Side lane renovation (1) - drainage

Side land has been on my list since 2022.

I break down the project into follownig sub-tasks

• Lower the soil height
• Retaining wall
• Install surface drainage and connect to stormwater system
• Foundation waterproofing
• Paving
• Planting

Site condition

“In March 2022, coinciding with Sydney’s rare rainy season, we discovered water seepage in the garage foundation shortly after moving into our new home. Initial investigation revealed that the pathway outside the wall was higher than the garage foundation, and because our neighbor’s property was at a higher elevation than ours, water would flow onto this path during heavy rains, causing the soil to frequently become saturated.

From then on, this pathway became undesirable. Firstly, due to insufficient sunlight, weeds often grew there. Secondly, it was frequently damp and not very clean.

In March 2023, we upgraded our water heater, replacing the original tank-type with an instantaneous water heater to free up the limited space in this lane.

Remove soil

In October 2023, while pouring concrete in the front yard, we had an excavator lower the side path by 100mm, removing a total of 3 tons of soil. This brought the level of the side path down to be even with the garage floor, solving the problem of the buried foundation. The next step was to improve drainage.

After that, we were busy with building the decking and didn’t continue with the renovation of the side path. The exposed soil was again overgrown with weeds after a few months. In June 2024, when my father-in-law came to visit, he manually dug out some of the soil, which prompted us to formally plan the renovation of the side path.”

Hand digging

After the excavator’s work, we chose to manual digging due to the potentials of disruption to underground services. While digging down 100mm in one area, we encountered several sandstone rocks, and the soil was primarily composed of clay. During the excavation process, we used crowbars to remove the rocks and transported the clay to an empty space on the other side.

As we continued digging, we discovered a large gap at the bottom of a section of the fence. This might be one of the reasons for water flow. We considered it necessary to add a retaining wall to address this issue."

Reroute the pipe

During the excavation process, we discovered the main water supply pipe. After lowering the soil level, there was very little soil left above the pipe. To avoid the risk of damage to the pipe from future paving and potential machinery use, we decided to relocate this section of the water pipe to the wall, eliminating future concerns.

Retaining walls

After considering several options of retaining wall solution, we decided to use steel post and treated pine to construct the wall as it’s the most cost-effective solution.

Add drainage

The drainage channel was constructed with a slope of 1:100. With existing paved surfaces at both ends of this 11-meter long path, the natural 60mm drop was insufficient for proper drainage. We dug the channel for the drainage pipe according to the required ratio.

To connect the drainage pipe to the existing stormwater system, I rented a concrete saw from Kennards Hire for $260 per day. A quick check revealed that Hilti is actually a high-end brand. The rental company provided four batteries, using two at a time, and with a garden hose connected, we were ready to cut. It took less than an hour to cut open the ground. After digging out the soil around the PVC pipe, we discovered that the existing adapter was cracked. I replaced it with a Y-shaped double connector and also the stormwater pipe connection. It then took a day to connect the drainage pipe to the double connector.

Waterproof foundation

Paving

More details on paving in second part