Trans-Pacific Engineering Corporation

representative projects

stormwater experience

Beginning on July 1, 2010, the Philadelphia Water Department began implementing the four-year phase-in of their new system for billing stormwater charges to commercial property owners in the City. The Philadelphia Water Department has developed a Stormwater Credit Program to qualify existing and/or newly proposed Stormwater Management Practices (SMP) to help reduce your stormwater fees.


Our Stormwater Management Experts can help you through the Credits Program.


  • Soils Investigations and Permeability Testing

  • Site Inspection and Surveys

  • Application Preparation

  • Stormwater Credits

    • Impervious Area

    • Gross Area

    • National Pollutant Discharge Elimination (NPDES)


  • Adjustment Appeals

  • Credit Renewals

  • Design of New SMP Facilities

    • Infiltration Trenches and Basins

    • Green Roofs

    • Porous Paving

    • Flow-through Planter Boxes

    • Rain Gardens

    • Capture and Reuse

TPEC can help you:


  • Analyze the storm runoff characteristics of your property (flow rate, runoff volume)

  • Verify your bill is calculated correctly

  • File appeals to correct property data

  • Determine your eligibility for stormwater credits

  • Evaluate potential cost-saving SMP facilities and the credits that can be gained from these facilities

  • Help you decide on a cost-effective solution that fits your budget

  • Help apply for low interest loans or grants toward stormwater management system installations or improvements

  • Prepare design plans, reports, and credit documentation forms and submit to PWD for review

  • Oversee construction of approved facilities

  • Inspect and certify the as-built condution for final approval by PWD

  • Inspect and re-certify installed SMPs for continuing credit from PWD


green city, clean waters

Several TPEC members work on-site at the PWD Office of
Watersheds and Public Affairs Unit helping to develop the Green City, Clean Waters plan for implementation, among a variety of other water resources-related initiatives.

Our staff is experienced in integrated watershed management, green stormwater infrastructure planning, hydraulic and hydrologic modeling, communications, planning, policy making, community outreach, coordination, and partnership development.

Tiffany Ledesma is on site at Ralph Brooks Park (Philadelphia) testing public art options that highlight green stormwater infrastructure. The results will inform a notification tool kit which will be employed by Philadelphia Water at its green stormwater infrastructure sites. The City of Philadelphia Mural Arts Program is also a partner on this project.

Abby Sullivan leads a green stormwater infrastructure tour at the Big Green Block in the Fishtown/Kensington section of Philadelphia.

Maggie Dunn is inspecting a new permeable driveway that was installed through Philadelphia Water's Rain Check program. Rain Check helps residents in Philadelphia pay for green stormwater infrastructure at their homes to manage stormwater and beautify their properties.

Maggie Allio Rwakazina, Paula Conolly, and Helaine Barr collaborate to review existing processes of the Philadelphia Water's Green City, Clean Waters program. Based on this analysis they will provide recommended policy solutions, risk mitigation strategies, and innovative process efficiencies for the implementation of the long-term green stormwater infrastructure program.

stormwater projects

Green Stormwater Infrastructure Systems - City of Philadelphia Water Department

TPEC is working with AECOM Water for implementation of its Green Stormwater Infrastructure (GSI) Systems. We are performing detailed geotechnical investigations and testing work to evaluate the subsurface conditions and soil characteristics that will support the city's design criteria.

LaSalle University

We are pleased to announce that Phase I construction of the LaSalle University Stormwater Management Incentive Program (SMIP) was recently completed at the southeast area of the campus. This involved the creation of two rain gardens to manage 6.7 acres of impervious surfaces. TPEC was the lead designer and assisted with construction oversight.

Rain Garden

LaSalle University
Philadelphia, PA

Stormwater Infiltration Basin

LaSalle University
Philadelphia, PA

We are currently working on Phase II design. This phase consists of managing 7.1 acres of impervious surfaces from the western part of the campus primarily through the use of underground filtration/detention systems. The purpose of this project is to significantly minimize the amount and/or flow of stormwater runoff entering the City of Philadelphia's sewer system by managing it on-site.

Stormwater Management and Design

TPEC is providing engineering design services to substantially reduce the stormwater fees for a solid waste management and recycling facility in North Philadelphia. A combination of site engineering, stormwater management, and construction of a green roof will be employed at the 13.2-acre site in order to qualify the property for stormwater credits with the Philadelphia Water Department.

Bioretention Pond

TPEC designed the bioretention basin for stormwater management at the Baxter Wastewater Treatment Plant.

Southeastern Waterway Restoration

Working with CDM, TPEC provided an interdisciplinary water resources team consisting of engineers, scientists, planners, and landscape architects to conduct water quality and ecological assessments, review stormwater management practices, and restore degraded stream channels and wetlands.

Pervious Pavement

TPEC completed parking lot design using pervious pavement at the Queen Lane Wastewater Treatment Plant.

Bus Shelter Green Roof

TPEC performed structural evaluation and design modification assistance for a bus shelter located in the City of Philadelphia. The project was part of the Bus Shelter Green Roof Pilot Project initiated by the Mayor's Office and the Philadelphia Department Office of Watersheds.

The Enterprise Center Green Roof

TPEC will perform the structural evaluation of the roof system at The Enterprise Center near 45th and Market Streets in the City of Philadelphia. Other features planned for the property include a geothermal heating and cooling system (which has been installed), and pervious pavement in the site's parking lot.

Tennyson Basin
Stormwater Infiltration Basin

Warminster Township
Warminster, PA

Gorson Drive Gabion Wall and
Stream Bank Restoration

Warminster Township
Warminster, PA

Stream Bank Restoration
8th and Greene Stormwater Improvements

Warminster Township
Warminster, PA