Ivins hears draft sewer master plan; consultant proposes $621.55 per-ERU sewer impact fee and $7M of collection projects

Consultants from Bowen Collins and Associates presented a draft sewer master plan to the Ivins City Council on May 1, saying the city’s collection system has capacity today but will require targeted upgrades as growth continues.

Aaron Anderson, a consultant on the project, said the team’s current count of equivalent residential units (ERUs) in the system is "it's actually 4,628," and that the analysis uses a planning domestic flow "we have a domestic flow per ERU of a 159 gallons per day" (175 gpd per ERU including an infiltration allowance). Using those metrics and forecasted growth, the firm estimated Ivins will add roughly 3,000 ERUs in the next 10 years and reach a build-out of about 11,551 ERUs over the long term, including approximately 500 ERUs in a planned annexation area.

The presentation mapped projects the consultants recommend over a 10‑year planning window and beyond. Near-term items include an Old Highway 91 extension with a lift station and force main and a major replacement of the Lower Tuacon Wash sewer line, a project the consultants said would be implemented jointly with Santa Clara City. The consultants estimated just under $7 million of collection-system projects in the 10‑year window; they identified the Lower Tuacon Wash replacement as the single largest item.

Consultants also presented a capital facilities and impact-fee calculation for sewer collection, including an allowance for project financing. The draft impact-fee package calculated a sewer impact fee of $621.55 per ERU for Ivins (this figure reflects buy‑in and the city’s proportionate share of planned 10‑year projects and financing costs). The consultants outlined a financing example that assumed a $2 million bond for part of the Lower Tuacon Wash work, a 20‑year term, 4% interest and a bond-issuance fee; under those assumptions the interest cost would total just under $1 million over 20 years and is included in the impact-fee calculation.

Council members asked technical questions about the assumptions. One council member noted that monthly household water use in some neighborhoods can appear low under conservation, and the consultant responded that design uses average domestic-flow values for ERUs and that the model focuses on peak-day pipe capacity. Consultants emphasized that hydraulic modeling flags pipeline and lift-station capacity issues to guide where upgrades will be needed.

Aaron Anderson said staff and consultants plan to finalize draft reports and return to the council with the master-plan and impact-fee documents for further review and a potential public hearing. "We'll provide those draft reports to the council next week so you can review them at your own leisure and come back with questions," consultants told the council.

Why it matters: the master plan and the proposed impact fee affect where and when sewer lines are upsized, who pays for system expansions (growth via impact fees versus the city), and near-term capital budgeting and rate planning. The consultants and staff noted that portions of the work are shared with Santa Clara and that cost-split and timing must be coordinated.

Next steps: consultants will finalize the master-plan draft and impact-fee analysis, staff will complete a rate analysis for the proposed rehab/replacement budget, and council will be asked to decide whether to set a public hearing on the master plan and impact fees once staff posts the draft materials.