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Home My WebLink AboutCorrespondence March 2020 Grant, Kelly From:Grant, Kelly Sent:Monday, March 23, 2020 1:52 PM To:'Daniel A. Ojala PE, PLS' Subject:RE: 66 Nottingham Drive DCE file #18-325 Thanks Dan, Yes I suggest revising the plan to focus on the area east of the bank line. -----Original Message----- From: Daniel A. Ojala PE, PLS \[mailto:downcape@downcape.com\] Sent: Monday, March 23, 2020 9:47 AM To: Grant, Kelly <KGrant@yarmouth.ma.us> Subject: RE: 66 Nottingham Drive DCE file #18-325 Attention! This email originates outside of the organization. Do not open attachments or click links unless you are sure this email is from a known sender and you know the content is safe. Call the sender to verify if unsure. Otherwise delete this email. ________________________________ I was looking at the exact grade at the flood zone line, but I concur there is enough 10% in that area to move the end of the bank over, here is a final draft, look ok? (put bank at AE14 flood zone line, as this is most conservative). Can we avoid variances when working to East of the line, and just respect a buffer that is upgradient of the bank? (i.e work in deck area ok). Thanks, Daniel A. Ojala PE, PLS down cape engineering, inc. 939 Main St. Yarmouthport, MA 1-508-362-4541 x106 1-508-362-9880 fax downcape@downcape.com This Electronic Message contains information from the engineering firm of down cape engineering, inc., which may be privileged. The information is intended to be for the use of the addressee only. If you are not the addressee, note that any disclosure, copy, distribution or use of the contents of this message is prohibited. -----Original Message----- From: Grant, Kelly \[mailto:KGrant@yarmouth.ma.us\] Sent: Wednesday, March 18, 2020 12:00 PM To: 'Daniel A. Ojala PE, PLS' <downcape@downcape.com> Subject: RE: 66 Nottingham Drive DCE file #18-325 Hi Dan 1 So disregarding the old delineation, and using 92-1, the slope around the current flood zone has a slope steeper than 10:1 per attached image (bold line sections). In this case the flood zone line would be the top of bank ending where the slope is less than 10:1. I am calculating the bank to extend further than you are showing on the plan. Thanks Kelly -----Original Message----- From: Daniel A. Ojala PE, PLS \[mailto:downcape@downcape.com\] Sent: Monday, March 16, 2020 7:19 PM To: Grant, Kelly <KGrant@yarmouth.ma.us> Subject: RE: 66 Nottingham Drive DCE file #18-325 Attention! This email originates outside of the organization. Do not open attachments or click links unless you are sure this email is from a known sender and you know the content is safe. Call the sender to verify if unsure. Otherwise delete this email. ________________________________ Hi, Kelly: I think with sea level rise and the new mapping, the old bank delineation is not relevant, that was at elevation 11 NGVD29 which is elevation 10 NAVD88, and that area is pretty flat. We generally focus on the 100 year flood zone and look at the slope there, slight variations is slope or small ridges well below this level are only considered Land Subject to Coastal Storm Flowage unless clearly steep and/or eroding so a likely sediment source. There is no specific guidance on this, it is just how it has been interpreted for many years. (the town of Barnstable simply acknowledges state banks but then ignores their setbacks or performance standards for anything under 18% which is a "Town Bank", for instance). I think we can safely regulate these diminimous lower slope areas as Land Subject to Coastal Storm Flowage, rather than try to tease out little discontinuous banks well below the 100 year flood elevation which is four feet higher than previous FEMA mapping. These areas would simply be inundated under such a storm and would serve no purpose during the largest events. Especially in an instance like here where the area is vegetated and stable, and the bank flattens out and becomes LSCSF in many places, and LSCSF does not have any specific performance standards. There is no way these tiny slopes well below the base flood elevation would show up on a USGS quad map like the original guidance documents for coastal banks mention. Because of the generally gentle slope and heavy vegetation, and seaward stable salt marsh, they are not sediment sources, are not susceptible to erosion, and contain flood waters in an identical manner to the LSCSF at just under ten percent grade does. 2 Since there is a salt marsh with a buffer imposed by the Conservation Commission which protects a similar area as would be protected if a lower tiered bank was delineated, it should be found in this case that these low areas adjacent the salt marsh are diminimous, discontinuous, and not significant enough vertical buffers or sediment sources to be mapped as coastal banks. There is a manmade borrow pit West of locus which meets the definition of a Coastal Bank, then the slope is natural and much less than 25%, so is technically a coastal bank at the flood zone line until it peters out onsite and becomes <10%, where no bank would exist, save teasing out small slopes slightly greater than 10% near the salt marsh. (figure 7 on 92-1 Policy). You will see on the old Demarest McLennan plan the "bank" was at the old 100 year flood elevation of 11, which is 10 NAVD88, and the slopes bounce up and down less and greater than ten percent, so was always a discontinuous marginal bank at best even prior to the flood zone change. Please let me know your thoughts. Daniel A. Ojala PE, PLS down cape engineering, inc. 939 Main St. Yarmouthport, MA 1-508-362-4541 x106 1-508-362-9880 fax downcape@downcape.com This Electronic Message contains information from the engineering firm of down cape engineering, inc., which may be privileged. The information is intended to be for the use of the addressee only. If you are not the addressee, note that any disclosure, copy, distribution or use of the contents of this message is prohibited. -----Original Message----- From: Grant, Kelly \[mailto:KGrant@yarmouth.ma.us\] Sent: Monday, March 16, 2020 4:06 PM To: Daniel A. Ojala PE, PLS <downcape@downcape.com> Subject: Re: 66 Nottingham Drive DCE file #18-325 Hi Dan I am struggling to reconcile this with my transects on the original plan. There are also a couple of coastal banks shown on the old plan that end at the old flood zone line. With the new flood zone line this would move the bank further up. \[image1.jpeg\] Sent from my iPhone On Mar 13, 2020, at 7:15 PM, Daniel A. Ojala PE, PLS <downcape@downcape.com<mailto:downcape@downcape.com>> wrote: Attention! This email originates outside of the organization. Do not open attachments or click links unless you are sure this email is from a known sender and you know the content is safe. Call the sender to verify if unsure. Otherwise delete this email. ________________________________ 3 <image002.gif> Kelly: Per your request we measured additional points at the site, and at the old borrow pit West of the property. I show a 50' setback off the bank, up perpendicular to the bank, as that is what would theoretically erode during a storm. Where there is no bank, I don't feel there should be a buffer, so I only show only buffer upgradient of a bank, would you concur with this analysis? Thanks, Daniel A. Ojala PE, PLS down cape engineering, inc.<http://downcape.com/> 939 Main St. Yarmouthport, MA 1-508-362-4541 x106 1-508-362-9880 fax downcape@downcape.com<mailto:downcape@downcape.com> This Electronic Message contains information from the engineering firm of down cape engineering, inc., which may be privileged. The information is intended to be for the use of the addressee only. If you are not the addressee, note that any disclosure, copy, distribution or use of the contents of this message is prohibited. From: Daniel A. Ojala PE, PLS \[mailto:downcape@downcape.com\] Sent: Tuesday, December 03, 2019 2:20 PM To: 'Grant, Kelly' <KGrant@yarmouth.ma.us<mailto:KGrant@yarmouth.ma.us>> Cc: 'phil@cheneylandscapedesign.com<mailto:phil@cheneylandscapedesign.com>' <phil@cheneylandscapedesign.com<mailto:phil@cheneylandscapedesign.com>> Subject: 66 Nottingham Drive DCE file #18-325 Hi, Kelly: Phil Cheney called and said the older plans had a coastal bank delineated, but the newer approved plan did not. The flood zone has changed and the slope at the 100 year flood elevation is less than 10 percent, so per the DEP Policy, there is currently no coastal bank on this property. A sketch which plots at 1"=20' on letter size paper is attached with transects showing the less than ten percent. Please call or email with any questions. Thanks, Daniel A. Ojala PE, PLS down cape engineering, inc.<http://downcape.com/> 939 Main St. Yarmouthport, MA 1-508-362-4541 x106 4 1-508-362-9880 fax downcape@downcape.com<mailto:downcape@downcape.com> This Electronic Message contains information from the engineering firm of down cape engineering, inc., which may be privileged. The information is intended to be for the use of the addressee only. If you are not the addressee, note that any disclosure, copy, distribution or use of the contents of this message is prohibited. <18-325 SABEN 24x36 Site (1).pdf> 5