Agenda - 08-04-1997 - 10a - Laserfiche WebLink

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4 „ of acquiring a more distant site for the sole purpose of developing on-site sewer treatment is not , economically feasible. Alternatives 2 and 3 are both feasible as long term County sewer assessment projects. As for Alternative 2, the US 70 corridor contains approximately 65 existing residential and non- residential units(including the eleven at Boone Mobile Home Park) on 70 lots and parcels having frontage on US 70. Fifteen of those parcels are fairly large and contain a total of approximately 200 undeveloped acres. Counting the development potential of that acreage along with the existing smaller undeveloped lots, the estimated buildout for the US 70 corridor is approximately 250 units. The sewer flow which would be assumed to be generated by 250 residential units could be accommodated in a four inch diameter force main collector line. The estimated engineering/construction/contingency cost to construct the four inch force main collector and service lateral stub-outs that would be necessary to provide build-out level service for just the US 70 corridor as far as Boone Mobile Home Park is approximately $190,000. An assessment cost recovery process based on acreage, lot and front footage should provide for an average assessment of less than$1000 per unit at build-out. Each unit would also be subject to costs for individual on-site pump stations(approximately $3000 each), County tap-on fees (currently$600 per unit) and Town of Hillsborough capital facilities fees(currently $1200 for less than% acre or and $1600 per acre for more than% acre). Using these cost figures(and a$1000 assessment for constructing the collector), the Alternative 2 total initial sewer service cost for typical residential user on a one acre lot would be approximately $6200. The estimated cost of this strategy to Mr. McBroom for one large pump station serving eleven units would be approximately $40,000 or $3600 per unit. Alternative 3 would provide sewer service for approximately 200 existing units or 250 units at buildout in the Perry Hills area for a total of approximately 265 existing units and 500 units at buildout. The majority of the Perry Hills community would be served by 8" gravity collector sewers which would drain to a major pumping station located near the northwest corner of the community. A six inch force main, routed back through Perry Hills and Boone Mobile Home Park and along US 70 to the Efland sewer system, would be required to serve both the Perry Hills and US 70 areas. The properties in the US 70 corridor would tap this force main in a manner similar to that proposed for Alternative 2. The total cost of Alternative 3 is estimated at approximately $2.3 million. The differences between the types of sewer service(gravity versus force main) and the associated on- and off-site costs can be expected to complicate the assessment process for Alternative 3. On a simple per build-out unit basis, the assessment would total approximately $4600. However, the assessment could be structured such that it compensated for both the additional on-site costs to those units requiring individual pumping station and the far greater off-site costs associated with developing gravity sewer service. This compensation process could be set up such that gravity sewer customers would pay approximately $6000 in assessment cost, and force main customers would pay $3000 in assessment cost and$3000 for on-site pumping cost. Each customer would still be subject to the County's$600 tap-on fee and the Town's capital facilities fee. Under the compensating assessment strategy for Alternative 3, the total initial sewer service cost for typical residential user on a one acre lot would be approximately$8200. The estimated cost of this strategy to Mr. McBroom, again with one large pump station serving eleven units, would be approximately $62,000 or $5600 per unit. According to Environmental Health section records, the US 70 and Perry Hills area do not report abnormally high levels of septic system failure. It is possible, but unlikely, that the area does have high levels of septic system failures that go undetected or unreported. In the absence of substantiated evidence of serious septic system problems or similar potential public health implications, however, the