Planning Board agenda 060519 - Laserfiche WebLink

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D R A F T has approved this layout as we continue on we’ll be adding the grading for that and all the details that go with it. As 275 Pat mentioned, we did keep the entrance location far enough west so that none of the widening would impact this 276 box culvert that crosses under Highway 70. We are staying far enough west that our widening will not impact any of 277 that box culvert. Since last month, we’ve continued on and added the required landscaping to show on our 278 landscape plan for you. As Pat mentioned, we have the required street trees that would be planted along each of the 279 streets. This is per the ordinance requirements that you have to have a street tree spaced primarily every 100 feet 280 with other small plantings between. This is a rendering of how we feel it would look once all is in place. The primary 281 goal would be the preserve all the trees that are out there now along that buffer. To go over the stormwater 282 managements for Orange County, this is Section 6.14 from the ordinance, we have to follow and meet the guidelines 283 for Orange County which are all based on state regulations. We would need to protect the repairing areas, monitor 284 the nitrogen and phosphorous load contributions that are proposed based on the development, and attenuate the 285 flow which means we can’t have any more flow leaving the site than prior to the development. Our devices need to 286 manage that stormwater runoff and control the first inch of rainfall from all the project areas on the site. To treat the 287 nitrogen and phosphorous we have to have a 85 percent TSS, total suspended solids, removal achieved through the 288 devices that we install. These are the standards pretty much state wide. Orange County implements these same 289 standards based on where they are in each river basin and each watershed. In that regard, we are proposing a 290 multiple attack on stormwater. One would be disconnected impervious services on each lot which kind of covers the 291 runoff from each roof, having treatment swells in areas where the runoff can’t get to our primary stormwater devices,292 and level spreader filter strips used in connection with other stormwater devices including in buyer retention basins. 293 Some folks were concerned about the stormwater and had discussed low impact development. We approach every 294 project with a low impact development, approach. If we can meet stormwater requirements and treat stormwater 295 based on a low impact design, this is our primary goal. In a true sense of a Lid analysis, you check your site prior to 296 development, see how much trees are there, how much open areas there are, how much pasture, the types of land 297 cover, and then you look at it again after proposed development with the houses, yard areas, in preserving tree areas 298 and so forth. You check and see what the differences are in the different rates and these involve: infiltration of water 299 into the ground; and then the runoff that occurs from the impervious that’s added. We run it for this site, and it did 300 not meet the percentage threshold for a true Lid design. In the rural design requirements, per this manual that was 301 started back in 2009, they referred to the Best Management Practices to use devices like infiltration devices, level 302 spreaders, sand filters, pocket wetland, and permeable pavers to manage stormwater in a low impact manner. 303 304 Hunter Spitzer: You said for the Lid on the water treatment that you did not meet the percent required.305 306 Tim Smith: The LID manual is not a regulated booklet. It’s a guideline for how you would do a LID analysis. It was 307 just a little over the threshold of what it needed to be. If it met the requirements, we wouldn’t have to do anything. 308 Because of the type of development it is, we are above that threshold and so we have to implement stormwater 309 control per the UDO. 310 311 Patrick Mallett: Low impact design in terms of Orange County and stormwater and erosion control is a classification.312 By virtue of the amount of land disturbance just for the roads, it brings it out of that category in terms of the 313 stormwater classification. In Orange County, whether you are a low impact designer or not, determines the cost per 314 acre for your stormwater permits and how you are classified. There is also a difference between low-impact design 315 as it’s classified, required, or evaluated which causes the requirements for your stormwater and erosion control. You316 can still do low impact principals. Two points I would like to clarify. When I discussed the building setbacks around 317 the perimeter, that’s the perimeter setback which is 100-feet around the perimeter of the project. You also have an 318 offered 120-foot building setback along US 70. You have single family lots; those also have building setbacks. 319 They’re proposing you have 30-foot front set back, and 15-foot side and rear setbacks. There are four lots along US 320 70 that technically could have a well as close to 50 feet to the right of way, but you still have to meet the landscape 321 requirements so in essence they would tread lightly and use that as a last resort, because if you take out a tree or 322 don’t meet the landscape requirements, and you put in a well or a septic system that you can’t put landscaping in, 323 you have to find some other place to put it. That can eventually become mathematically impossible. 324 325 Tim Smith: We are looking to approach to our stormwater management where we’ll have multiple treatments from 326 several different types of devices which are all in the realm of low impact devices with how we treat the water. I just 327 wanted to go over this to give you a further perspective on how we propose to finish our design with regards to 328 stormwater. 329 10