I agree with the suggestion on the silt responsibility. I think they can get grass growing on the slope soon and may have to re-seed in the spring. I am concerned about ongoing erosion from rain events with no grass. I would not ask them to make it a shallower slope, (would be considered additional work and they would expect pay). I would tell them that it was not shaped or quite as steep as it is now. If you do want them to shallow up the slope, 3:1 is considered mow-able. But since you want to enclose it ultimately, I would lean towards getting them to stabilize it with a grass of some sort. -----Original Message----- From: Jenkinson, Joel [mailto:Joel.Jenkinson@wgint.com] Sent: Friday, August 21, 2009 1:53 PM To: McIllwain, Frank O.; Clay Barnett Cc: Nancy Cline; Mark Acevedo; Siemens, Paul, T; Joe.Mcanally@wgint.com; david.foster@addisonairport.net Subject: RE: Millionaire Ditch - Garver Invoices Frank & Clay, After last night’s rain, a large volume of rock/sand/silt washed out of the box culvert and there was significant (but not severe) erosion of the north slope of the drainage channel. For Clay the good news may be that your big box culvert now appears to be clean and clear of silt and debris, although I would still be concerned about where that all came from. However, there was additional silt and sand coming from the RCP in the north wing wall, and that was still flowing after lunch today. I think this is probably coming from the construction site a little further north on Westgrove, on the east side of the street. You may want to visit with those folks about that. Immediately downstream of the concrete protection, there was significant scouring of the channel bottom, and further downstream there is a significant accumulation of small rocks, sand, and silt. With respect to the heavy silt and rock coming from the box culvert, I think that may be a one-time deal; it certainly won’t be anywhere near as bad going forward, because all that accumulated material has now been pushed down into the open channel. That being said, we need to get in there and clean out the silt, or the channel will quickly revert to the same mess we had before. The north side slope of the channel that Olden disturbed was not compacted, and now the top layer of soil has mostly washed away … there is a lot of rock showing. The airport has no objection to the wood fiber erosion control blankets. (Don’t those contain some grass seed as well?) However, if Olden has to come back and dress up that slope, it would be very nice (from our perspective) if they would shallow out the slope to where we could get a mower in and out of there safely, not unlike the drainage channel in the north RSA (where I believe the side slopes are 6:1). A shallower slope would also be more resistant to erosion, wouldn’t it? I can go back out there this afternoon and take some pictures, which I can then include in an e-mail to Kent Abella. I can also ask about the concrete flumes at that time. Is there anything else that needs to be included? Note that while they did clean out the open part of that big channel structure, they did not remove any of the silt that was up inside the box culvert (and it was not in their scope to do so). For that part of the channel, I am not convinced it would be fair to ask that they remove the additional silt. The downstream portion of the channel is a different story, however, because most of that material seems to have washed down into the channel from the north slope. Joel Joel Jenkinson Director, Addison Airport main: (972) 392-4850 fax: (972) 788-9334 _____ From: McIllwain, Frank O. [mailto:FOMcIllwain@GarverUSA.com] Sent: Friday, August 21, 2009 10:56 AM To: Clay Barnett Cc: Nancy Cline; Mark Acevedo; Jenkinson, Joel; Siemens, Paul, T Subject: RE: Millionaire Ditch - Garver Invoices Clay: The contractor disturbed much more of the north slope that we intended. The first attached picture shows the ditch prior to construction. The second picture shows the ditch at the beginning of the contractor’s construction. Ditch typical section A-A on the Sheet 2 of the attached plans shows that we designed flow line grading, not north bank reshaping. Our design didn’t need any re-vegetation or stabilization on the north slope. I think it’s reasonable to require the contractor to stabilize the north slope at his own cost, but I don’t think grass will grow this late in the year. How do you feel about wood fiber erosion control blankets? Frank McIllwain, PE Garver, LLC From: Clay Barnett [mailto:cbarnett@addisontx.gov] Sent: Friday, August 21, 2009 10:01 AM To: Siemens, Paul, T Cc: Nancy Cline; Mark Acevedo; McIllwain, Frank O.; Jenkinson, Joel Subject: RE: Millionaire Ditch - Garver Invoices Tim, Did they give you any unit prices? What do you recommend? Thanks, Clay Barnett, P.E. Town Engineer Town of Addison 16801 Westgrove Drive Addison, TX 75001-2818 Office: (972) 450-2857 P Please consider the environment before printing this email. -----Original Message----- From: Jenkinson, Joel [mailto:Joel.Jenkinson@wgint.com] Sent: Thursday, August 20, 2009 5:31 PM To: Clay Barnett Cc: PTSiemens@garverengineers.com; Nancy Cline; Mark Acevedo; McIllwain, Frank O. Subject: RE: Millionaire Ditch - Garver Invoices All: The bid was a lump sum price of $38,000 plus the $6,200 change order for silt removal and “reconstruction” of the third concrete flume. I agree that none of the concrete flumes were “reconstructed” and I also agree that the shotcrete is fine as-is, it will accomplish what it needs to with respect to preventing erosion of the slope. My question is with a lump sum like this, what kind of a price break are we looking for? With respect to stabilization of the north slope, their bid condition 11 states that restoration of turf or vegetation shall be by others … in other words, it looks to me as if stabilization of the north slope was not addressed, and Olden specifically said they will not restore vegetation. We are in late August, what can we put out there that will grow and hold the slope? Joel Joel Jenkinson Director, Addison Airport main: (972) 392-4850 fax: (972) 788-9334 _____ From: Clay Barnett [mailto:cbarnett@addisontx.gov] Sent: Thursday, August 20, 2009 4:50 PM To: Jenkinson, Joel Cc: PTSiemens@garverengineers.com; Nancy Cline; Mark Acevedo; McIllwain, Frank O. Subject: RE: Millionaire Ditch - Garver Invoices Joel, Nancy and I visited the ditch and have a couple of comments: 1. The three concrete flumes were not constructed as shown in the plans. I do not believe this is a problem, but I also do not believe they should be paid for them. It would be fair to remove the concrete pay items and increase the shotcrete pay item to compensate for the area. 2. They need to stabilize the northern bank. I am open to recommendations/solutions. If you have any questions, please let me know. Thanks, Clay Barnett, P.E. Town Engineer Town of Addison 16801 Westgrove Drive Addison, TX 75001-2818 Office: (972) 450-2857 P Please consider the environment before printing this email. -----Original Message----- From: Jenkinson, Joel [mailto:Joel.Jenkinson@wgint.com] Sent: Thursday, August 20, 2009 3:16 PM To: McIllwain, Frank O. Cc: EOSHINSK@dot.state.tx.us; HLORTON@dot.state.tx.us; PTSiemens@garverengineers.com; Nancy Cline; Clay Barnett; Mark Acevedo Subject: RE: Millionaire Ditch - Garver Invoices Frank, Thanks, we’ll start processing these invoices. I have attached some photos of the ditch during and after construction. That headwall by Westgrove Road is really something, I had no idea that all that concrete structure was there … amazing! So much of that structure was silted in so badly, with vegetation growing all over it, that I had no idea how much of the channel bottom was concrete. Olden did a really good job, they were in and out in less than a week. All projects should go this well. And you guys should have an interesting task ahead of you with the design work to put that drainage channel in a culvert when we get to that point. Hang on to that survey, it ought to come in handy. Regards, Joel Joel Jenkinson Director, Addison Airport main: (972) 392-4850 fax: (972) 788-9334 _____ From: McIllwain, Frank O. [mailto:FOMcIllwain@GarverUSA.com] Sent: Thursday, August 20, 2009 2:40 PM To: Jenkinson, Joel Cc: Siemens, Paul, T Subject: Millionaire Ditch - Garver Invoices Joel: The attached file contains two invoices for surveying and engineering for the ditch improvements. The first invoice is for Lamb-Star design surveys. The second invoice is for our work – Site investigation, plans, bidding, preconstruction meeting and one site visit during construction. Please let me know if you have any questions. 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