Septic Installation & Cesspool Conversion in Glenwood

We install septic systems and convert cesspools in Glenwood, the stretch of Highway 11 between Mountain View and Volcano, about 25 minutes from our equipment yard in Keaau. Glenwood is small and doesn’t have its own census count. What sets it apart for septic work is the rain. It’s one of the wettest places we work.

Glenwood Basics

  • Part of the Mountain View CDP. The Census doesn’t count Glenwood separately; its residents fall inside the Mountain View CDP, which had 4,215 people in 1,428 households in 2020. Fern Forest lies about 2 miles to the southeast.
  • About 2,300 feet up. That’s well above Mountain View village and well below Volcano.
  • More than 200 inches of rain a year. The University of Hawaii Rainfall Atlas shows the Glenwood area at roughly 205 to 220 inches a year, close to double what Volcano Village gets.
  • On the highway. Highway 11 runs through Kurtistown, Mountain View, Glenwood and Volcano Village on its way to the national park. The county’s Glenwood Park and the Glenwood Recycling and Transfer Station are both here.
  • Lava zone 3 on the south side of the highway. USGS places the developed areas on the south side of Highway 11 between Keaau and Volcano in lava hazard zone 3, a lower-risk zone farther from active vents.

A Short History on the Old Railroad Line

Glenwood was the end of the line for the Hilo railroad’s Volcano branch. In 1901, a branch was built 12.5 miles up the mountain from Olaa to Glenwood, and visitors rode the train to Glenwood and then took buses the last 9 miles to the Volcano House. The railroad cut the branch back to Mountain View in 1926 and abandoned the line from Olaa to Glenwood in 1938. Today it’s a quiet rural area with homes on wooded lots on both sides of the highway.

Septic Design in Very Wet Ground

At this elevation on the windward side of Mauna Loa, NRCS describes soils formed in weathered volcanic ash over pahoehoe or aa lava. One example is the Ohia series, which has its reference site near Mountain View and occurs between 1,200 and 3,000 feet where rainfall runs 137 to 177 inches. It’s typically 40 to more than 60 inches deep to lava, well drained, but with moderately slow permeability in the soil and very slow permeability in the rock below. We haven’t confirmed the exact soil on every Glenwood lot, and some lots will be shallower or rockier. The engineer’s soil profile settles it.

Put that together with 200-plus inches of rain and a few things stand out:

  • Slow soil means a bigger field. Where the percolation test comes back slow, the engineer sizes the leach field larger to handle the same daily flow.
  • Groundwater separation gets checked closely. HAR 11-62 requires at least 3 feet between the bottom of the disposal area and groundwater. In this much rain, the engineer looks hard for signs of a seasonal high water table.
  • Shallow lava means soil replacement. If the profile hits fractured lava, the rule calls for a soil replacement system.
  • Water management around the field. Roof runoff and driveway drainage need to be routed away from the leach field.

Wet-weather scheduling is part of the job, too. We’d rather wait a few days for the ground to firm up than tear up a lot with an excavator.

What Glenwood Owners Typically Need

  • Converting an older cesspool. Homes built before the 2016 cesspool ban may still have one, and Act 125 sets January 1, 2050 as the cutoff for all of them. Our step-by-step conversion guide shows the process.
  • New homes on wooded lots. A new house needs an approved system, and the county won’t sign off the building permit until DOH has reviewed it.
  • Additions. Extra bedrooms on a permit can lead DOH to ask for an upgrade, and the rules count a room as small as 70 square feet as a bedroom.

For water, plan on catchment unless you know otherwise. Even the county’s Glenwood Park runs its restrooms off a 3,000-gallon storage tank. Tell the engineer where your catchment tank and lines are so the septic layout stays clear of them.

Rules and Funding

Glenwood is not in one of the five Hawaii Island priority areas from the 2017 DOH report, but the 2050 deadline still applies. Check your parcel on the UH Cesspool Prioritization Tool, and ask the county Department of Environmental Management if you have questions about sewer. USDA Section 504 repair loans and grants may help very-low-income rural owners, so check eligibility with the USDA office in Hilo. Our grants and loans page has the current list.

Along Highway 11

Planning a Glenwood Project

Tell us roughly where you are along the highway, how the driveway looks, and if the job is a cesspool replacement or a new build. Request a free estimate

Frequently Asked Questions

Is Glenwood its own town for census purposes?

No. Glenwood is counted as part of the Mountain View CDP.

How does Glenwood’s rain affect a septic system?

At more than 200 inches a year, the main concerns are groundwater separation and slow-draining soil. Both can mean a larger leach field or a different system type.

Will my Glenwood lot need a soil replacement system?

Only if the soil profile hits fractured lava within the depth the system needs. Many lots at this elevation have ash soil over the rock, but depth varies.

Can you work in Glenwood during the rainy season?

Yes, but we schedule around saturated ground. Digging in mud can damage the field area.

What lava zone is Glenwood in?

USGS places the developed areas on the south side of Highway 11 between Keaau and Volcano in zone 3. For a lot north of the highway, check the county’s lava zone map for your parcel.