Skip to content


The ARRO brand of civil engineering is rooted in our love of our profession, our dedication to our clients, and our desire to improve the environment and the communities we serve.

Long before PA DEP implemented its Municipal Separate Storm Sewer Systems (MS4) Program, ARRO assisted its municipal clients in addressing their stormwater problems.

ARRO has always taken a holistic approach to stormwater management in an effort to mimic the pre-disturbance hydrologic conditions. Local drainage patterns, soils, geology and vegetation land cover play an important role in the development of any successful stormwater project. ARRO has a proven history of developing innovative new development and remedial stormwater designs, best management practices (BMPs) and retrofit strategies, green infrastructure, as well as floodplain and stream restoration projects. In addition to stormwater management design, ARRO is well-versed in floodplain and stormwater ordinance development, implementation, and enforcement.

Implementation of the MS4 Program has dramatically changed over the last several years. A municipality can no longer assume it is compliant without having established a long-term program goal and multiple short-term objectives to achieve that goal. Implementation of the six Minimum Control Measures, as outlined in the MS4 Permit, provides the outline for how the MS4 Program is developed; however, the Minimum Control Measures content needs to be location specific and address localized issues.

ARRO can assist municipalities in defining MS4 Program objectives and goals and implementing procedures to maintain a compliant MS4 Program. ARRO has participated in and successfully navigated our clients through EPA MS4 Program audits and PA DEP MS4 Program reviews. These experiences, coupled with our in-depth understanding of the MS4 Permit requirements, allow ARRO to develop and oversee multiple successful MS4 Programs and provide technical oversight to municipalities that wish to manage the program themselves.

Stormwater/MS4 Services

ARRO is also a leader in MS4 compliance, providing MS4 consulting services for municipal clients across seven counties and two states. MS4 consulting services include the following:

ARRO’s approach to support compliance and fulfill permit requirements includes: