Storm Drain Relocation & Stormwater Management Project in Malvern, PA

Project Snapshot

Field	Project Details
Location	Malvern, PA – Tredyffrin Township, Chester County
Project Type	Storm Drain Relocation & Stormwater Management
Completion Date	January 2022
Client	Private Homeowner
Storm Drain Relocated	Approximately 200 linear feet
Primary Storm Pipe	18-inch HDPE
Engineering Required	Yes
Municipal Coordination	Tredyffrin Township

Construction Story

Project Overview

A planned residential addition could not move forward because an existing township storm sewer crossed directly through the proposed building footprint.

ES Excavation worked with the project engineer and Tredyffrin Township representatives to complete the required storm drain relocation and stormwater improvements. The project included excavating and removing sections of the existing storm sewer, relocating approximately 200 linear feet of drainage piping, installing new 18-inch HDPE storm pipe, reconnecting existing drainage structures, constructing an engineered underground stormwater management system, and restoring the disturbed areas of the property.

The work required careful layout, controlled excavation, coordination with the approved engineering plans, and protection of the surrounding residence, landscaping, utilities, and township drainage infrastructure.

1. Existing Site Conditions

The existing township drainage system crossed the residential property and passed directly through the area designated for the planned addition. The existing inlet and underground storm sewer had to remain functional while a new route and stormwater system were prepared.

Because the work involved township drainage infrastructure on an occupied residential property, the project required an organized excavation plan and close attention to the existing home, landscaping, access areas, and surrounding utilities.

1. Existing Site Conditions

2. Survey and Layout

Before excavation began, the proposed storm sewer alignment, connection points, building limits, elevations, and underground improvements were located in accordance with the approved engineering plans.

Accurate field layout was essential because the relocated storm drain had to avoid the proposed addition while maintaining the elevations and drainage flow required for the township system.

3. Existing Storm Sewer Excavation

ES Excavation carefully exposed the existing storm sewer to confirm its location, depth, condition, and connection points.

The excavation was completed within a confined residential work area while maintaining access around the property and limiting unnecessary disturbance outside the approved construction limits.

3. Existing Storm Sewer Excavation

ES Excavation carefully exposed the existing storm sewer to confirm its location, depth, condition, and connection points.

The excavation was completed within a confined residential work area while maintaining access around the property and limiting unnecessary disturbance outside the approved construction limits.

4. Existing Storm Sewer Removal

Sections of the existing concrete storm sewer were disconnected and removed from the proposed building area.

The abandoned pipe sections were cleared from the excavation so the new storm drain alignment could be constructed outside the footprint of the planned addition

5. Storm Drain Relocation

A new trench was excavated along the engineered route for the relocated township storm sewer.

The trench alignment and elevations were carefully maintained so the new drainage system would reconnect properly with the existing infrastructure and provide continuous stormwater flow around the proposed addition.

5. Storm Drain Relocation

A new trench was excavated along the engineered route for the relocated township storm sewer.

6. 18-Inch HDPE Storm Pipe Installation

Approximately 200 linear feet of 18-inch HDPE storm pipe was installed along the new drainage alignment.

The pipe was set to the required line and grade and connected to the existing stormwater structures. HDPE pipe provided a durable underground drainage route while allowing the original storm sewer to be removed from the proposed building footprint.

7. Stormwater Management System Installation

The project also included the installation of an engineered underground stormwater infiltration system.

The system was constructed using the specified excavation, geotextile fabric, clean stone, underground piping, and inspection or cleanout connections shown in the approved design. The completed system was intended to manage runoff generated by the residential improvements while remaining below the finished grade.

7. Stormwater Management System Installation

The project also included the installation of an engineered underground stormwater infiltration system.

8. Site Restoration and Final Grading

After the underground drainage work was completed, the excavated areas were backfilled and the site was graded to restore positive surface drainage.

The final grading prepared the property for lawn restoration and the next phase of residential construction while leaving the relocated storm sewer and stormwater system protected below grade.

9. Completed Project

The completed work removed the existing township storm sewer from the proposed addition footprint and established a new engineered drainage route around the planned construction area.

The project also provided the required underground stormwater management improvements and restored the property to a stable, graded condition for the next phase of development.

9. Completed Project

The completed work removed the existing township storm sewer from the proposed addition footprint and established a new engineered drainage route around the planned construction area.

The project also provided the required underground stormwater management improvements and restored the property to a stable, graded condition for the next phase of development.

Project Results

Approximately 200 linear feet of relocated township storm sewer
New 18-inch HDPE storm drainage piping
Reconnection to existing drainage infrastructure
An engineered underground stormwater infiltration system
Removal of the storm sewer conflict from the proposed addition footprint
Final grading and site restoration
A site prepared for the next phase of residential construction

Completed Project Gallery

Services Demonstrated

Frequently Asked Questions

Why did the existing storm sewer need to be relocated?

The existing township storm sewer crossed directly through the proposed footprint of a residential addition. Relocating the pipe allowed the planned construction to proceed without building over or interfering with the township drainage system.

Does storm sewer relocation require engineering?

Projects involving municipal drainage infrastructure generally require engineered plans, elevations, connection details, and approval from the applicable municipality or authority. This project was completed in coordination with the project engineer and Tredyffrin Township.

What type of pipe was installed?

Approximately 200 linear feet of 18-inch HDPE storm pipe was installed along the new engineered drainage route.

What is an underground stormwater infiltration system?

An underground infiltration system temporarily stores stormwater runoff within a stone and piping system below grade. The system allows water to be managed on the property while preserving the usable surface area above it.

Can ES Excavation work from engineered stormwater plans?

Yes. ES Excavation performs excavation and installation work from approved engineering plans for stormwater systems, storm drain relocation, drainage improvements, grading, utility excavation, and residential site development.

Does ES Excavation coordinate with builders, engineers, and architects?

Yes. ES Excavation works with homeowners, builders, engineers, architects, and municipal representatives to complete excavation and stormwater work in accordance with the approved project requirements.

Planning a Stormwater or Drainage Project?

ES Excavation works with homeowners, builders, engineers, and architects on stormwater management systems, storm sewer relocation, drainage improvements, site grading, utility excavation, and residential site-development projects.

Contact ES Excavation to discuss the excavation and underground drainage requirements for your project in Malvern or the surrounding areas of Chester, Delaware, and Montgomery counties.