Principals

Richard A. Claytor, Jr., P.E. • President

Rich has more than 28 years of practical experience in civil and environmental engineering with specific expertise in water resource planning, design, implementation, research, education, and training. Rich has extensive experience and expertise in stormwater management design, implementation, program assessment, policy and evaluation. Rich also is experienced in watershed planning, training and education; water resource permitting and research; water supply and wastewater design; land use planning, site design and research; storm drainage, erosion/sediment control, roadway design; and construction administration. He has authored a variety of stormwater manuals and publications on stormwater policy, design and implementation, and presented at dozens of training workshops and conferences over the last two decades. He was the principal designer of stormwater management and stream restoration measures for a wide range of projects throughout New England and the Mid Atlantic.
| P: (508) 833-6600 x 107 | rclaytor@horsleywitten.com

Scott W. Horsley • Principal

Scott has 30 years of professional experience in the fields of watershed planning and water resources management. He has worked as a consultant to federal, state, and local jurisdictions, and private industry throughout the United States, Central America, the Caribbean, the Pacific Islands, and China. Scott has been an innovator in the environmental profession, and thrives on bringing new and fresh approaches to challenging projects. Scott has a strong understanding of the full range of technical, planning, and policy issues associated with land use and environmental science. Scott has served as an instructor for a nationwide series of U.S. Environmental Protection Agency (EPA) workshops on groundwater protection and coastal resources management. He has also served on numerous advisory boards to the EPA, the National Academy of Public Administration, Massachusetts Department of Environmental Protection (DEP), Massachusetts Executive Office of Energy and Environmental Affairs (EEA), National Groundwater Association, and Massachusetts Audubon Society. Scott has received national (EPA) and local awards (Mashpee Conservation Commission) for his work in the wetlands and stormwater management fields. He has taught numerous seminars in water resource protection, and is an Adjunct Professor at Tufts University where he teaches courses in water resources policy and low impact development (LID).
| P: (508) 833.6600 x 127 | shorsley@horsleywitten.com

Mark Nelson, P.G., L.S.P • Principal – Senior Hydrogeologist

Mark is a Senior Hydrologist and is responsible for the firm’s Water Resource, Wastewater Planning, and Site Assessment and Remediation projects. Mark has more than 25 years of experience in groundwater modeling, surface water modeling, hydrogeologic investigations, and fate and transport analysis of contaminants in soil, sediments, and groundwater. Mark has direct experience in the regulatory and permitting requirements associated with wastewater projects, and has been successful in securing numerous Groundwater Discharge Permits with the Massachusetts Department of Environmental Protection (DEP). He currently serves as the Program Manager for HW’s $17 million contract with U.S. Environmental Protection Agency (EPA) Office of Ground Water and Drinking Water, providing technical advice on source water protection, water security and the Underground Injection Control Program. He is also the Program Manager for the firm’s $22 Million contract with EPA’s Office of Science and Technology. Mark is a Licensed Site Professional (LSP), authorized by the Commonwealth of Massachusetts to direct the assessment and remediation of contaminated sites. Mark has been an instructor for the EPA teaching workshops on wastewater planning, water security, ground water and surface water hydrology, Low Impact Design (LID) contaminant transport, estuarine and ground water modeling and wellhead and source water protection. He has also qualified as an expert witness in Massachusetts and Wisconsin.
| P: (508) 833-6600 x 128 |  mnelson@horsleywitten.com

Joseph Longo • Principal – Senior Engineer

Joe is a Senior Engineer with 17 years of professional experience focused on hazardous waste site assessment and remediation as well as civil site design development projects for public and private clients. Joe’s permitting, design, and construction administration experience ranges from oil and hazardous materials assessment and remediation, to water supply and wastewater treatment plants, civil / site design, as well as permitting at the town, state (MEPA), and federal (NEPA) levels. Joe has directed small to large scale project teams internal to HW and those involving subconsultants including architects, MEP’s, land surveyors, commissioning agents, wetland and rare species scientists, among others; as well as coordinating and directing projects through public and private bidding, bid evaluation, contractor selection, and construction administration.
| P:(508) 833-6600 x 125 | jlongo@horsleywitten.com

Nathan Kelly, AICP, NCI • Principal Planner

Nate is a Senior Planner and directs the firm’s Providence, Rhode Island Office. Nate has more than 10 years of experience, and has provided professional planning, zoning and facilitation services to more than 30 New England municipalities. His work ranges from comprehensive zoning revision projects to the development of affordable housing, open space, rural land preservation and economic development studies. Many of his projects include extensive public outreach in the form of charrettes, public forums, community work sessions, and public hearings. Nate is a member of the Rhode Island and Massachusetts Chapters of the American Planning Association and serves on Grow Smart Rhode Island’s Advisory Council. He is one of the primary authors of the Massachusetts Smart Growth/Smart Energy Toolkit, a lead facilitator for the Rhode Island KeepSpace program, and his work in Rhode Island has received three awards from the state APA Chapter. Nate received his Masters Degree in Urban and Environmental Policy from Tufts University and currently resides in Providence, RI.
| P:(401) 272-1717 | nkelly@horsleywitten.com

Thomas Noble • Senior Project Manager – Principal

Tom is a Senior Project Manager with 20 years of professional experience assisting government agencies and private clients in complying with the Bioterrorism Act, the Safe Drinking Water Act, the Clean Water Act, Superfund legislation, and both state and local environmental laws and regulations. His main areas of expertise include water security and emergency response training, project management and permitting, hydrologic investigations in support of wastewater treatment facilities, water resource impact analyses, groundwater modeling, technical review, and knowledge transfer.

Currently, Tom serves as the HW’s water security lead, assisting the U.S. EPA Water Security Division, states, and local governments to better prepare for, respond to, and recover from water and wastewater system disasters, both natural and man-made. He is also a veteran of the armed services, having served as an engineer officer in the U.S. Army.
| P:(508) 833-6600 x 115 | tnoble@horsleywitten.com