Persulfate PRB Injection — Mentor Ave, Mentor OH

Project Overview

IET supplied a large-scale permeable reactive barrier (PRB) material package at 8667–8679 Mentor Avenue in Mentor, Ohio for Uptown Mentor LLC (Invoice 1 of 3). The program utilized IET's patented ferric iron-activated persulfate system — combining sodium persulfate, potassium persulfate, magnesium oxide, and ferric oxide — to treat subsurface contamination across two treatment areas.

The PRB Area A treatment involved substantial quantities of both sodium and potassium persulfate (8,950 lbs each), activated by ferric oxide (3,580 lbs) and buffered with magnesium oxide (1,306.56 lbs). Area B included partial material delivery with additional magnesium oxide (2,506.82 lbs) and ferric oxide (1,980 lbs).

IET's proprietary ferric iron activation chemistry simultaneously generates sulfate radicals, hydroxyl radicals, and ferrate — providing broad-spectrum oxidation with sustained reaction longevity of 2+ years to prevent contaminant rebound. This multi-phase delivery (Invoice 1 of 3) reflects the scale of this commercial redevelopment remediation program.

Reagent Delivery — Invoice 1 of 3

Project Details

Technical Approach & Ferric Iron-Activated Persulfate Chemistry

IET's ferric iron-activated persulfate system is a patented ISCO technology that simultaneously generates multiple oxidative radical species — sulfate radicals (SO₄•⁻), hydroxyl radicals (•OH), and ferrate (FeO₄²⁻) — from a single injection event. Unlike single-oxidant ISCO approaches that produce only one radical species and have limited reaction longevity, IET's multi-radical system provides broad-spectrum contaminant destruction with sustained reaction activity lasting 2+ years in the subsurface. This extended longevity is the key to preventing contaminant rebound — the re-dissolution and migration of residual contamination after the oxidant is depleted.

For the Mentor Avenue project, IET designed a permeable reactive barrier (PRB) using a combination of sodium persulfate (8,950 lbs) and potassium persulfate (8,950 lbs) as primary oxidants, activated by ferric oxide (3,580 lbs). Magnesium oxide (1,306.56 lbs in Area A, 2,506.82 lbs in Area B) serves as a pH buffer to maintain the subsurface geochemical conditions needed for sustained radical generation. The PRB approach creates a subsurface treatment zone that destroys contaminants as groundwater flows through it — providing long-term plume control without the need for continuous active treatment.

This project represents Invoice 1 of 3 in a multi-phase delivery program, reflecting the scale of the commercial redevelopment remediation at 8667–8679 Mentor Avenue. The multi-phase approach allows IET to deliver large reagent quantities in staged shipments, managing logistics and cash flow while maintaining continuous treatment system deployment. The ferric oxide activator is a key differentiator — it provides sustained activation without the rapid pH swings associated with chelated iron or base activation, enabling the 2+ year reaction longevity that prevents rebound at complex chlorinated solvent and petroleum sites.

Commercial Redevelopment Site Context

Mentor, Ohio is located in Lake County along the Lake Erie shoreline in northeastern Ohio. The shallow geology consists of glacial lacustrine deposits (silt and clay) overlying glacial till (sand, gravel, and clay mixtures), with Devonian-age shale bedrock at depth. The Mentor Avenue corridor is a major commercial district with a history of retail and light industrial use — sites in this area commonly have chlorinated solvent and petroleum contamination from historical dry cleaning, auto service, and commercial operations.

The PRB approach is particularly well-suited for commercial redevelopment sites like this one, where the treatment zone can be installed beneath the future building footprint without disrupting planned construction. The PRB provides long-term groundwater treatment as the plume migrates through the reactive barrier — protecting downgradient receptors and enabling regulatory closure without ongoing active treatment systems. The substantial reagent mass (23,786 lbs of persulfate + activators in PRB Area A alone) reflects the contaminant mass and plume dimensions at this site, with treatment designed to achieve regulatory cleanup standards within the redevelopment timeline.