Conclusions
The map accompanying this article indicates, by the lined areas, those parts of Stockport, Stuyvesant and Ghent that have the potential for landslides in Lake Albany clay.
A quick glance shows that the Towns of Stockport and Stuyvesant contain many slopes with slippage tendencies, a fact that the state and town highway departments will readily confirm. The area on Route 9 just south of the Columbiaville bridge had a long history of damage due to undermining by the clay soils. In 1976, that section of the road was rerouted, which required the moving of a house. "Test borings show the base of the new section of the road would be able to support the new stretch of highway without further landslide difficulty," the state Department of Transportation reported in 1976.
Portions of Route 9J have been constantly slipping, and Route 46 out of Newton Hook has ongoing problems.
Informed that Lang and Allendale roads were good examples of landslide difficulties, my drive there revealed that there was no longer a Lang Road. A short portion leads to a private driveway. Beyond, the road has slid into a deep, narrow valley and is closed to the public. The Stuyvesant highway department was at work on what is left of Allendale Road, and I was told of the problems there and on Hollow Road.
The rules for preventing landslides of Lake Albany clay are the same for highways as for buildings: do not add weight; do not excavate; and make sure the slopes do not become waterlogged because of poor drainage.
For the average homeowner or builder in an area of lake clay, certain precautions should be taken. Exploring carefully and thoroughly if lake clay is suspected would be the best maxim. The Columbia County Soil and Water Conservation Service office has soil maps and information that gives a property owner or prospective buyer a good idea of the makeup of the soil and whether deeper, more extensive test holes should be dug. Soil data and percolation tests are required from builders by the Columbia County Department of Health for a single-lot sewage disposal system or a subdivision review.
Planners should discourage or prohibit large developments on clay slopes. Insurance claims might be difficult to collect, for a slide is still considered to be an "act of God." The desire to build on hilltops with panoramic views should be tempered with the knowledge that Lake Albany clay requires special considerations. It can be done using California-type building techniques to anchor foundations.
Problems are most likely to surface in existing homes built on landslide-prone slopes. Extending the yard by adding fill is one way to precipitate a slide. Building anything that alters the drainage or increases the amount of rainwater running over the hill and infiltrating the soil adds to the potential. A prime example of a catastrophe-in-the-making would be an in-ground pool built on the edge of a hill. Follow this with a leak in the pool so that moisture is added to the soil and eventually the lake clay will move.
It would be well to remember that though the upper layers of Lake Albany clay appear to be brown and stable, underlying these are material that require only a little change in their natural equilibrium to make the clay unstable. For a fine view of an exposed hill of Lake Albany clay, drive into the road marked Dead End off the northeastern end of Mill Street in Hudson. An excavated hillside is visible on the left where the strata of gray and light brown clays are easily recognized.
COPYRIGHT 1988 MARGARET SCHRAMI followed Schram's advice and drove to the end of Mill Street. Then I walked halfway up the Dugway looking to the left for the excavated hillside she described. Either the hillside has been altered in the past thirty years by natural phenomena or the extensive excavation required when Charles Williams Park was created, or the hillside was simply covered with snow, but I could not see the strata.
Really interesting, Carole. It's pretty extensive. I'm surprised there haven't been even more problems.
ReplyDeleteIt's great to see these old maps. We also have data more recent than 1988, and higher-resolution maps of combined clays-and-slopes which the city's Conservation Advisory Council should have included in its nearly finalized Natural Resource Inventory. Although the public suggested including the recent data, it was ignored.
ReplyDeleteFor several years the CAC has received complaints about the serious and still-ignored erosion behind Crosswinds - and into Underhill Pond - but these complaints were also ignored.
Crosswinds illustrates the permanent threat of slope erosion at the city's margins, in this case combined with ill-planned "green infrastructure" for stormwater runoff. The city and state have a shared legal responsibility to see that annual inspections are conducted there (surely they aren't), but how can we even begin to diagnose a problem if the city refuses to acknowledge it exists?
Well now, there's your Conservation Advisory Council hard at work.
Which brings me back to the missing soil and slope maps in the CAC's new inventory. When I was told last year that any maps in the inventory had to be "off the shelf" and ready to publish, I responded that at least one such map is easily accessed. I received no further reply, which was consistent with years of being ignored about Crosswinds.
This year a previously stable slope behind Tanners Lane gave way. While you might think the CAC now feels a bit sheepish concerning its willful ignorance on the subject, it's more likely that the group feels self-assured and even revolutionary for its all-out commitment to the most radical sea-level rise predictions available.
The way I see it, in its "inventory" the CAC ignored useful local data on existing conditions - slope instability and existing erosion - to make as much room as possible for outlandish claims about as-yet-nonexistent future conditions.
After each of the "deadlines" announced by the CAC were challenged for their falsity, the motivation to finish the inventory became clear. A completed inventory is necessary before the Conservation Advisory Council can become the city's Conservation Board.
But the self-serving CAC has acted so irresponsibly towards the public (and nature!) that it should not become a Conservation Board. That should require a change of leadership, but also a change of the ugly culture that that leadership has fostered.
In my view, the largely uneducated CAC is an exploiter of nature for its own ends.