Community Assessment Report - Onsite Sewage Treatment ...

STEP system costs were calculated as shown in Appendix F. The cost of the collection systemtakes into account tank abandonment and new tank costs.Costs assume ownership of the MSTS or LISTS cluster system by the Township and ownershipof ISTS by a private party. The MSTS alternative assumes mound dispersal areas consisting of10 foot wide pressurized beds with a rock dispersal area. MSTS costs including the pretreatmentfor nitrogen have reduced vertical separation requirements (i.e. shorter mounds), as the effluentwill be pretreated by the nitrogen removal technology. The LISTS alternative assumes Type 3mound treatment with three feet of sand in the mound. A detailed Hydrogeological Assessmentat the proposed cluster site to determine if nitrogen removal technology will be required as partof the treatment system will be completed as part of project development. Costs for thisassessment are included within engineering cost estimates in Table 6. The cost of the MSTScluster system also takes into account constructing 1.5 times the amount of mound absorptionarea (i.e. making the mounds longer), as required by the year 2011 version of MN Rules Chapter7081.4.3 SUMMARY OF CAPITAL COSTSSections 4.1 – 4.2 highlight the cost estimates for each of the wastewater infrastructurealternatives. The cost estimates for each alternative assume the entire area would be served bythe alternative chosen. Table 7 is a side by side comparison of the average per unit capital costfor each of the alternatives.Table 7: Summary of Capital CostsAlternative 1ManagedISTSProgramAlternative 2LISTSCluster +ISTSAlternative 3MSTSClusterAlternative 3MSTS Clusterwith NitrogenRemovalTotal Assessed System Costs $ 251,300 $ 420,300 $ 612,400 $ 909,610Average Cost/Dwelling $ 18,000 $ 30,100 $ 43,800 $ 65,000Section 3.0 identifies the necessary components, advantages, and disadvantages of the threealternatives. While an ISTS program is the least expensive alternative on an average per unitT:\2797-01 Chisago County\CAR\ROLLINGS SHORES CAR 090712.docx4-4