January 14, 2026, Planning Board Special Meeting - WEHI Transcript

02/03/2026 04:49:05 PM Page 13 to 16 of 122 4 of 53 sheets 13 He is referring mostly to the root cohesion.1 Q. And what he's saying, if I interpret it correctly2 is, well, to get, you know, absolute stability here with3 topsoil you need an angle of friction of at least 454 degrees and he says, "Which is not realistic in the5 upper few feet." What he really means is that you don't6 achieve that in nature with those types of particles.7 Is that fair to say?8 Right.9 A. Can I clarify something or add something?10 Yeah.11 Q. In his discussion we are talking about a12 A. particular case where the groundwater level has risen to13 the surface and that it's flowing downhill parallel to14 the surface and it's supplying additional -- it's15 providing a buoyant uplift, which reduces the frictional16 resistance. And this is a case that wasn't evaluated17 either by the opposer engineer or the applicants18 engineer and it's a case that we recommended that they19 address.20 Now, I fully understand that, you alluded to that21 Q. at the last meeting. So I appreciate that.22 Okay. I wasn't sure that you did.23 A. I do understand that. Thank you.24 Q. Now, in terms of root cohesion he's saying well,25 14 since we don't have 45 degrees angle of friction, in our1 view the slopes stable, so something else is accounting2 for the stability. And he infers that must be root3 cohesion, is that fair?4 Right. But, and if I can just describe a little5 A. furthermore. He's describing what would have to happen6 if a condition of flow parallel to the slope had7 occurred, but we don't know that that has ever occurred.8 Well, I understand entirely. And, again, you9 Q. alluded to that previously.10 He says that in their view the slope is stable11 and therefore since it can't be stable only because of12 the angle of friction, which you can't reach here,13 something else accounts for that and that's root14 cohesion?15 It could be stable if that condition didn't16 A. exist.17 We are dealing with the potential for that18 Q. condition?19 But if it ever did occur then it would rely on20 A. root cohesion.21 Yes.22 Q. And since he is inferring that since there's no23 A. evidence on the slope that it ever occurred in either24 right the root cohesion -- if the groundwater condition25 15 had occurred the root cohesion resisted it.1 Right. He's saying that assuming it's stable,2 Q. and this hasn't

it ever occurred in either24 right the root cohesion -- if the groundwater condition25 15 had occurred the root cohesion resisted it.1 Right. He's saying that assuming it's stable,2 Q. and this hasn't happened, it's most likely because3 there's enough root cohesion to make up for the reduced4 angle of friction, is that fair to say?5 It seems fair to say.6 A. Thank you.7 Q. Now, he then says that -- he goes into the8 analysis, I don't need to address it in detail as to why9 he feels, it's a short analysis, two or three lines, why10 he feels root cohesion is adequate and he refers to11 various researchers who have found root cohesion values12 ranging from 200 pounds per foot for clear cuts and13 natural wooded forested lands 500 pounds per square14 foot. He says, "The site is predominately wooded.15 However, if C equals 100 pounds per square foot root16 cohesion is used, FS values would be well over 1.5, i.e.17 1.7 is acceptable." And the slope, "for the slopes in18 question." So he's saying that, assuming we use a 10019 PSF root cohesion, the FS value would be above 1.5 and20 therefore he endorses his 1.5 usage. That's roughly21 what he is saying, right?22 Yes.23 A. Okay.24 Q. Now, at the end of all that, you then say, CMEs25 16 response, "We recommend that Langan provide a formal1 response to the Planning Board on the basis described2 herein to address this issue." Now, what do you mean3 by, formal response?4 It would be in a letter, a technical letter5 A. signed and sealed by the engineer indicating what his6 analysis of the condition was rather than just an7 e-mail.8 In other words, something that's submitted under9 Q. signature of an engineer or potentially under oath?10 Correct.11 A. He could testify and introduce his report, but12 Q. not just an e-mail that's unaccountable essentially?13 That's what I meant.14 A. Good.15 Q. Now, did you see that submitted as of today?16 No.17 A. Okay.18 Q. Now, looking at Paragraph 3, are you in a19 position -- strike that.20 You haven't issued any opinion on his use of the21 100 pounds per square foot root cohesion figure, have22 you?23 I will have to testify that I am not an expert on24 A. developing the value for root cohesion. I would have to25