November 10, 2025 Planning Board Special Meeting - WEHI Transcript

on the lower slopes. So10 the excavation has to be dewatered at all times.11 We recommend, because there are concerns from the12 residents that, that, there would be slope movement, so13 we recommend that the, that the monitoring program14 include the installation of what's called, slope15 indicators. These are tools that will, that if the16 slope moves the tubes go through a curvature and you17 could tell if the slope, if and when the slope is18 beginning to move or it has moved and it would be a19 benefit, I think, to the applicant if he has a long-term20 record during the construction as to whether there is or21 never was any slope movement. It would be to his22 benefit to consider doing that.23 We think that groundwater monitoring wells should24 be installed because it's very difficult to determine25

5 of 28 sheets Page 17 to 20 of 112 01/05/2026 03:19:18 PM 17 where the actual groundwater level is in the bedrock.1 There could, in this case, be at least two groundwater2 levels. There would be a groundwater level on the3 interior of the site where the wetlands exist currently4 and that could be due a first condition on the bedrock5 which is likely to be permeable. The sandstone, which6 underlies the soft bedrock at depth, have not been7 determined, that is considered an aquifer and so water8 does occur and it can move through it. So that, we9 think that the groundwater monitoring wells should be10 put there so that we could determine -- so the applicant11 could demonstrate that whatever mitigating measures are12 applied to the stormwater infiltration system, which we13 recommend that the applicants engineer address that as14 part of the approval process.15 And then the final grading should strictly be16 performed to ensure that the runoff is intercepted and17 prevented from running off over the slope.18 And that was pretty much a summary of what we are19 recommending that they, that, I don't know who's20 empowered to apply these requirements, but these are21 requirements that we think should be incorporated in the22 approvals.23 CHAIRMAN BAGOFF: Is there anything in the24 recommendation that should be done before the board25 18 continues its approval process?1 THE WITNESS: Well, I think the, the, the2 review of the infiltration basin concept and whether the3 mounding would effect, that should be done. It's4 possible -- it would be beneficial to install wells to5 actually determine what the groundwater level is. I6 would suggest maybe in the vicinity of Langan's borings,7 I think it's two and four, which are about -- they're8 two and four apparently appear to have been performed9 beyond the basalt formation and they're in the area that10 was identified in the hazard report that was produced by11 the --12 CHAIRMAN BAGOFF: So Princeton Hydro did13 four borings and they came up with mottling and Langan14 did 100 and came up with nothing. In your opinion --15 THE WITNESS: I'm not aware that Princeton16 did any borings.17 MS. McGOVERN: They were off-site.18 CHAIRMAN BAGOFF: They were off-site.19 Around the exterior of the site.20 THE WITNESS: Okay. I'm sorry, we didn't --21 I didn't pick that up in the report. If I missed it, we22 can go back and check that,

RMAN BAGOFF: They were off-site.19 Around the exterior of the site.20 THE WITNESS: Okay. I'm sorry, we didn't --21 I didn't pick that up in the report. If I missed it, we22 can go back and check that, but I didn't see any23 exploration actually done by them.24 CHAIRMAN BAGOFF: Is it possible to have an25 19 area like this where -- well, let me ask you a question.1 As an expert, do you think that there's groundwater2 infiltration in this area?3 THE WITNESS: I think there's some and4 whether it would develop a, it would be, develop a fully5 submerged condition so that pressures build up. The6 other problem you have with jointed bedrock is that the7 joints, for instance there's bedrock let's say at8 elevation 600 near the top of the slope or even higher,9 and sometimes in bedrock there will be faults or open10 joints and what happens if water opens -- enters the11 joint in a higher elevation and there's a continuous12 supply of water, that acts kind of as a short circuit13 down slope and so that, that joint fills up all the way14 down the slope and so a point down the slope is15 suddenly, or there would be a build up so that point16 down the slope is feeling a water pressure that could be17 equivalent to 20 or 30 feet of slope because of the18 amount of topography and that could be enough to19 initiate a slope failure problem and that's kind of20 things that do show up in heavy rainfall events.21 CHAIRMAN BAGOFF: Would you expect to see22 mottling somewhere in borings on this mountain?23 THE WITNESS: The, the report, if there was24 groundwater present it's likely that you would see, you25 20 would see mottling. Mottling. The, the -- Langan1 specifically states that they did not see, they looked2 for it and, they say they looked for it and they didn't3 see it. Both of their engineers used a, what's a4 general engineering color classification in their5 descriptions of conditions. Princeton Hydro indicates6 that the DEP regulations requires what's called a7 Munsell Color Chart, which involves, you have to take a8 really careful look at the colors and different shades9 mean different things in the mottling. The rocks don't10 indicate that any of that was noted and I think it's11 Langan's contention that it wasn't present.12 CHAIRMAN BAGOFF: Is mottling important to13 know if you're building a site?14 THE WITNESS: Mottling is a phenomenon that15 occur's where there

hink it's11 Langan's contention that it wasn't present.12 CHAIRMAN BAGOFF: Is mottling important to13 know if you're building a site?14 THE WITNESS: Mottling is a phenomenon that15 occur's where there is a persistent water level and16 usually the water level varies over the season and it17 rises -- it's usually the water levels are a maximum18 around the end of March and April, because the trees are19 still dormant or about to be, about to start drawing20 water. But before they enter that state there's nothing21 drawing ground water out of the ground because the22 vegetation is not active and so that represents the23 highest water level that would occur in the year and so24 if you're doing test pits in any specific time and you25

01/05/2026 03:19:18 PM Page 21 to 24 of 112 6 of 28 sheets 21 do notice mottling, the mottling, the elevation that1 mottling occur's would define the groundwater level that2 would be assumed to be the seasonal high water table.3 CHAIRMAN BAGOFF: Would that be important to4 your calculations or your estimation of safety?5 THE WITNESS: That would -- you would6 ordinarily assume water levels that would be at the7 seasonal high water table in your stability analysis.8 Now, in their, in the contact with us after reading this9 report Langan indicates that they do have stability10 cases that address that. We haven't seen them yet.11 CHAIRMAN BAGOFF: So there's more things for12 you, there are more things for you to see to make a more13 accurate opinion, is that correct?14 THE WITNESS: That's correct.15 CHAIRMAN BAGOFF: Okay. Okay.16 Mayor McCartney.17 MAYOR McCARTNEY: Thank you, Mr. Kleinberg.18 THE WITNESS: Yes, ma'am.19 MAYOR McCARTNEY: Thank you. I do have20 questions, but first I want to say thank you for your21 analysis of this and in your delivery because I actually22 understood everything that you said. I do have23 questions, but it was explained very nicely. Thank you24 very much.25 22 Just go back to the beginning a little bit.1 Where you mentioned in the Langan report the bedrock or2 the basalt, that the sanitary sewer that runs between3 the basalt and the sandstone.4 THE WITNESS: I'm sorry.5 MAYOR McCARTNEY: That the sanitary sewer6 runs the between the basalt and sandstone.7 THE WITNESS: Oh, what I said is that it8 appears that there is a, what happens, what happened is9 it was originally only sandstone here and then Jurassic10 -- this volcanic material came through and pushed the11 sandstone apart, and so what we're looking at with the12 basalt is right where the basalt ended when the volcanic13 flow ended. So there's sandstone underneath it and if14 you go father to the west there would be sandstone over15 it and then you have this same cycle repeating in the --16 this is the second Watchung Mountain. At the first17 Watchung Mountain where there are some slope problems,18 that's a second intrusion of the basalt and then there's19 sandstone to the east of that.20 MAYOR McCARTNEY: It seems to me what you're21 saying they're avoiding basalt, so you would not want to22 disturb the basalt?23 THE WITNESS: What -- well, it may have been24 that sandstone is

f that.20 MAYOR McCARTNEY: It seems to me what you're21 saying they're avoiding basalt, so you would not want to22 disturb the basalt?23 THE WITNESS: What -- well, it may have been24 that sandstone is much easier to excavate than the25 23 basalt and that may have been the reason for the1 location of the easement at that location, but we didn't2 review the plans for the, the sewer, the existing sewer.3 MAYOR McCARTNEY: I had a question about,4 you referred to 1.7 as a safety and that would be5 adequate. So on the scale or rating where is 1.76 adequate?7 THE WITNESS: Okay. 1.7 is a result that8 Princeton Hydro, just to be clear, was a value for a9 slope failure surface that passed through the bedrock10 and then low value safety factor of 1.7. And the way11 the safety factor is defined, you have a, a lot of the12 failure surface is shown as a circle and so what the13 driving force is, is the weight inside the circle, the14 resisting forces, the sheer resistance along the15 circumference of the circle and so 1.7 means that the16 material has about 70 percent more strength than would17 be required to prevent, to just reach equilibrium at the18 slope. So that means that, and they used a very, a GSI,19 Geological Strength Index, that was very low. It's for20 a very poor, poor quality rock and even when they did21 that for that particular failure surface it still had 7022 percent more strength than was required. The convention23 as for -- well, I think it's even referred to in the24 Corps of Engineers Manual for ordinary slopes. In other25 24 words, where you're not putting a dam or a founding a1 large retaining wall on rock and that sort of thing, the2 convention is that 1.5 would be the safety factor. And3 those 50 percent more strength than you need.4 MAYOR McCARTNEY: So is more or less on5 that, if this is adequate what is --6 THE WITNESS: Well, Princeton Hydro referred7 to a statement in the Corps of Engineers Manual for8 rock, for structures constructed on rock and it also9 included recommendations for slopes and these are for10 things like, for Corps of Engineers projects would be11 large dams, military work and things, or things that if12 they failed could produce catastrophic results. And so13 a factor of 2 would definitely be justified in that14 case. But for this slope, and I would say if Building D15 was going to be built on the slope, then the, but

produce catastrophic results. And so13 a factor of 2 would definitely be justified in that14 case. But for this slope, and I would say if Building D15 was going to be built on the slope, then the, but it's16 not, but if it was getting built on the slope then maybe17 that kind of a safety factor would be required. But the18 construction here is just, just to the, the west of the19 crest of the ridge and they have demonstrated that the20 influences of the structure wouldn't extend onto the21 slope. And the safety, they computed safety factors22 with the building in place and, and compared it to23 safety factors under existing conditions and there24 wasn't much of a change due to influence of the25

7 of 28 sheets Page 25 to 28 of 112 01/05/2026 03:19:18 PM 25 building.1 MAYOR McCARTNEY: And in your2 recommendations you said that soil erosion protection of3 the slope, how will you install that and what does that4 actually mean?5 THE WITNESS: Well, basically here you would6 ensure that the grading during construction didn't7 permit any flow, any runoff over the top of the slope.8 MAYOR McCARTNEY: You also mentioned that9 they should place slope indicators?10 THE WITNESS: Slope indicators, yes.11 MAYOR McCARTNEY: So if they do bend, as you12 referred to, what happens? What is the implication of13 that.14 THE WITNESS: Well, the implication is15 that -- well, we anticipate that, or at least it should16 be anticipated in the review of this project that17 blasting will be required to excavate 23 feet of rock on18 the one end of the building. And so that, and so this19 excavation work plan that we recommend be required they20 would have to do an evaluation on how much charge to do21 in each blast and that's usually dependent on the22 distance to the, to the structure to be protected. And23 ordinarily you would be looking at residences nearby, so24 the residences here are several hundred feet away from25 26 it. You wouldn't use several hundred feet in order to1 design the blasting charge. You would consider the2 slope to be the structure that's being protected and you3 would -- that distance ranges from about 40 to 100 feet.4 And so the design of the blasting program would have to,5 have to employ small charges and the excavation would6 proceed at a slower pace because of that. But the --7 there would be vibration monitoring and the slope8 indicators would indicate, they would indicate, they9 indicate movement. Relative movement. In other words,10 you have a long shaft with a tube in it, you lower a11 probe in and the slope, it can read back electronically12 the changes in slope going up and down and so over time13 you would, if you had a problem, let's say that the part14 of the tube that's fixed in the rock would not move but15 you would notice that the soil above the rock, you would16 see a big sweep in the curve and it would show its17 moving. It would be to everybody's benefit to employ18 these devices so that you would check during the19 excavation and you could demonstrate at the end of20 construction that we did that and hopefully it would21 indicate

everybody's benefit to employ18 these devices so that you would check during the19 excavation and you could demonstrate at the end of20 construction that we did that and hopefully it would21 indicate there was negligible movement and that would be22 the only way you could tell whether there was or there23 was not, otherwise there would be grounds for argument.24 And if you did notice it then you would have to modify25 27 the excavation plan if it was going on during the1 construction.2 MAYOR McCARTNEY: That's where I was going.3 Thank you. Seemed like quite a bit of conditions.4 CHAIRMAN BAGOFF: Mr. Klein.5 MR. KLEIN: The Mayor got most of my6 questions.7 You talked a little bit about, so we are8 talking about landslide hazard and the 1.7 factor and9 things like that. So you're pretty confident that --10 well, let me ask you it this way. The slope right now,11 naturally it could slide based on groundwater and all12 these other forces, that's just naturally the way it's13 sitting?14 THE WITNESS: I think that's to simplistic.15 MR. KLEIN: Oh, okay.16 THE WITNESS: It could slide, but I'm saying17 the analysis that were performed would, which did not18 include the most pessimistic ground water analysis,19 don't indicate, don't give an indication of, that there20 is a problem with stability, in our opinion. And, but21 then you're faced with this mapping that was done by the22 USGS and I think it concerns areas down the slope beyond23 the investigations that were performed. But we were24 unable to locate the basis for that particular25 28 classification and it's pretty unique to that area. In1 other words, the Watchung Ridge continues north and2 south and there were no areas mapped except at this3 location.4 MR. KLEIN: So the placement of that5 building, it's Building D with the jog in it?6 THE WITNESS: Right.7 MR. KLEIN: The location to the top of the8 slope and the slope itself, how do you feel about that9 location, distance from the top of the ridge, I'm not10 sure that ridge line, how far west it is of that?11 THE WITNESS: Well --12 MR. KLEIN: Is it to close?13 THE WITNESS: The analysis provided by14 Langan would indicate that it did not have a, as located15 it did not have a significant affect on the stability.16 In other words, the calculations with the building in17 place yielded the same safety factor as the calculations18 --19 MR. KLEIN: Before the

5 it did not have a significant affect on the stability.16 In other words, the calculations with the building in17 place yielded the same safety factor as the calculations18 --19 MR. KLEIN: Before the building is put20 there. Okay. Okay. That was my questions. Thank you.21 CHAIRMAN BAGOFF: Ms. Kapferer, do you have22 any questions for Mr. Kleinberg on his testimony?23 MS. KAPFERER: Thank you, Mr. Chairman.24 Thank you, Mr. Kleinberg.25