Greenland NH – Large koi Pond

Greenland, NH Koi Pond & Stream Installation

From a DIY Pond Project to a Custom Backyard Koi Pond

This Greenland, NH homeowner originally set out to build his koi pond himself. After getting into the excavation and realizing the size, complexity, and amount of detail involved, he decided the project was more than he wanted to take on alone. That’s where New England Ponds & Patios came in.

The finished project is a 25′ × 15′ koi pond approximately 3 feet deep, featuring a dedicated fish cave, intake skimming bay, wetland filtration, and a 25-foot natural stream with a custom bridge crossing.

This was far more than simply digging a hole and installing a liner. A pond of this size and complexity requires careful planning, proper liner protection, water management, rock placement, filtration design, and experience working with challenging excavation conditions.

Challenging Soil Conditions Required Extra Protection

One of the biggest challenges we encountered was the soil. The excavation conditions were not ideal for installing a liner directly over the prepared subgrade, so we took additional measures to protect the pond system.

We installed two layers of heavy-duty underlayment beneath the 45-mil EPDM liner, providing additional protection against the difficult soil conditions. We also placed a thin layer of sand across the pond bottom and on each of the pond shelves to create another protective buffer between the excavation and the liner.

When building a long-lasting koi pond, protecting the liner is critical. Once the pond is filled and the rockwork is installed, accessing the liner to correct a problem becomes extremely difficult. Taking additional precautions during construction is well worth it.

Rain Turned Excavation Into Another Challenge

The project was also hit with persistent rainy weather. An unlined pond excavation can quickly turn into a muddy mess when exposed to repeated rainfall, potentially washing out shelves, damaging the shape of the excavation, and creating additional problems for the liner installation.

To protect the excavation, we used large tarps throughout construction to keep the rain out and preserve the carefully prepared pond shape.

Despite the difficult weather and soil conditions, we continued working through the challenges and kept the project moving forward.

A Pond Designed for Both Beauty and Function

The finished pond incorporates several components that work together as one system.

The intake skimming bay helps remove surface debris before it enters the pond’s filtration system, while the wetland filter provides biological filtration and becomes an important visual feature of the overall landscape.

The 25-foot stream creates movement and sound as water travels back toward the main pond. A bridge crossing adds another layer of interest and gives the homeowner a unique way to interact with the pond and surrounding landscape.

The pond’s depth and dedicated fish cave also provide a suitable environment for koi, while the extensive rockwork helps make the pond look like a natural part of the property rather than a constructed feature.

Experience Matters on a Project Like This

Large koi ponds with streams, bridges, filtration systems, and extensive natural rockwork are not simple installations. Every component has to work together—from the excavation and liner protection to water flow, filtration, rock placement, and finishing details.

This project required approximately three weeks of construction, including working through challenging soil and weather conditions.

The goal wasn’t simply to finish the pond. It was to build something that would look natural, function properly, and exceed the homeowner’s expectations.

In the end, that’s exactly what we accomplished.

“Mike installed a large pond in my backyard. It was a 3 week project and the thought and process put in on the project was amazing. The process behind the placing of rocks, laying of the bridge and intricate detail involved was amazing to watch. Mike was a true professional and whenever I came outside to take a look he was always there to answer questions, explain the next steps etc… I would highly recommend this company. Very hard workers and cleaned up afterwards. Started on the day he said he would and finished on time!“

— Gary.