Rock Crushing Ban for Overlook Acres Project - Yes or No?
As the Public Hearing for Overlook Acres draws to an end, the city Planning Department is drafting conditions to be discussed, edited, and voted on by the Planning Board. The ultimate decision on conditions for the project rests entirely with the Planning Board, as does the approval or rejection of the project.
At the October 1, 2020 Planning Board meeting, the developer was asked to pull all buildings and roads out of the 100 foot wetlands buffer area. They have informed the city that they will have a final design ready by Thursday October 8, which is the due date for projects appearing before the Planning Board on October 15. In addition, the draft conditions for the project will be available publicly by Thursday, in case the board goes forward with a vote, and in case the vote is in favor of the project. Public comment for the project on October 15 can include comment on the new layout, the project in general, and specific comments about the draft conditions.
As I mentioned several weeks ago, a ban on rock crushing is now a standard condition for Planning Board approvals. This will remain a standard condition until the city adopts a rock crushing ordinance. The developers have stated that banning rock crushing for this project will add time, expense and environmental impact.
I spoke with the developer and explained that the ban on rock crushing came from the same neighborhood in which this project is proposed. These same neighbors, citing noise complaints and health concerns from rock crushing at the Woodlands Subdivision project, lobbied hard to ban rock crushing, as did I. And this, in fact, will be the first large project to possibly be approved by the Planning Board and have this condition included in the approval. I am strongly in favor of banning rock crushing, but since the developer felt they had a case for allowing it, that the result would be added time for site preparation, added blasting and increased traffic, I asked them to make their case to me and to the neighborhood.
They replied with the following:
Pursuant to our recent conversation about no onsite crushing impacts - if we are unable to process and recycle material onsite under ‘normal sitework operations’ – in addition to significant economical impacts, we see the direct earthwork impacts as follows:
OVERALL DURATION - The total sitework preparation to subgrade, under ‘normal’ conditions, is estimated as a 6 to 8 month duration. Without onsite processing, the same duration would easily become 18 to 24 months given the expanded scope of drilling, splitting, hammering, blasting, and the net import/export effects noted below. If hours are limited, the 6 to 8 month duration may expand as well.
DRILLING/BLASTING - Drilling would be more than twice the ‘normal’ duration as rock would need to be split and blasted at half the size. Even then, blasted natural material will require hammering to ‘transportation’ size material. It is more far more efficient to blast larger rock sizes, hammer them onsite, and immediately process.
EXPORT - Without onsite rock processing - trucking export would be 2.5x – 3x the number of export truck trip because of the sheer volume of larger material demands more space in the truck. This equates to what would be 1,000+/- export truck trips becoming 2,500 to 3,000 export loads of material exported for offsite processing.
IMPORT - Once the material is exported it will need to be processed, loaded and delivered back to the site. This is estimated at roughly 2,000 additional truck trips of importing. At 20 trips per day average, that’s about 100 working days additional time on the schedule. Using 20 working days per month, this equates to 4 to 5 months more trucking of material on the schedule.
ENVIRONMENTAL – Diesel vehicles contribute substantially to emissions that are ozone precursors and to airborne particulate matter. If natural rock weighs 2,600lbs per cubic yard and each export truck can haul 20cy of uncrushed rock (30cy capacity but wasted for rock voids), each truck would weigh 52,000lbs loaded or 26 US tons. If each truck goes 15 miles one-way emitting 200 carbon dioxide grams per ton-mile, this would mean 78,000 grams of CO2 per one-way trip or 0.086 US tons of emissions per one-way loaded truck trip. The estimated surplus truck loads of 3,500 to 4,000 loaded trips would then equate to ballpark 300 to 350 net US tons of carbon dioxide emissions. This analysis does not account for the unloaded truck trips in or out or the additional offsite material management to handle the rock twice as the rock processing would still need to occur offsite. The order of magnitude impact due to “no onsite processing” is minimally/ballparked to 400 to 500 tons or around 80,000lbs to 100,000lbs of excess carbon emissions that would be emitted into the environment unnecessarily.
In addition, the developer sent information about a new rock crusher, which creates less noise and dust. He offered that use of this type of crusher could be included as a condition. He sent video of the rock crusher in action, so that everyone can judge for themselves. They also offered to place the crusher in a remote location, away from abutters, to lessen the noise. And they pointed out that since the site is lower than surrounding neighbors, the sound would be less. [I do not have expertise in this type of work, though I question the lessened noise because the site is lower.]
From the developer:
In researching construction managers, vendors/subs, and equipment – I may have a mutual solution to the rock crushing. One of our construction managers is using this machine in Worcester. It’s worth noting that the back-up warning beeps are required by OSHA to be louder than the equipment which is why the dB reading jumps when loaders are backing up. This machine also handles dust containment. Here’s the video: https://youtu.be/baeZmPOn2Z0
Here is the manufacturers video on their rock crusher: https://youtu.be/cbi3zwOysOc
I am asking each of you to review this information, watch the videos, and let me know your thoughts. There is a trade-off if rock crushing is not allowed, and I want each of you to have all of the information, and not learn later that schedules are impacted because rock crushing is disallowed. I do question some of the trade-offs though, as I am sure truck trips can eventually be made more efficient by dropping off large rock and returning to the site with a load of processed rock. But I am not a construction expert.
Please feel free to send me an email (pmorsillo@salem.com) with your thoughts, or call me directly (978) 317-4697.
Again, I don’t know if the Planning Board will be making a final decision on October 15, this is just in preparation of that event if it happens.
