MANUAL FOR PRIVATE ONSITE WASTEWATER TREATMENT SYSTEMS Version 2 0 State of Wisconsin Department of Commerce Division of Safety and Buildings SBD 10854 P N 03 07 TABLE OF CONTENTS Page l Introduction and Specifications 3 Il Definitions 6 Ill Description and Principle of Operation 7 IV Soil and Site Requirements 8 V Cover Material 9 VI Design 10 VII Site Preparation and Construction 14 VIII Operation Maintenance and Performance Monitoring 16 IX References 18 X At grade Worksheet 19 Example Worksheet 23 XII Plan Submittal and Installation Inspection 27 Table 4 32 Published on March 01 2007 by Dept of Commerce Division of Safety and Buildings Safety and Buildings Publication SBD 10854 P N 03 07 ADA Statement The Department of Commerce is an equal opportunity service provider and employer If you need assistance to access services or need material in an alternate format please contact the Department at 608 266 3151 or TTY 608 264 8777 2 of 33 INTRODUCTION AND SPECIFICATIONS This Private Onsite Wastewater Treatment System POWTS component manual provides design construction inspection operation and maintenance specifications for an at grade component Violations of this manual constitute a violation of chs Comm 83 and 84 Wis Adm Code The at grade component must receive influent flows and loads less than or equal to thos
15. NS Slope of original grade lt 25 within the component area Vertical depth of in situ soil between bottom gt To depth required by s Comm 83 Table of distribution cell and seasonal saturation 83 44 3 Wis Adm Code defined by redoximorphic features groundwater or bedrock Effluent application By use of a pressure distribution network conforming to Department of Commerce publications SBD 10573 P or SBD 10706 P entitled Pressure Distribution Component Manual for Private Onsite Wastewater Treatment Systems and based on pipe sizing methods contained in Small Scale Waste Management Project publication 9 6 entitled Design of Pressure Distribution Networks for Septic Tank Soil Absorption Systems Piping Material in the distribution system Meets requirements of s Comm 84 30 2 Wis Adm Code for its intended use Piping material for observation and vent pipes Meets requirements of s Comm 84 30 Table 84 30 1 Wis Adm Code Distribution cell aggregate material MER requirements of s Comm 84 30 6 Wis Adm Code Fabric cover of distribution cell when Sees fabric meeting s Comm aggregate is used 84 30 6 g Wis Adm Code Location of distribution lateral s for level Equally from the center of the sites distribution cell Location of distribution lateral s for sloping Most up slope lateral at 2 feet from up slope sites edge of distribution cell If more than one no lateral may be installed in th
16. aily flows and loads without causing surface seepage or groundwater pollution Consequently the effective distribution cell area must be sufficiently large enough to absorb the effluent into the underlying soil Design of the at grade includes the following three steps 1 calculating the design wastewater flow 2 design of the distribution cell and 3 design of the entire at grade component Each step is discussed A design example is included at the end of this manual 1 Design Wastewater Flow Calculations a One and two family dwellings Effective distribution cell size for one and two family dwelling application is determined by first calculating the design wastewater flow DWF To calculate DWF use Formula 1 Formula 1 DWF 150 gallons day bedroom b Public Facilities Effective distribution cell size for public facilities application is determined by calculating the DWF using Formula 2 Public facility estimated daily wastewater flows are listed in Table 4 at the end of this manual Facilities that are not listed in Table 4 are not included in this manual Many commercial facilities have high BODs TSS and FOG fats oils and grease which must be pretreated in order to bring their values down to an acceptable range before entering into the at grade component described in this manual Formula 2 DWF Sum of each estimated wastewater flow per source per day from Table 4 x 1 5 10 of 33 2 Design of the Distribution ce
17. and up slope of the mid point of the distribution cell credit width 5 Vertical location of distribution lateral in the distribution cell Elevation of distribution lateral invert gt elevation of original contour directly under distribution lateral 6 inches Elevation of distribution lateral invert 2 105 ft 0 5 ft Elevation of distribution lateral invert 2 105 5 ft 6 Determine the location of observation pipes along the length of distribution cell Distance from end of distribution cell to end observation pipes B 5 to 10 Distance from end of distribution cell to end observation pipes 75 ft 5 to 10 Distance from end of distribution cell to end observation pipes _ 12 5 ft 26 of 33 XII PLAN SUBMITTAL AND INSTALLATION INSPECTION A Plan Submittal In order to installa POWTS correctly it is important to develop plans that will be used to guide the installation The following checklist may be used when preparing plans for review Conformance to the list is not a guarantee of plan approval Additional information may be needed or requested to address unusual or unique characteristics of a particular project Contact the reviewing agency for specific plan submittal requirements which may be different than the list included in this manual B General Submittal Information 1 Legible photocopies of reports forms plans and other documents are acceptable However an original signature is required on certain documents
18. cell area Calculate the distribution cell area by dividing the daily design wastewater flow DWF by the design loading rate DLR Distribution cell area DWF DLR Distribution cell area 450 0 6 gal f day Distribution cell area 750 ft 3 Select an effective distribution cell width A The effective width can not exceed 10 feet A 10 ft 4 Determine the distribution cell length Calculate the distribution cell length B by dividing the required distribution area by the effective distribution cell width A B Distribution cell area A 750 f 10 ft B 75 ft 5 Check percent of deflection and actual length of concave distribution cell length Percent of deflection Deflection Effective distribution cell length x 100 Percent of deflection ft ftx 100 Percent of deflection lt 10 Actual distribution cell length of deflection x 0 00265 1 x effective distribution cell length Actual distribution cell length __ x 0 00265 1 x ft Actual distribution cell length ft 24 of 33 6 Determine the linear loading rate LLR if the soil application rate of any horizon within 12 inches below the distribution cell has a soil application rate of lt 0 3 gal ft day If the LLR exceeds 4 5 gal ft day for such soils the component must be lengthened to reduce the LLR to 4 5 gal ft day or less LLR DWF B LLR gal day ft LLR gal day ft D Design of entire at grade
19. ch mark mark i 1 id CS Dose tank inlet Bottom of dose tank Dist lateral 1 Component elev 1 Dist lateral 2 Component elev 2 Dist lateral 3 Component elev 3 Grade elev 1 Grade elev 2 Grade elev 3 SKETCH OF COMPONENT amp ADDITIONAL COMMENTS 31 of 33 Table 4 Public Facility Wastewater Flows Estimated Wastewater Flow gpd Bedroom Cid Apartment or Condominium Bedroom 100 Assembly hall no kitchen 1 3 Bar or cocktail lounge no meals served 4 Bar or cocktail lounge w meals all paper service Station Bowling alle Bowling alley with bar 150 Camp day and night Camp day use only no meals served Campground or Camping Resort Space with sewer connection and or service building Campground sanitary dump station Catch basin Church no kitchen Church with kitchen Dance hall Day care facility no meals prepared 2 Day care facility with meal preparation 6 Dining hall kitchen waste only without dishwasher Meal served 2 and or food waste grinder Dining hall toilet and kitchen waste without dishwasher Meal served and or food waste grinder Dining hall toilet and kitchen waste with dishwasher Meal served and or food waste grinder Drive in restaurant all paper service with inside seating 0 Drive in restaurant all paper service without inside Vehicle space 10 seating Drive in theater Employees total all
20. e or Two family Dwelling of bedrooms Public Facility Depth to limiting factor inches In situ soil application rate used gal ft day B DESIGN WASTEWATER FLOW DWF 1 One or Two family Dwelling DWF 150 gal day bedroom x of bedrooms 150 gal day bedroom x of bedrooms gal day 2 Public Facilities DWF Sum of each wastewater flow per source per day x 1 5 gal day x 1 5 gal day 19 of 33 C Effective width and length of the distribution cell 1 Determine the design loading rate DLR for the site From Table 83 44 1 or 2 Wis Adm Code select the soil application rate for the most restrictive soil horizon that may affect treatment and dispersal The soil application rate selected from Table 83 44 1 or 2 Wis Adm Code is the design loading rate DLR for the site DLR gal ft day 2 Determine the distribution cell area Calculate the distribution cell area by dividing the daily design wastewater flow DWF by the design loading rate DLR Distribution cell area DWF DLR Distribution cell area gpd gal ft day Distribution cell area ft 3 Select an effective distribution cell width A The effective width can not exceed 10 feet A ft 4 Determine the distribution cell length Calculate the distribution cell length B by dividing the required distribution area by the effective distribution cell width A Distribution cell area A B ft ft B __ ft
21. e lower half of distribution cell Number of observation pipes per distribution gt Two extending from distribution cell cell infiltrative surface to finished grade Location of observation pipes for level Along opposite ends of distribution cell Each components at a distance equal of 1 5 to 1 10 of the distribution cell length measured from the end of the cell Location of observation pipes for components Along the downslope toe at opposite ends of on a slope distribution cell Each at a distance equal of 1 5 to 1 10 of the distribution cell length measured from the end of the cell 5 of 38 Table 3 OTHER SPECIFICATIONS continued Cover material Fertile soil material i e topsoil containing less than 15 gravel by volume and no rock fragments greater than 3 inches diameter The texture and structure of the soil cover provides adequate water holding capacity to sustain grasses to prevent erosion promotes runoff from precipitation events and allows atmospheric diffusion to the distribution cell below the soil cover Soil finer than silt loam is not recommended Limited activities during component Unless otherwise specifically allowed in this construction manual vehicular traffic excavation and soil compaction are prohibited in The plowed area and For sloping sites 15 feet down slope of component area For level sites 10 feet on both sides of component area Erosion and frost protection Graded
22. e specified in Table 1 When designed installed and maintained in accordance with this manual the at grade component provides treatment and dispersal of domestic wastewater in conformance with ch Comm 83 of the Wis Adm Code Note Detailed plans and specifications must be developed and submitted for review and approval to the governing unit having authority over the plan review In addition a state Sanitary Permit must be obtained from the department or governmental unit having jurisdiction See Section XII for more details Table 1 INFLUENT FLOWS AND LOADS Design Wastewater flow DWF 5000 gal day Monthly average value of Fats Oil In accordance with s Comm 83 44 2 a Wis Adm and Grease FOG Code Monthly average value of five day In accordance with s Comm 83 44 2 a Wis Adm Biochemical Oxygen Demand Code BODs Monthly average value of Total In accordance with s Comm 83 44 2 a Wis Adm Suspended Solids TSS Code Volume of a single dose gt 5 times the void volume of distribution lateral s and lt 20 of the design wastewater flow Design wastewater flow DWF from In accordance with s Comm 83 43 2 3 4 and 5 one and two family dwellings Wis Adm Code Design wastewater flow DWF from gt 150 of estimated wastewater flow in accordance public facilities with Table 4 of this manual or s Comm 83 43 6 Wis Adm Code Linear loading rate for components lt 4 5 gal ft with in situ soils
23. ffluent is distributed into the distribution cell where it flows into the soil where it undergoes biological chemical and physical treatment and dispersal into the environment See Figures 1 2 and 3 for examples of a typical at grade component Cover material consisting of soil provides frost protection and moisture retention sufficient to maintain a good vegetative cover The in situ soil serves as the treatment medium and disperses the effluent into the environment Cover material Distribution lateral Distribution cell Original grade surface Plowed area 3 3 Figure 1 A cross section of a POWTS at grade component 7 of 33 Figure 2 Level Site At Grade ee m www ew 4 eee Observation Pipe Aggregate gt 44 Soil Cover Plowed Area Figure 3 Sloping Site At Grade eee Observation Pipe Aggregate gt sd Soil Cover Plowed Area P t 1 This manual specifies site characteristics design criteria and construction techniques for an at grade component to provide treatment and dispersal of domestic wastewater meeting the standards of s Comm 83 44 2 Wis Adm Code In an at grade component design using pressure distribution the effluent enters the more permeable topsoil over a large area where it can move laterally until absorbed by the less permeable subsoil
24. having a soil application rate of lt 0 3 gal ft day within 12 inches of distribution cell Wastewater particle size lt 1 8 inch Distribution orifice spacing gt 1 orifice for every 2 linear feet of distribution cell 3 of 33 Table 2 SIZE AND ORIENTATION Total effective distribution cell area gt Design wastewater flow soil application rate for the most restrictive soil horizon that may affect treatment and dispersal Soil application rates are listed in s Comm 83 Table 83 44 1 or 2 Wis Adm Code Effective distribution cell credit width A 10 ft or width of distribution cell whichever is less Width of aggregate for level sites 2 Effective distribution cell width Width of aggregate for sloping sites gt Effective distribution cell width 2 ft Width of component area W gt Effective distribution cell width 10 ft Effective distribution cell length B gt Design wastewater flow DWF Design soil application rate DAR Distribution cell width A Length of component area L gt Effective distribution cell length 10 ft Depth of aggregate distribution cell at gt 8 inches nominal diameter of distribution distribution pipe pipe Depth of aggregate distribution cell at edge Depth of soil cover over distribution cell Orientation Longest dimension parallel to surface grade contours on sloping sites Deflection of distribution cell on concave 10 slopes 4 of 33 Table 3 OTHER SPECIFICATIO
25. in accordance with the management plan 2 Inspections of the at grade component are required at least once every three years These inspections include checking the liquid levels in the observation pipes and examination for any seepage around the component 3 Traffic except for lawn maintenance on the at grade component is not permitted to avoid frost penetration in winter and to minimize compaction during other times 4 A good water conservation plan within the house or establishment will help assure that the at grade component will not be overloaded D User s Manual A user s manual is to accompany the at grade component and be provided to the owner following installation At a minimum the manual is to contain the following information 1 Diagram s of all components and their location This should include the location of the reserve area if one is provided Names and phone numbers of local governmental unit authority component manufacturer or POWTS service provider to be contacted in the event of component failure or malfunction A management plan that contains information on the periodic inspection maintenance or servicing of the component including electrical mechanical components What activities can or cannot occur on the reserve area if one is provided Notice that the dose chamber if one is utilized may fill due to flow continuing during pump malfunction or power outages One large dose
26. l area is sufficient The actual distribution cell length is calculated using Formula 4 Formula 4 Actual distribution cell length of deflection x 0 00265 1 x effective distribution cell length Where of deflection Determined by Formula 3 0 00265 Conversion factor from percent to feet 1 Constant Actual cell length 2 102 100 98 IR EUR c ppt Fi Eg a au 96 Effective Cell Length of Concave Distribution Cell Figure 4 Concave at grade and Distribution Cell 3 Design of the entire at grade component This includes sizing the total width and length of the distribution cell component height location of the effluent distribution lateral and observation pipes a Determine the total width of distribution cell for level sites the total width of distribution cell TW is equal to or greater than the effective distribution cell credit width A TW2A b For sloping sites the total width of distribution cell is equal to or greater than the effective distribution cell credit width A plus 2 feet TW gt A 2 feet 12 of 33 c Determine the overall width W of the component The minimum width of component must be equal to or greater than the total width of distribution cell plus 10 ft for soil cover W gt TW 10ft NOTE Greater widths for landscaping purposes are satisfactory d Determine the overall length L of the component Minimum overall
27. l it dries 2 Lay out the distribution cell area on the site so that the upslope edge of the effective distribution cell is level or on a contour line points of equal elevation 3 For components in open areas measure the average ground elevation along the up slope edge of the distribution cell For components on uneven sites rough terrain plow the surface before the average ground elevation along the up slope edge of the distribution cell is measured The average elevation is referenced to a benchmark for future use This is necessary to determine the bottom elevation of the distribution cell Note that the entire component area L x W is plowed 4 Determine where the force main from the dosing chamber will connect to the distribution system in the distribution cell Place the pipe either before or after plowing If the force main is to be installed in the down slope area the trench for the force main may not be wider than 12 inches 5 Cut trees as close as possible to the ground surface and leave stumps remove surface boulders that can be easily rolled off remove vegetation over 6 inches long by mowing and removing cut vegetation Prepare the site by plowing the surface soil perpendicular to the direction of the slope and to a depth of 7 8 inches so as to eliminate any surface mat that could impede the vertical flow of liquid into the in situ soil Plowing with a Moldboard plow is done along contours Chisel plowing is the preferred
28. ll This section determines the required effective cell area of the distribution cell as well as the dimensions for the soil cover material a Determine the design loading rate DLR for the site The design loading rate equals the soil application rate of the soil horizon in contact with the distribution cell Use Table 83 44 1 or 2 Wis Adm Code to determine the soil application rate Note that s Comm 83 44 4 c Wis Adm Code requires designers to consider more restrictive subsoil horizons b Determine the effective area of the distribution cell The effective area of the distribution cell is calculated by dividing design wastewater flow DWF by the design loading rate DLR c Choose an effective distribution cell credit width The effective credit width can not exceed 10 ft Determine the distribution cell length B The distribution cell length B is calculated by dividing the effective area of the distribution cell by the effective width A of the distribution cell d Determine the linear loading rate LLR The linear loading rate is calculated dividing the design wastewater flow DWF by the distribution cell length B For systems that have in situ soil having a soil application rate lt 0 3 gal ft2 day that are within 12 inches below the distribution cell the linear loading rate LLR can not exceed 4 5 gal ft day If the LLR exceeds 4 5 gal ft day for such soils the component must be lengthened to reduce
29. n Service classification system F Unsaturated flow means liquid flow through a soil media under a negative pressure potential Liquids containing pathogens and pollutants come in direct contact with soil or fill material microsites that enhance wastewater treatment by physical biological and chemical means G Vertical Flow means the downward flow of water or effluent through soil that involves travel along soil surfaces or through soil pores Ill DESCRIPTION AND PRINCIPLE OF OPERATION The operation of the at grade component is a two stage process involving both wastewater treatment and dispersal into the underlying soil Treatment is accomplished predominately by physical and biochemical processes within the soil These processes are affected by the physical characteristics of the effluent wastewater influent application rate temperature and the nature of the receiving soil Physical entrapment increased retention time and conversion of pollutants in the wastewater are important treatment objectives accomplished under unsaturated conditions Pathogens contained in the wastewater are eventually deactivated through filtering retention and adsorption by the soil In addition many pollutants are converted to other chemical forms by oxidation processes The at grade component contains a distribution cell consisting of stone aggregate and a distribution network on top of the plowed in situ soil dispersal area and is covered by soil E
30. ominal diameter of distribution lateral plus 2 inches above the distribution lateral plus 12 inches of soil cover 2 Height of component over the rest of the distribution cell must be equal to or greater than 6 inches of aggregate plus 12 inches of soil cover h Location of the observation pipes 1 Components on a level site must include two observation pipes The observation pipes are along opposite ends of the distribution cell and located at a distance equal to 1 5 to 1 10 of the distribution cell length measured from the end of the cell 2 Components on a sloping site must include two observation pipes The observation pipes are along the down slope toe at opposite ends of the distribution cell and located at a distance equal to 1 5 to 1 10 of the distribution cell length measured from the end of the cell i Distribution Network and Dosing System A pressure distribution network conforming to Department of Commerce publications SBD 10573 P or SBD 10706 P entitled Pressure Distribution Component Manual for Private Onsite Wastewater Treatment Systems and based on pipe sizing methods contained in Small Scale Waste Management Project publication 9 6 entitled Design of Pressure Distribution Networks for Septic Tank Soil Absorption Systems must be used Vil SITE PREPARATION AND CONSTRUCTION Procedures used in the construction of an at grade component are just as critical as the design of the component A good design
31. shifts Floor drain not discharging to catch basin 13 Gas station convenience store Patron minimum 500 patrons 3 0 i35 Gas station with service bay Patron Patron Service ba Service ba 135 Medical office building Doctors nurses medical staff Person 50 Office personnel Person 13 Patients Person 6 5 Migrant labor camp central bathhouse May be high strength waste 13 5 32 of 33 Table 4 Public Facility Wastewater Flows continued Estimated Wastewat er Flow gpd Mobile Home Manufactured home served by its own Bedroom 100 POWTS Nursing Rest Home Community Based Residential Bed space Facilit Patron 75 patrons acre Public shower facilit 10 Restaurant 24 hr dishwasher and or food waste Patron seating space 4 grinder only Restaurant 24 hr kitchen waste only without 1 dishwasher and or food waste grinder Restaurant 24 hr toilet waste Restaurant 24 hr toilet and kitchen waste without dishwasher and or food waste grinder Restaurant 24 hr toilet and kitchen waste with dishwasher and or food waste grinder 2 Restaurant kitchen waste only without dishwasher Patron seating space and or food waste grinder 14 Restaurant toilet and kitchen waste without dishwasher Patron seating space and or food waste grinder Restaurant toilet and kitchen waste with dishwasher Patron seating space 22 and or food waste grinder Retail store Patron 70
32. stribution cell and absorption area means fertile soil material i e topsoil containing less than 1596 gravel by volume and no rock fragments greater than 3 inches diameter The texture and structure of the soil cover provides adequate water holding capacity to sustain grasses to prevent erosion promotes runoff from precipitation events and allows atmospheric diffusion to the distribution cell below the soil cover Soil finer than silt loam is not recommended 9 of 33 VI DESIGN A Location Size and Shape Placement sizing and shaping of the at grade must be in accordance with this manual The means of pressurizing the distribution network must provide equal distribution of effluent along the length of the distribution cell A pressure distribution network conforming to Department of Commerce publications SBD 10573 P or SBD 10706 P entitled Pressure Distribution Component Manual for Private Onsite Wastewater Treatment Systems and based on pipe sizing methods contained in Small Scale Waste Management Project publication 9 6 entitled Design of Pressure Distribution Networks for Septic Tank Soil Absorption Systems must be used B Component Design Detailed plans and specifications must be developed and then reviewed and approved by the governing unit having authority over plan review Design of the at grade component is based on the design wastewater flow and soil characteristics It must be sized such that it can accept the d
33. t component maintenance including dosing frequency structural integrity groundwater intrusion or improper sizing i Pump or siphon chamber maintenance including improper maintenance infiltration structural problems or improper sizing j Ponding in distribution cell prior to the pump cycle Ponding may be evidence of development of a clogging mat or reduced infiltration rates k Siphon or pump malfunction including dosing volume problems pressurization problems breakdown burnout or cycling problems I Overflow or seepage problems as shown by evident or confirmed sewage effluent including backup if due to clogging 3 Reports are to be submitted to the governmental unit or designated agent in accordance with ch Comm 83 Wis Adm Code IX REFERENCES J C Converse E Jerry Tyler and James O Peterson 1990 Wisconsin At Grade Soil Absorption System Siting Design and Construction Manual Small Scale Waste Management Project 15 21 18 of 33 X AT GRADE WORKSHEET AT GRADE WORKSHEET A SITE CONDITIONS Evaluate the site and soils report for the following a Surface water movement b Measure elevations and distances on the site so that slope contours and available areas can be determined c Description of several soil profiles where the component will be located d Determine the limiting conditions such as bedrock high groundwater level soil permeability and setbacks Slope 96 Occupancy On
34. t distribution lateral s level with the perforations down All pipes shall drain after dosing 9 Place at least 2 inches of aggregate over the lateral s 10 Place geotextile fabric conforming to requirements of ch Comm 84 Wis Adm Code over the aggregate 11 Place soil cover material on top of the geotextile fabric and extend the soil cover to the boundaries of the overall component 12 Complete final grading to divert surface water drainage away from the at grade Sod or seed and mulch the entire at grade component Vill OPERATION MAINTENANCE AND PERFORMANCE MONITORING A Owner is Responsible The POWTS owner is responsible for the operation and maintenance of the component The county department or POWTS service provider may make periodic inspections of the components checking for surface discharge and ponded effluent levels in the observation pipes etc The owner or owner s agent is required to submit necessary maintenance reports to the governmental unit or designated agent B Approvals and Inspections Design approvals and site inspection before during and after the construction is accomplished by the governmental unit or other appropriate jurisdiction s in accordance with ss Comm 83 22 and 83 26 Wis Adm Code 16 of 33 C Routine and preventative maintenance aspects 1 Treatment and dose tanks along with related mechanical components are to be inspected routinely and maintained when necessary
35. the LLR to 4 5 gal ft day or less e Concave at grade configuration The maximum deflection of a concave distribution cell of an at grade system is 1096 The percent of deflection of a distribution cell is determined by dividing the amount of deflection by the effective distribution cell length of the concave distribution cell The deflection is the maximum distance between the down slope edge of a concave distribution cell to the length of a perpendicular line that intersects furthest points of the contour line along the down slope edge of the distribution cell The effective distribution cell length of the concave distribution cell is the distance between the furthest points along the contour line of the down slope edge of the concave distribution cell See Figure 4 The deflection of a distribution cell on concave slopes is calculated using Formula 3 Formula 3 f Percent of Deflection Deflection Effective distribution cell length x 100 Where Deflection Maximum distance between the down slope edge of a concave distribution cell to the length of a perpendicular line that intersects furthest points of the contour line along the down slope edge of the distribution cell 11 of 33 Effective distribution cell length Distance between the furthest points along the contour line of the down slope edge of the concave distribution cell 100 Conversion factor The actual distribution cell length must be checked to determine if the cel
36. to 10 Distance from end of distribution cell to end observation pipes ft 22 of 33 XI EXAMPLE WORKSHEET AT GRADE WORKSHEET A SITE CONDITIONS Evaluate the site and soils report for the following 1 Surface water movement 2 Measure elevations and distances on the site so that slope contours and available areas can be determined 3 Description of several soil profiles where the component will be located 4 Determine the limiting conditions such as bedrock high groundwater level soil permeability and setbacks Slope 1 96 Occupancy One or Two family Dwelling of bedrooms 3 _ Public Facility Depth to limiting factor 38 inches In situ soil application used 0 6 gal ft day B DESIGN WASTEWATER FLOW DWF 1 One or Two family Dwelling DWF 150 gal day bedroom x of bedrooms 150 gal day bedroom x 3 of bedrooms 450 gal day 2 Public Facilities DWF Sum of each wastewater flow per source per day x 1 5 gal day x 1 5 gal day 23 of 33 C Effective width and length of the distribution cell 1 Determine the design loading rate DLR for the site From Table 83 44 1 or 2 Wis Adm Code select the soil application rate for the most restrictive soil horizon that may affect treatment and dispersal The soil application rate selected from Table 83 44 1 or 2 Wis Adm Code is the design loading rate DLR for the site DLR 0 6 gal f day 2 Determine the distribution
37. ubmitted to the department Submittals must be on paper measuring at least 8 1 2 by 11 inches Each plan set shall be bound by staples brads or other fasteners Pages which 27 of 33 are held together by rubber bands and or paper clips are not considered to be a bound volume F Plot Plan Information 1 Dimensioned plans or plans drawn to scale scale indicated on plans with property lines parcel size and property boundaries clearly marked 2 Slope directions and percent in component area 3 Benchmark and north arrow 4 Pertinent setbacks distances as per appropriate code 5 Two foot contours or other appropriate contour interval within the system area 6 Location information legal description down to 40 acres and or subdivision block and lot number of platted lands 7 Pertinent existing and proposed buldings wells water lines swimming pools flood plain location and elevation and OHWM designations of navigable waters G Plan View 1 Dimensions for distribution cell s 2 Location of observation pipes 3 Pipe lateral layout which includes the number of laterals pipe material diameter and length and number location and size of orifices 4 Manifold force main locations with materials length and diameter of each H Cross Section of Component 1 Include plowing requirement distribution cell details and cover material 2 Lateral elevation position of observation pipes dimensions of distribution cell
38. ubsurface flows such as swales depressions or potholes is considered an unacceptable at grade location The maximum deflection allowed as listed in Table 2 is 10 Over land surface flow is to be diverted from the site or other methods employed to allow surface flow around the component 2 At grade location Open areas and exposure to sun and wind increase the assistance of evaporation and transpiration in the dispersal of wastewater 3 Sites with trees and large boulders Generally sites with large trees numerous smaller trees or large boulders are less desirable for installing an at grade component These sites create difficulty in preparing the surface and reduce the infiltration area beneath the at grade Rock fragments tree roots stumps and boulders occupy an area thus reducing the amount of soil available for proper treatment If no other site is available trees in the component area of the at grade must be cut off at ground level and boulders that are setting on the ground surface removed A larger infiltrative area is necessary when any of the above conditions are encountered to provide sufficient effective distribution cell area 4 Setback distances The setbacks specified in ch Comm 83 Wis Adm Code for soil subsurface treatment and distribution components apply to at grade components The distances are measured from the perimeter of the effective distribution cell area V COVER MATERIAL The cover material above the di
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