Environmental remediation is the process of removing, containing, or treating contamination in soil, groundwater, or surface water to achieve cleanup standards required by regulatory agencies. Remediation obligations can arise from voluntary discovery, enforcement actions, property transactions, and Superfund or state-directed cleanup programs.

CERCLA (the federal Superfund law) imposes liability on four categories of potentially responsible parties (PRPs): current owners and operators of a contaminated facility, past owners and operators at the time of disposal, generators who arranged for the disposal of hazardous substances, and transporters who selected the disposal site. CERCLA liability is strict, joint and several, and retroactive.

CERCLA recognizes the innocent landowner defense for property owners who can demonstrate that they did not know and had no reason to know of contamination at the time of acquisition, and that they conducted appropriate inquiries (all appropriate inquiries or AAI standard under EPA regulations) before purchase. This defense must be established proactively and requires careful documentation.

A Phase I ESA is a non-invasive investigation of a property's historical uses, surrounding properties, and regulatory databases to identify recognized environmental conditions (RECs) that could indicate contamination. It is the first step in satisfying CERCLA's "all appropriate inquiries" requirement for the innocent landowner defense and is standard practice in commercial real estate due diligence.

Natural resource damages (NRDs) are compensation claims brought by federal, state, tribal, and local trustees for injuries to natural resources — such as fisheries, wetlands, groundwater, and wildlife — caused by releases of hazardous substances. NRD claims arise under CERCLA, the Clean Water Act, and state law, and can be pursued by government trustees separate from response cost recovery.

CERCLA allows PRPs who have paid more than their fair share of cleanup costs to seek contribution from other responsible parties. Courts consider equitable factors including the volume and toxicity of hazardous substances each PRP contributed, their degree of involvement, their financial benefit, and their involvement in disposal decisions.

California's HWCL, administered by the Department of Toxic Substances Control (DTSC), governs the generation, handling, transport, treatment, storage, and disposal of hazardous waste in California. It is authorized under RCRA but often imposes additional requirements, and California's list of regulated substances is broader than the federal RCRA list.

Before completing a commercial property purchase, buyers should conduct Phase I and potentially Phase II environmental due diligence, review any existing regulatory files, evaluate indemnification and representation provisions in the purchase agreement, and consult an environmental attorney about potential CERCLA, state Superfund, and underground storage tank liability. Environmental liability can significantly exceed the property's value.