Community Assessment Report - Onsite Sewage Treatment ...

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Design flows would impact permitting of any wastewater alternative. Average daily flowestimates dictate the level of treatment required and other permitting requirements. For averagedaily flows greater than 10,000 gallons per day within a ½ mile radius of each SSTS owned byone entity, permitting is completed through a Minnesota Pollution Control Agency SDS Permit.Future SSTS with an average daily flow between 5,000 and 10,000 gallons per day would bepermitted by Chisago County using Minnesota Rules Chapters 7080-7083 and would beconsidered a midsized SSTS (MSTS). In addition, SSTS with an average daily flow between2,500 and 5,000 gallons per day are considered large ISTS (LISTS). LISTS are also required tomeet MPCA design guidance, including design guidance for nitrogen reduction or bestmanagement practices. Greater permitting effort increases the overall cost of SSTS design,construction, and operation and maintenance as more research and investigation is requiredupfront and pretreatment of effluent may also be required. Table 4 also highlights permittingrequirements for individual and cluster treatment options based on average daily flows for thesystem alternatives.3.3.1 Collection SystemFour collection system methods to convey wastewater or effluent to the cluster system treatmentand dispersal sites are available:• gravity collection via septic tank effluent gravity systems (STEG);• gravity raw effluent collection to a large septic tank located near the cluster site;• grinder pump basins at each home to a low pressure force main; and• septic tank effluent pump (STEP) system at each residence to a small diameter forcemain.Based on topography and depth to groundwater of the area, pressure collection would be themost water-tight and reliable long term collection method. In addition, the cost of installing anew, water tight lift station relative to the small population of the CAR area makes pressurecollection the least expensive collection method. The two pressure options employ similartechnologies. A grinder basin sends solids to the treatment site. With a STEP system, solids areT:\2797-01 Chisago County\CAR\ROLLINGS SHORES CAR 090712.docx3-10
etained at all individual properties. STEP collection does not require the same level of hydraulicretention at the treatment site as solids remain at each parcel.<strong>Onsite</strong> solids retention with a STEP system requires less capital cost at the treatment site. Otheradvantages of STEP systems over grinder basins include: utilizing existing septic tanks; greaterreserve capacity during power outages or pump failures; less maintenance required on the forcemain; and longer pump life. For these reasons, the most cost effective collection of solids iswithin individual septic tanks at each residence. New tanks would need to be installed along withthe STEP system. Appendix C illustrates a typical schematic of a STEP tank.STEP systems connect to a small diameter pressurized force main installed in road right of waysand easements. The force main follows topography below frost line (6-9 feet) with air releasemanholes installed at high points in the line. Small diameter force main lines would only transfereffluent with solids management occurring at the individual septic tank. Force mains woulddischarge effluent into a stilling tank at the cluster site.The current collection system lines would need to be replaced with the recommended smalldiameter main. Infiltration and inflow into the current collection system prohibits its reuse aspart of a new system.3.3.2 <strong>Treatment</strong> and Dispersal SystemCost estimates generated for this alternative assume that the residents on the proposed clustersystems would agree to be connected to a cluster system at the same time. Project developmentwould likely re-define properties interested in connecting, which could have an impact on theestimated costs.General locations for this alternative have been identified for the potential of a cluster treatmentand dispersal system. The locations are being used for comparison purposes only to provide apreliminary cost estimate based on length of the collection system, type of dispersal system, etc.At the time of project development these locations, or different locations, would need to beT:\2797-01 Chisago County\CAR\ROLLINGS SHORES CAR 090712.docx3-11
Page 1: Rolling ShoresCommunityAssessment R
Page 4 and 5: 1.0 Introduction1.1 BACKGROUNDThe C
Page 7 and 8: 1.3 REPORT PURPOSEThis report is a
Page 9 and 10: 2.0 Existing Conditions2.1 INTRODUC
Page 11 and 12: 2.3 FINDINGSThe purpose of the site
Page 13 and 14: Photo 1: Wastewater effluent surfac
Page 15 and 16: 3.0 Alternatives Analysis3.1 INTROD
Page 17 and 18: 3.2.2 Private ISTS ProgramIn a priv
Page 19 and 20: ISTS rules dictate that systems tha
Page 21 and 22: with CAR ID#13 is allowed to build
Page 23: Table 4: Estimated Permitting Flow
Page 27 and 28: • Lower operation and maintenance
Page 29 and 30: 4.0 Cost Comparison of Alternatives
Page 31 and 32: The replacement wastewater system A
Page 33 and 34: asis, other considerations such as
Page 35 and 36: analysis over a 25-year period show
Page 37 and 38: 5.0 Summary and Recommendations5.1
Page 39 and 40: • Chisago County would continue t
Page 41 and 42: Project LocationRush Lake 7.5 Minut
Page 43 and 44: 920940920920920920940930920920920!A
Page 45: 13Note: CAR ID#13 will be a holding
Page 48 and 49: Appendix ABackground Information
Page 50 and 51: pores and channels. As a result the
Page 52 and 53: The trench is the most common of th
Page 54 and 55: DRAFT - 5/30/12Septic System Improv
Page 56 and 57: CAR ID#Property Information Drainfi
Page 58 and 59: 03.01358.15!>SB 1948.71503.01358.16
Page 60 and 61: !(03.01358.13!(!A!>SB 1939.30703.01
Page 62 and 63: !>!A03.01358.11!. !.03.01358.12!>SB
Page 64 and 65: 03.00047.1003.00047.00!(SUMP OUT925
Page 66 and 67: 03.01358.06!ACambridge Dr!>SB 1939.
Page 68 and 69: !A03.01358.04Cambridge Dr!A03.01358
Page 70 and 71: !(!>SB 1939.98903.01358.02!ASB 1940
Page 72 and 73: !>03.01358.18470th St!>SB 4935.649S
Page 75 and 76:
Appendix DSoil Borings
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Date Completed:Completed By:Project
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Appendix EFlow Calculations
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LISTS Final Permitting FlowWorkshee
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MSTS Final Permitting FlowWorksheet
Page 105 and 106:
ESTIMATED LISTS CLUSTER CAPITAL COS
Page 107 and 108:
ESTIMATED CLUSTER MSTS CAPITAL COST
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OPERATION AND MAINTENANCE FOR CLUST
Page 111 and 112:
Appendix GChisago County Letters
Page 113 and 114:
Compliance Inspection FormExisting
Page 115 and 116:
Property address: Cambridge Dr, Har
Page 117 and 118:
Easement and property research find
Page 119:
#210968• Signed June 27, 1988•
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