Residential & Commercial
IWS Design
An Individual Wastewater System (IWS) is Hawaii's engineering term for an on-site septic or aerobic treatment unit. All new construction and significant improvements require a PE-designed IWS permitted through the State DOH Wastewater Branch under HAR Chapter 11-62.
- Initial site visit and feasibility assessment
- Soil investigation and percolation test supervision
- System type selection: anaerobic, aerobic, or alternative
- Complete PE-stamped engineered design plans and specifications
- DOH Wastewater Branch application submittal and review management
- Response to all DOH reviewer comments and re-submittals
When is an IWS required? Any new construction, bedroom addition, or significant renovation on a property not served by county sewer requires a new or modified DOH-approved IWS. Consult Matthew early in your planning, as IWS design timelines can affect overall project schedules.
Cesspool Conversion to IWS
Hawaii Act 125 (2017), HRS §342D-72, requires every cesspool in the State of Hawaii to be upgraded by January 1, 2050. With over 88,000 cesspools statewide discharging millions of gallons of untreated waste daily, this is one of Hawaii's most critical environmental priorities.
- Complete cesspool assessment and system evaluation
- IWS type selection appropriate for your site and soil
- Full DOH Wastewater Branch permitting
- Contractor selection guidance and coordination
- Construction oversight to ensure design compliance
- Final DOH certification and Approval to Use letter
My family and friends drink from the same aquifer yours does. Converting your cesspool is one of the most meaningful things a Kona property owner can do for this community, for the reefs we all love, and for the generations who will depend on this water long after we're gone. Note: conversion is also required sooner than 2050 if you are adding bedrooms, applying for new permits, or are within 200 feet of a water body.
Percolation Test
Supervision
A percolation test (perc test) measures how quickly water drains through your soil, a required data point for every IWS design. Under HAR Chapter 11-62, Appendix C, perc tests must be performed under the supervision of a licensed PE or registered engineer and documented on the DOH-approved form.
- Scheduling and coordination with property owner and contractor
- Test hole preparation and saturation per HAR requirements
- Perc rate measurement and documentation
- DOH Percolation Test Report (Form D) preparation
- Integration into IWS design sizing calculations
Construction Inspection
& Final Certification
After your IWS is constructed, the DOH requires a licensed engineer to inspect the installation and certify that it was built in accordance with the approved design plans. Matthew conducts the inspection, prepares the required documentation, and submits everything to DOH to obtain your Approval to Use letter.
- On-site construction inspection at critical stages
- IWS Construction Inspection Report preparation
- Contractor Certification Form coordination
- DOH final submittal and approval tracking
- Delivery of Approval to Use letter to property owner
Matthew also provides stand-alone construction inspection services for projects designed by other engineers, or for existing IWS systems requiring inspection for a property transfer.
