Soil Testing: The Foundation of Successful Septic Tank Installation on Long Island

When it comes to septic tank installation on Long Island, proper soil testing isn’t just a regulatory requirement—it’s the key to ensuring your system functions efficiently for decades to come. When installing a septic system in New York State, site evaluation plays a crucial role. This evaluation ensures that the system will function properly, protect groundwater, and adhere to environmental regulations.

Understanding New York State’s Soil Testing Requirements

Under Section 18-38(b)(5) of the Watershed Regulations, a minimum of one percolation test and one deep soils test are required in the primary area and one percolation test and one deep soils test are required in the reserve area for all SSTSs. For Long Island property owners, this means that before any septic installation can begin, comprehensive soil testing must be completed to determine if your property can support a septic system.

At least two percolation tests shall be made at the site of each proposed sewage treatment system. These tests are critical because A percolation test is only an indicator of soil permeability and must be consistent with the soil classification of the site as determined from the test holes.

The Percolation Test Process

The percolation test, commonly called a “perc test,” measures how quickly water drains through your soil. This test measures the rate at which water drains through the soil. Your perc test results indicate the soil’s ability to handle effluent from the septic system.

The testing process involves several steps. Presoak the test holes by periodically filling the hole with water and allowing the water to seep away. This procedure should be performed for at least four hours and should begin one day before the test (except in clean coarse sand and gravel). After presoaking, Pour clean water into the hole, with as little splashing as possible, to a depth of six inches above the bottom of the test hole. Observe and record the time in minutes required for the water to drop from the six-inch depth to the five-inch depth.

Interpreting Soil Test Results

Understanding your soil test results is crucial for system design. A rate of 60 minutes per inch (MPI), meaning the water dropped one inch in 60 minutes, is often the cutoff point for a standard gravity-flow septic system, although the maximum number varies from 30 to 120 MPI depending on local regulations. However, soil that drains too quickly can also be problematic. The cutoff for too-fast percolation is typically 1 to 3 minutes per inch. Below that, water absorbs too fast to be effectively treated before reaching the groundwater.

Fast-percolating soils may need an alternative system design, as they can allow contaminants to reach groundwater quickly. Conversely, slow-percolating soils might require a larger drain field. This is why if different results are obtained for multiple holes in a proposed absorption area, the slowest stabilized rate shall be used for system design.

Deep Soil Testing Requirements

Beyond percolation testing, deep soil evaluation is equally important. For intermediate-sized septic systems, DEC recommends generally that deep test pits should be 6-8 feet deep to enable observation of the soil at least 5 feet below the bottom of the proposed system or to ground water. soil tests must be a minimum of 72″ from the original surface elevation unless a boundary condition is reached at a shallower depth.

These deep tests help identify critical factors such as The soil profile and the presence and depth, or absence, of soil mottling (generally an indication of seasonally high groundwater level). Review of general color and colored mottling should be done using Munsell color charts in natural light only.

Long Island’s Unique Soil Conditions

Note that parts of Long Island do use seepage pits due the nature of construction, soil conditions and known hydrogeology. General Waivers were issued to Suffolk and Nassau Counties allowing certain alternative systems. On Long Island, OWTS are prevalent due to limited sewer system coverage, leading Suffolk County to establish regulatory codes addressing safety and environmental concerns.

Long Island’s sandy soils often present unique challenges and opportunities for septic system design. In general, soils with high sand and gravel content drain the best and soils with a high clay content or solid rock are the worst.

Working with Professional Testing Services

Persons with training/experience in conducting such tests should conduct percolation tests. They include but are not limited to design professionals, surveyors, sanitarians, soil scientists, geologists, technicians, WPA inspectors and system installers. The health department requires testing in the form of soil test pits and/or percolation tests witnessed by a representative of the health department’s Engineering Staff.

When you need professional Septic Tank Installation Services Long Island, it’s essential to work with experienced contractors who understand local soil conditions and testing requirements. Quality Cesspool has been family-owned and operated for four generations, delivering dependable cesspool and septic system services that homeowners and businesses rely on. Our history is built on trust, and we strive to uphold this legacy with every job.

Planning for System Design

Once the required infiltration area is determined by daily flow, percolation tests and soil evaluation, the required useable area of the property for subsurface treatment can be found. An additional useable area of 50 percent shall be set aside for future expansion or replacement whenever possible. This means your property needs sufficient space not only for the initial system but also for future replacement needs.

The soil tests must be done in the location of the drain field. You cannot simply relocate your system without additional testing and approval from local authorities.

Ensuring Compliance and Success

Proper percolation testing is a necessary step for determining the design and feasibility of your septic system, to ensure long-term functionality and compliance with environmental standards. The type of septic system for your home depends on a variety of factors, such as lot size, ground slope, soil conditions, size of the home/occupancy, local/state regulations, and your budget.

For Long Island property owners, understanding soil testing requirements is the first step toward a successful septic installation. At Quality Cesspool, our process is designed for efficiency and excellence. First, we’ll perform a comprehensive site assessment to determine your unique needs. Next, we’ll develop a customized plan that will meet the specific needs of your property. We understand the specific challenges that come with Long Island’s soil conditions and local regulations. As a local business, Quality Cesspool has built our reputation on reliable service and honest communication.

By investing in proper soil testing upfront, you’ll ensure your septic system operates efficiently, protects groundwater, and meets all regulatory requirements—saving you time, money, and headaches in the long run.