Frequently Asked Questions
Your Environmental Consulting Questions Answered
We understand environmental assessments, reports and approvals can feel overwhelming. Below you’ll find answers to the questions we’re most often asked by property owners, developers, and building professionals. You can jump straight to FAQs on Onsite Sewage Management Design, Contaminated Land and Site Investigations and Soil and Water Testing.
Onsite Sewage Management
Why do I need an onsite sewage management assessment report?
Local councils require prior approval before any onsite sewage management system is operated, installed or altered. To grant that approval, councils need an assessment report prepared by a qualified professional.
A compliant report ensures your system is safe, suitable for your land and meets all relevant guidelines. Whether you’re planning a new build, renovating, or buying a rural property, we make sure you have the right documentation to move forward with confidence.
What's included in an onsite sewage management assessment?
Our assessments are designed to be thorough, practical, and easy to understand. A typical report includes:
- Site inspection of your property and any existing system
- Discussion about your project goals, property usage, and future plans
- Soil testing to determine soil type, drainage and constraints
- Measurement of slope, rainfall, and distances to waterways, bores, and wells
- Recommendations for system type, upgrades, or new installations
- Calculations for system sizing and the optimal disposal area location
Our goal is to give you a clear picture of what’s required and why, so you can make informed decisions.
Can HMC do a pre-purchase assessment of a septic system?
Absolutely. Pre-purchase sewage assessments are one of the most important steps when buying a rural property and are a big part of what we do.
We inspect the existing system for compliance, condition, and functionality, then recommend any necessary maintenance, upgrades, or replacement work. Our detailed report allows your plumber to quote accurately and can often help you negotiate a fair purchase price before settlement.
What should I do if my septic system is failing?
Signs of septic system failure can include pooling water, bad odours, gurgling pipes or slow drainage.
Because local government laws require council approval before any repair or replacement work can be carried out, the first step is to get a professional assessment. Give us a call – we’ll identify the cause, recommend solutions, and help you navigate the approvals process.
What if I receive a defect notice or letter of action from council?
Don’t panic, this is more common than you think.
Give us a call, and we’ll go over the notice with you, explain what the council is asking for, and outline the steps to resolve the issue and get back into compliance.
Contaminated Land and Site Investigations
Why do I need an underslab soil contamination investigation?
If you’re demolishing a home with a concrete slab that was built between the late 1940s and June 1995, there’s a chance termite chemicals were applied to the soil before the concrete was poured. Many of those historical chemicals (such as DDT, dieldrin, aldrin, and chlordane) are persistent in soil.
An underslab investigation identifies whether residual chemicals are present, so you can manage them safely, meet council requirements and avoid delays during demolition or redevelopment.
How does HMC collect underslab soil samples?
We make the process as minimally invasive and efficient as possible. Typical steps:
- We cut approximately four holes (80mm diameter) in the concrete floor slab to access the soil beneath.
- Use a hand auger to collect soil samples at three depths through each hole: 0-150mm, 150-300mm, and 300-500mm.
- Once sampling is complete, each borehole is backfilled with clean sand, and the concrete core is replaced.
- Samples are sent to a NATA-accredited laboratory for analysis.
We’ll explain the process before we arrive and leave the site tidy.
What happens if the results show contamination?
If the laboratory results show residual contamination, the options available will depend on the chemical concentration and the site constraints:
- Onsite re-interment (managed and verified) if levels and conditions allow; or
- Removal and disposal to an approved facility (if required); or
- Engineered Containment or other remedial techniques for certain situations.
We’ll prepare a Remedial Action Plan (RAP) outlining the recommended approach and submit it to the council for approval. Once remediation is completed, we provide validation reporting to confirm the site is suitable for its intended use.
Why do I need a contaminated land investigation?
State and local governments have strict guidelines for investigating contaminated land to protect public health and the environment. If your property has a history of potentially contaminating activities or if you’re proposing a land-use change, the council will require a contaminated land investigation report as part of your development application.
A proper investigation demonstrates that the site has been adequately assessed, any risks have been identified, and the property is safe for its intended use.
If you’re unsure whether your property is affected, we can do an initial review to advise next steps.
What are potentially contaminating activities?
Potentially contaminating activities are any past or present land uses that could create risks to human health or the environment. These might include:
- Agricultural pesticide use (cropping, orchards, and banana growing)
- Sheds or structures that stored fuel or chemicals
- Workshops, metal fabrication, radiator repairs, or dry cleaning businesses
- Waste storage or disposal areas (including fill and spoil piles)
- Underground or above-ground fuel tanks
- Farm dumps or burn sites
- Asbestos or lead in older structures
- Off-site sources (e.g., migration from neighbouring service stations)
If you’re unsure, we can help you assess the situation.
If you’re unsure whether an activity on or near your site is relevant, we can review historical records and aerial imagery and help you assess the situation.
How does HMC carry out a contaminated land investigation?
We follow a phased approach that’s thorough, systematic, and tailored to your site:
Phase 1 Preliminary Site Investigation (PSI)
We review site history, past and present land uses, aerial imagery, and council records, as well as conduct a site walkover to identify potential contamination risks.
Phase 2 Detailed Site Investigation (DSI)
If the PSI indicates potential contamination, we conduct soil and/or water sampling. This may include installing groundwater monitoring wells.
Phase 3 Remedial Action Plan (RAP)
If contamination is found, we prepare a plan outlining options to treat, contain, or remove contaminated material for council approval.
Phase 4 Validation Reporting
Once remediation is complete, we validate, through additional soil testing, that the site has been properly treated and is safe for the proposed land use.
Throughout the process, we keep you informed and ensure you meet all regulatory requirements.
Soil and Water Testing
Does HMC test soil and water samples?
Yes, we collect soil and water samples on-site, and while we don’t perform laboratory testing ourselves, we work with NATA-registered laboratories in Tweed, Lismore, Brisbane, and Sydney. This ensures you get accurate, reliable, and independently verified results that councils and regulators trust.
We handle the entire process for you, from collection to interpretation of results.
Still Have Questions?
We’re here to help. Whether you’re a homeowner planning a rural build, a developer managing a large project, or a professional referrer needing reliable environmental consulting support, we’re ready to answer your questions and guide you through the process.
Call us today or email us to discuss your project and how we can help you move forward with confidence.