Category Archives: Energy efficiency

Water Woes on Drumlins

What is a drumlin anyway?  A gremlin with an aptitude for percussion?   Seriously, a rounded, elongated hill in the Connecticut landscape is probably a “drumlin”. The best known is Horsebarn Hill on the eastern side of the UConn campus at Storrs. Landing Hill in East Haddam was  in the local limelight several years ago. Lately I’ve been working on Meetinghouse Hill and Misery Hill in Franklin.  The Goshen Wildlife Management Area is another. The word “drumlin” comes from Ireland, where this land form also occurs.

The core of a drumlin hill is fine-textured, compact glacial debris, though bedrock may be underneath, poking through in a few places.   The compact “hardpan” layer (in common parlance)  may be over 100 feet thick, and dates from the prior Illinoisan glaciation (over 128,000 thousand years ago). Only the top layer, usually just a few feet deep, is sandier, looser soil, formed from the melting ice masses of the more recent Wisconsin glaciation, underlain by the compact till (scientists’ terminology).

These soils are seasonally wet.  Though the level summits seem, at first glance, to be well-suited to community development, they are challenging to develop, whether on drumlins or elsewhere, such as plastered onto the sides of traprock ridges. Most gently sloping drumlin hilltops in New England used to be productive hayfields, growing lushly in spring when soil moisture was available, going dormant in mid summer.  Pockets of wet meadow were rich in flowers, like New England Aster. Drumlin fields make fine hunting territories for raptors like barred owl.

Colorful wet meadow perched on top of drumlin.

Multiple seasonal seepage wetlands and headwaters streams flow down drumlin hillsides. They are a valuable source of clean water for the drainage basin if the drumlin is undeveloped, they but may become conduits for construction runoff.

There is more groundwater discharge on the nearly level sections of drumlin hillsides than on the steep sections. These are also prone to septic breakout.

Only a small percentage of Connecticut’s soils are compact tills but a disproportionate share of construction site fiascos and problem-plagued new subdivisions occur on hardpan soils. Wet, silty, sticky  hardpan  soils, on drumlins and also in other landscape settings,  can become a mire for heavy construction equipment because the snowmelt and spring rains “perch” on top of the hardpan. Saturated silty soils are highly erosive,  often an erosion control nightmare. Flooding problems are more severe than on absorbent soils, and water pollution from lawns and septic systems becomes a problem at lower home densities.  Break-out from home septic systems happens more often.

Typical complaints of drumlin residents: wet and moldy basements, icy sidewalks;  soggy, fungus-infested grass, burned-out grass, and dying shade trees; extended sump pump operation (not energy efficient), mosquitoes, and septic odors; and polluted down-gradient ponds.  These all become more of an issue for seasonally wet, drumlin soils, because more water stays at the surface, as it cannot soak into dense hardpan soil. (Runoff coefficients are higher, in engineering jargon.)

With careful home and septic system placement, curtain drains, and appropriate landscaping, one can avoid some of these problems – but only if home densities are relatively low.

Ironically, the loose upper soil layer of a drumlin is usually so shallow that it holds little reserve water during dry spells, so drumlin lawns need much irrigation in summer, though excess water is the problem in other seasons.   Solutions: small lawns, partially wooded yards, and/or a meadow landscape with drought-tolerant grasses like Little Blue Stem, a.k.a. Poverty Grass.

A Plea for Guidance

Could  CTDEEP and our Conservation Districts provide land use boards, planners, and developers  with more guidance on drumlins’  multiple constraints?  On-line mapping (Web Soil Survey or WSS) available from the Natural Resource Conservation Service (NRCS) does show the approximate locations of seasonally wet, hardpan soil units, like the Paxton, Woodbridge, and Wethersfield soil series.

More guidance is needed to make sure fertilizers and pesticides are not applied before or after heavy rains.  This happens all the time in Connecticut suburbs!  Turf chemicals tend to run off drumlin soils, more than off more absorbent soil types, especially when the soils are already soggy.

Few understand that watercourse setbacks often need to be wider and  septic system densities need to be lower on compact till soils, to protect down gradient wells, headwaters streams, pools, and lakes from excessive nitrogen,  in nitrogen enriched groundwater and runoff. Because they reduce lot yields, these constraints need  explanation in an official DEEP guidance document, preferably also in a  CT Health Department memorandum!

Clear-cutting may seem to be  more economical for the developer, who should be warned that this is not wise on a drumlin!  To minimize future “water woes”,   maximize  remaining tree cover when subdivisions are built. The reason is two-fold: 1) to slow the velocity of the falling rain, and 2) because trees spew thousands of gallons of water into the air as water vapor (transpiration), helping dry out those surface soils.  After clear-cutting, a drumlin hillside that used to be wet only in March and April may stay wet to the surface though June – and before long, one will see the tell-tale mottles and grayish matrix color of a jurisdictional Connecticut wetland soil.

Some, but not all engineers use underdrains and clay stops  to prevent frost heave damage to roads and utility pipes, and to allow shallow groundwater to continue to seep down slope to wetlands that depend on this water source – instead of being shunted along  roadbeds and sewer lines.  Guidance is also needed in this area.

Once aware of drumlins’ constraints and resources, town  zoning boards  will be able to  guide development more appropriately,  protecting valuable vernal pools and hillside streams, and at least a portion of the productive forests. For expansive overgrown fields on flat-topped drumlins, if the alternatives of farmland or grassland wildlife habitat are not possible, at least the damage to down-gradient headwaters resources,  from a  low density, large-lot residential community, with small lawns,  will be  much less than from a large, dense subdivision.

(First version of blog posted on 9-6-08)

Ailing from Indoor Air Pollution? Go Outside!

This afternoon I heard on public radio (Faith Middleton Show) that  health problems from indoor air pollution are worst in the most energy efficient, air-tight homes (LEED- certified).  I also heard that on average Americans spend less than 95% of their waking day indoors. The Yale PHD interviewed praised his own leaky windows, for the healthy outdoor air they let into his house. (Research was done by Environment and Human Health, Inc. )

This is a very real problem, a major contributor to childhood asthma.  I have heard that it can be addressed without squandering energy by systems of ventilation that include heat exchangers – and by choosing building and decorating materials for minimal off-gassing- like wool rugs – or straw mats, rather than synthetic carpet with backings and  adhesives that generate unhealthy gasses.  It would be great for sustainable farmers to have a stronger market for sheep wool! Faith Middleton pointed out that better labeling of materials is needed, so that homeowners and contractors can make informed choices.

If structural changes are not possible in the short term, it helps to periodically open multiple windows to air the house, on warmer days in winter, and to spend more time outdoors.  My mother did not give me and my siblings a choice; we were sent outside to play and did indeed find interesting things to do.   A diverse natural environment with some wildlife, insect life, and wildflowers will hold your childrens’ interest longer!  Obviously we  breath fresh air while hiking and walking the dog.

Consider also that time spent working in the yard, is time breathing healthier air- typically also with less dust and mold spores than indoor air.  Pulling out lawn weeds, trimming bushes and raking weeds by hand is more time consuming than using power -tools.  It seems to me that the yard would be more inviting to many adults, with greater variety of plantings – and self-seeded plants –  native and non-native,  to keep track of and tend. My husband is not a trained horticulturalist or ecologist, but enjoys spending time outside with me, following my lead, and listening and learning as I point things out.  He now is able to recognize and mow around attractive native perennials – like buttercups and daisies – that crop up in the lawn, even before they bloom!

The outdoors is also more welcoming in summer,  if indoor and outdoor temperatures are similar. At our house in Cheshire, Connecticut, in lieu of air conditioning,  we use airflow drafts though open windows and screened doors, and  shade from an “umbrella” catalpa tree (pruned each fall) on the south side of the house.  Our extended family’s vacation house on Long Island is shaded to the south by two large hemlocks.  It has a long, narrow shape with many windows on both sides, allowing  for excellent cross ventilition. A screened second floor sleeping porch sleeps up to five (on cots) and is a pleasant place to spend time (read, sleep, or just rest and listen to the birds outside)  even in very hot, humid summer weather,  typical of Long Island.

Tomorrow, June 12th,  is the birthday of my brother, who believes lots of  work and play outdoors is the key to good health. We’ll be touring three demonstration alternative “organic” lawns in Newton, Massachusetts (Ecological Landscaping Assoc., one with a solar house.   I expect to learn more ways to spend time outside on my piece of land, and have a fine-looking, dog-safe and wildlife-friendly, “organically ”  landscaped property – fodder for a future blog post. One way I know from childhood is to welcome black locust trees* and clover, which take nitrogen out of the air, by means of symbiotic rhizobium bacteria – free fertilizer! See photo below.

Sleeping porch: comfortable on hot LI nights- and days- in a pre-airconditioning house

*Black locust is on the invasive species lists of some states. It can spread aggressively, fertilize, and change,  sandy infertile natural habitats, as on the Cape in Massachusetts, but in a home landscape , in a pasture, or as a street tree, it is just fine, in my opinion (and that of other Long Island “natural resource professionals” and farmers).  Its abundant nectar is valuable for bees. Black locust  is in fact native to the US –  is from further south and west than Long Island and southern New England.