Contaminated Soil

What soil testing can and cannot establish

Contamination may result from spills, leaks, waste handling, contaminated fill, pesticide use, historical manufacturing, or migration from nearby properties. Soil evaluation commonly starts with site history and inspection, followed by sampling when potential concerns warrant investigation.

A Phase II environmental site assessment may use borings, direct-push sampling, test pits, or other methods. Qualified environmental professionals compare results with appropriate screening levels, site-specific risk criteria, and regulatory requirements.

Screening levels help identify conditions that need further evaluation. They are not necessarily cleanup standards. A result above a screening level does not automatically establish a violation or dictate the remedy. Technical data also do not resolve who caused contamination or how cleanup costs should be allocated.

Excavation changes the practical questions

Soil beneath intact industrial pavement presents different exposure concerns from soil disturbed during residential construction. Grading, utility work, and dewatering can uncover buried contamination and create additional exposure pathways or management requirements.

Before exporting or reusing excavated soil, determine how the material must be characterized and managed and whether the proposed destination can accept it. Waste profiling, hazardous waste determinations, manifesting, transportation controls, and special handling may be necessary. Dust, worker protection, stormwater, and odors also need attention.

Contaminated soil is not automatically hazardous waste. California waste classification depends on the material’s characteristics and history and the applicable federal and state requirements. A hauling estimate is not a substitute for that determination.

Soil contamination may extend beyond the excavation

Volatile chemicals can move into soil gas and buildings, raising vapor intrusion concerns. Contaminants may also leach into groundwater or migrate across property boundaries. These pathways can affect investigation scope, disclosure, cleanup, and claims involving neighboring properties.

Evaluating soil before work begins can reduce unexpected disposal costs and delays. A soil management plan should address actual site conditions, applicable agency requirements, construction activities, and responsibility for newly discovered material.

Where CEQA review or other project approvals apply, coordinate soil management commitments with construction plans and mitigation measures.

Agency oversight and transaction terms

California soil cleanup may involve DTSC, a Regional Water Board, local environmental health agencies, or other authorities. Jurisdiction depends on the contamination, affected media, and regulatory program. GeoTracker and EnviroStor identify known matters but do not establish the condition of every property.

Soil conditions can affect price, financing, insurance, closing conditions, access, construction schedules, and post-closing obligations. Buyers and sellers may need additional investigation, a cleanup agreement, or revised terms allocating costs and responsibility. The due diligence checklist can help organize those questions.

For redevelopment, consider whether the intended use requires further investigation or controls. See brownfield redevelopment and the firm’s development and redevelopment guidance.

Questions about contaminated soil