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Aaron S. Mapes


  • University of Maryland School of Law (J.D., concentration in Environmental Law, 2011)
  • University of Pittsburgh (B.S. in Business and Economics, Dean's List, 2007)

Bar Memberships

  • Pennsylvania, 2011


  • Pennsylvania Bar Association
  • Philadelphia Bar Association
  • Co-Counselor, Delaware Valley Environmental Inn of Court

Aaron S. Mapes



(215) 587-1005

(215) 320-4144 Fax

Aaron S. Mapes is a Principal in the Firm's Environmental Practice Group. He counsels clients on a wide-variety of environmental matters, including environmental diligence for real estate transactions and energy infrastructure projects, brownfields redevelopment, compliance with environmental laws, environmental permitting, and litigation of complex environmental lawsuits and administrative appeals. Mr. Mapes’ clients include real estate private equity funds, local municipalities, and companies in the energy distribution and industrial sectors.

In 2019, Mr. Mapes was selected by his peers as a Pennsylvania Super Lawyer Rising Star in the category of Environmental Litigation. For information about this selection and an overview of common third-party publications, rankings, and lists methodologies, click here.   

Prior to joining Post & Schell, Mr. Mapes served in the Environmental & Toxic Tort group of a large, regional law firm, where he focused primarily on litigation associated with underground storage tank releases and exposure to asbestos-containing products. He is a graduate of the University of Maryland School of Law with a concentration in Environmental Law. During law school, he was president of a student group that provided legal assistance to communities affected by Hurricane Katrina and completed clerkships at the U.S. Environmental Protection Agency’s Headquarters and Region 3 offices.

Transactional Practice

Mr. Mapes’ transactional practice focuses on the acquisition, financing, and selling of real estate. He has experience managing and advising clients on all environmental aspects of real estate transactions, including selecting and retaining qualified environmental consultants; advising on environmental investigation and remediation scopes and strategies; reviewing and commenting on technical reports; working with clients, lenders, and consultants to comply with lender protocols; negotiating favorable provisions in purchase and sale agreements, loan agreements, and environmental indemnities; negotiating with insurance companies to obtain broad coverage in environmental insurance policies; and analyzing and assessing environmental risk and available risk management options. 

Mr. Mapes regularly works on single- and multi-property transactions in gateway markets across the United States (US), as well as transactions involving large portfolios of properties located in multiple states. He also has significant experience counseling clients on international real estate transactions, particularly in the United Kingdom (UK), Germany, and France.      

Mr. Mapes’ transactional practice also includes environmental diligence for oil and gas distribution, electrical power generation, and other large-scale industrial projects.  In this capacity he coordinates and evaluates a broad array of environmental studies, including assessments of wetland and stream crossings, threatened and endangered species, historic and cultural resources, noise and visual impacts, hazardous materials usage, and air emissions. Mr. Mapes has notable experience in evaluating wetland delineations, classifications, and mitigation plans, having served as counsel in a federal lawsuit involving a wetland delineation dispute and a high-profile administrative appeal alleging improper and insufficient wetland delineation, classification, and impact mitigation.     


Mr. Mapes routinely assists clients with issues arising during brownfields redevelopment and building renovations, working with clients to navigate complex regulatory schemes and develop cost-effective remediation, abatement, and waste management strategies. He also assists clients in obtaining environmental permits, pursuing environmental insurance claims, completing environmental audits, and negotiating administrative penalties.

Litigation Practice

Mr. Mapes defends environmental claims brought by third parties and brings and defends administrative appeals related to environmental agency determinations. He has practiced in state, federal, and administrative courts, and is skilled at taking and defending depositions, drafting complex motions and briefs, conducting efficient legal research, and assisting with trials and trial preparation.