Brooklyn MGP ISGS Remediation

Project Overview

IET executed a large-scale In Situ Geochemical Stabilization (ISGS) remediation project for a former manufactured gas plant (MGP) site at 155 3rd Street in Brooklyn, NY. This three-day injection program combined ISGS amendment with hydrogen peroxide for aggressive treatment of coal tar and MGP-related contaminants.

The project utilized IET's specialized injection trailer over two days with comprehensive on-site supervision, neutralization services, and a four-person crew for complex urban site conditions.

Treatment Approach

Technical Approach & ISGS Amendment Delivery

This Brooklyn ISGS project delivered 13,829.76 lbs of ISGS amendment supplemented with 505 lbs of 35% hydrogen peroxide over a 2-day injection program with 3 days of on-site supervision. The H₂O₂ enhancement provides supplementary oxidation capacity — generating hydroxyl radicals that extend the treatment's oxidative reach beyond the permanganate-only reaction pathway. This dual-oxidant approach is particularly effective in dense urban subsurface environments where NAPL is trapped in heterogeneous fill material.

The 4-person specialized crew operated IET's proprietary injection trailer system — a self-contained chemical mixing and injection platform with dual 220-gallon conical tanks, lightning mixers for maintaining reagent suspension, on-board generator, and stainless steel piping. The trailer system enables precise control of injection pressure, flow rate, and reagent concentration — critical parameters for effective NAPL stabilization in the variable fill and native sediment conditions characteristic of Brooklyn's industrial subsurface.

The 2-day injection duration with 3 days of supervision reflects the careful pace required for urban ISGS deployment — allowing time for amendment hydration, pressure response monitoring, and real-time adjustment of injection parameters based on subsurface feedback. This measured approach maximizes NAPL contact with the permanganate-based amendment and ensures thorough stabilization of the source zone before demobilization.

Urban NAPL Site Context & Brooklyn Geology

Brooklyn, New York's subsurface consists of variable fill material — historic demolition debris, ash, and native sediment — overlying glacial till and outwash deposits from the Wisconsin glaciation. The fill material, commonly 5–20 feet thick in industrial areas, creates heterogeneous subsurface conditions with variable permeability, buried obstructions, and intermixed contaminants from over a century of urban industrial activity. The shallow water table (typically 5–15 feet bgs) flows through these fill and glacial deposits toward surrounding waterways.

ISGS is particularly well-suited for Brooklyn's NAPL challenges because the technology stabilizes NAPL in place rather than attempting to fully destroy it — an approach that is both more cost-effective and more reliable for the complex NAPL distributions found in urban fill. The permanganate-based amendment polymerizes organic contaminants, physically coating NAPL globules with manganese oxide precipitate and reducing contaminant flux to groundwater by 80% or more. This project was completed June 6, 2025, demonstrating IET's ongoing ISGS deployment capability in the New York City market.