Slump Blocks Fear Mongering or Real?


According to the DEP, Atlantic Highlands & Highlands have a long recorded history of slumping that goes back hundreds of years and continues to this day. “Most of the older slumps were probably caused by under cutting from Atlantic Ocean wave action during a time when Raritan Bay was open to the ocean hundreds of years ago” (Minard,1974). One of these slumps occurred in 1782, making it the earliest recorded landslide in New Jersey. There have been other smaller landslides in this area during the last 100 years.

Let’s look at some of them, shall we?

 1. Eastpointeslump1

Construction of the Eastpointe tower in the mid-1970s, despite public warnings against the construction from USGS, triggered faults in soil blocks and produced actual movement on the hill that required a major change in the County owned road known as Ocean Boulevard, which at the time ran in front of Eastpointe. It was forever closed to through traffic, and what had been a 40-foot wide road was reduced to a sixteen foot access road. Further the County was forced to buy & demolished four houses — one at the top, one in the middle and two nearer the bottom of the slope leading down from the Scenic Overlook park. Clearing away these structures allowed the County to institute uniform measures to protect soils and vegetation, eliminate impervious cover, and close off public access on the steep slope there.

 2. South Linden

slump 2January 1999, a “wall of mud, rocks and vegetation”  20 feet long & 5 ft wide slammed down into the Highland Shores condominium complex on Shore Drive 100 feet below the hilltop, the residents of eight condo town houses on Shore Drive had to be evacuated because the hillside was found to be “unstable and at risk of another collapse,” The town engineer at the time was quoted as saying “It was a slope failure….Anyone can see that that area has subsided.”

slump 33. Shore Drive

April 2007, a nor’easter and torrential rain fall triggered a landslide between Linden Avenue & Shore Drive.

4. Shore Drive

August 2011, Hurricane Irene triggered a slide from the townhouses off Lindenslump4 Avenue down to the town homes below at 319 Shore Drive. A total of 3 of the Hillside Town homes had mud, two others had other minor damage like losing their A/C units.  Units 319 A&B had the worst damage.  319 B had actual structural damage towards the rear of the building.

11 thoughts on “Slump Blocks Fear Mongering or Real?

  1. rockemsockem

    I was recently up at Mt. Mitchill overlook and there is actually a educational plaque with illustrations regarding slump block. If you look it up in the internet here is description:
    Long Description:
    Mt. Mitchill, at an elevation of 266 ft above sea level, is the highest natural point on the Atlantic Seaboard between southern Maine and the Yucatan Peninsula of Mexicoo. Cartographers named the prominence, located in the southwest corner of the park, in honor of Dr. Samuel Latham Mitchill (1764-1831), A New York physician, naturalist, educator, and U.S. Congressman. Mitchill was part of an 1816 expedition to measure the height of the Navesink Highlands. Mt. Mitchill and the surrounding highlands are prone to slumping or slump blocking. When this geologic phenomenon occurs, large blocks of earth, typically sandy soil covered by an erosion-resistant capstone layer of ironstone, slide suddenly down a cliff face.

    I don’t know there must be a lot of fear mongers making this stuff up. If we are prone to it don’t mess with Mother Nature I think she already proved herself to be a worthy opponent. Nuff said!

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  2. Duncan McLeod

    By this logic, shouldnt there be restrictions on having construction or residences at the bottom of the hills in the area? According to the premise of this topic and the supporting information provided, the slumping phenomena has been going on for hundreds of years. If that is so, then this happened without and regardless or any structures, because they were not there at that time.

    IE it doesnt matter what is built on the hills or not built as the hills will “slump”, mudslide, or otherwise come tumbling down. Basically lending creedance to the old saying that **** goes downhill.

    So, if the slumping is a natural process that regularly happens in the area, shouldnt all residences and structures at the base of the hill be declared dangerous of habitation and be demolished as a hazard to public safety? If the slumping is a natural process that has happened for hundreds of years as contended here, then it is only a matter of time, no matter what is built on the hill, until the hill collapses on everyone living below?

    in short you cant have it both ways. If the information provided here is indeed true, then building either on the hill, or at its base is totally unwise. That being said, is there any way to really stop the so called sloping process?

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    1. highlandsblog Post author

      What above isn’t true? Are you denying any of the instances occurred or what exactly are you inferring isn’t factual?

      Why don’t you think there are houses where the Henry Hudson Trail is between Highlands and AH? That nobody just never bothered developing it?

      On Bayside, why do you think there are houses on one side of the street and not the hill side?

      In short we *can’t* stop the natural occurrences but we can slow down the man made ones i.e. how/where we do build, not taking down trees on the hill etc.

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    2. NoLongerNew

      Duncan, yes, there should be restrictions on what’s built below the hill. Unfortunately what’s done is done. I have to confirm, but I’m pretty sure a Highlands lifer that knew of the slope issues was on the zoning board that approved the variances and allowed Hillside Village to be built.

      I’m sure the town would have done something after Irene if it were for the loss of those precious rateables. I know at least one or two unit owners have filed successful tax appeals. The town is lucky that not everyone filed one.

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  3. Stacy

    Risk vs Reward. Does the risk of the slump block shifting outweigh some imaginary reward (or one that nobody seems able to prove exists)? I don’t know many people who would want that risk on their conscious because nobody can guarantee there would not be a shift regardless of the engineering. I hope that for my fellow home owner’s who live near and below that property that they don’t wind up paying the price for someone’s selfish agenda.

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  4. Duncan McLeod

    Highlands Blog,

    Im not impying that any information that you posted here is not accurate. In fact, the opposite it true and Im sure it is. I have witnessed some of the events that you have described.

    My point is that the people that dont want development above them on the hill of course dont want the hill coming down on them which is completely understandable. My point is will stopping any development on the hill prevent this from happenening. With the information you have provided here, regardless of building and development the hill has a history of slumping, mudslides etc. So, the danger of these things happening exists no matter what.

    I also want to point out that whether or not buildings on the hill cause this to happen, or happen with greater frequency is questionable. In the event you described in 1999, even though the language was that the collapse was a “slope failure”, I believe no one nor anything was blamed for it happening other than the forces of nature.

    So in the end the conclusion in the end has to be that maybe halting development on the hill might help the situation with the hill, but will not prevent it from happening in the future.

    So, if there is going to be a push to halt any building on the hill due to danger to life and limb of those living below, then there should be an equal push to halt development at the bas of the hill etc.

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    1. NoLongerNew

      So how far from the base of the hill do you propose we halt development? I think the areas in danger are already developed making the Shadow Lawn high-rise that much more of a concern. If there is an area slated for development that could be in danger, I’m all for supporting the halt on developing a reasonable distance from the base.

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    2. rockemsockem

      If you read the plaque at Mt Mitchell one of it’s purpose is to stabilize hill by planting mature trees with deep roots to help any further slump. If they chose to develop there it should be least amount of strain to hill and slumping and they should plant mature trees around that will further help to stabilize. Whether you are uphill or downhill it doesn’t matter it just can’t be ignored. My personal observation the recent slides have happened directly under developments(Eastpoint,Hilltop) so why risk a possible catastrophe that will not only place town back into stone ages but might actually injure or kill people. Just don’t see logic in that if we can come up with alternatives that will work.

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    3. rockemsockem

      Beyond mapping these zones, Minard’s USGS report recommended actions to avoid triggering slump blocking. The report calls for “careful thought, planning, investigations, tests, and analyses” before construction in this entire “area of geological hazards.” Precautions should include “avoidance of the removal of material from the toes of possibly critical slopes, prevention of excessive water infiltration in the ground in critical areas, and avoidance. of excessive loading on upper surfaces in these areas” (Minard 1974, page 23).
      http://www.ahnj.com/ahnj/Departments/Environmental%20Commission/Green%20Sheets/Slump%20Blocks/

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  5. Dingus

    Nice job on reporting the facts. Opinions are a dime a dozen, facts hope to educate and refine people’s opinions; with the ultimate goal of creating informed and producive opinions, that lead to actions. Not just more of the same, poor, poor, pitable us.

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  6. Twisted

    Re: the 1999 incident at S. Linden/Shore Dr. @ Highland Shores Condos: I’m a current resident of Highland Shores, but wasn’t one at the time of the incident. Since the initial construction of Highland Shores around 1990 there was always a retaining wall at the base of the hill (since the mudslide it has been greatly improved with a regrading and a top barrier). Nevertheless, according to anecdotes I’ve heard from long time locals, this event was caused by a blocked water drainage system that was not properly maintained. As the pressure from downward drainage built up over time, the pipe burst causing the incline to collapse. It is true that the hill/cliff is prone to collapse, but improper and poorly maintained systems contribute to this tendency. In addition to the threat of tidal surges, the biggest problem in Highlands is the downward surge of rain water from hills. Without a proper drainage system in place there’s just no where else for the rain water to go but down.

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