Agenda 06-04-2019 6-a - Major Subdivision Preliminary Plat Application

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93 east. There would be a left turn lane to get into the subdivision. As your headed west, there will be what we call a deceleration lane or a right-turn lane to get traffic off of the through lane and able to turn into the entrance. NC DOT 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 Pat mentioned,we did keep the entrance location far enough west so that none of the widening would impact this box culvert that crosses under Highway 70. We are staying far enough west that our widening will not impact any of that box culvert. Since last month,we've continued on and added the required landscaping to show on our landscape plan for you. As Pat mentioned,we have the required street trees that would be planted along each of the streets. This is per the ordinance requirements that you have to have a street tree spaced primarily every 100 feet with other small plantings between. This is a rendering of how we feel it would look once all is in place. The primary goal would be the preserve all the trees that are out there now along that buffer. To go over the stormwater managements for Orange County,this is Section 6.14 from the ordinance,we have to follow and meet the guidelines for Orange County which are all based on state regulations. We would need to protect the repairing areas, monitor the nitrogen and phosphorous load contributions that are proposed based on the development, and attenuate the flow which means we can't have any more flow leaving the site than prior to the development. Our devices need to manage that stormwater runoff and control the first inch of rainfall from all the project areas on the site. To treat the nitrogen and phosphorous we have to have a 85 percent TSS,total suspended solids, removal achieved through the devices that we install. These are the standards pretty much state wide. Orange County implements these same standards based on where they are in each river basin and each watershed. In that regard,we are proposing a multiple attack on stormwater. One would be disconnected impervious services on each lot which kind of covers the runoff from each roof, having treatment swells in areas where the runoff can't get to our primary stormwater devices, and level spreader filter strips used in connection with other stormwater devices including in buyer retention basins. Some folks were concerned about the stormwater and had discussed low impact development. We approach every project with a low impact development, approach. If we can meet stormwater requirements and treat stormwater 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 development, see how much trees are there, how much open areas there are, how much pasture,the types of land cover, and then you look at it again after proposed development with the houses,yard areas, in preserving tree areas and so forth. You check and see what the differences are in the different rates and these involve: infiltration of water into the ground; and then the runoff that occurs from the impervious that's added. We run it for this site, and it did not meet the percentage threshold for a true Lid design. In the rural design requirements, per this manual that was started back in 2009,they referred to the Best Management Practices to use devices like infiltration devices, level spreaders, sand filters, pocket wetland, and permeable pavers to manage stormwater in a low impact manner. Hunter Spitzer:You said for the Lid on the water treatment that you did not meet the percent required. Tim Smith: The LID manual is not a regulated booklet. It's a guideline for how you would do a LID analysis. It was just a little over the threshold of what it needed to be. If it met the requirements,we wouldn't have to do anything. Because of the type of development it is,we are above that threshold and so we have to implement stormwater control per the UDO. Patrick Mallett: Low impact design in terms of Orange County and stormwater and erosion control is a classification. By virtue of the amount of land disturbance just for the roads, it brings it out of that category in terms of the stormwater classification. In Orange County,whether you are a low impact designer or not, determines the cost per acre for your stormwater permits and how you are classified. There is also a difference between low-impact design as it's classified, required, or evaluated which causes the requirements for your stormwater and erosion control. You can still do low impact principals. Two points I would like to clarify. When I discussed the building setbacks around the perimeter,that's the perimeter setback which is 100-feet around the perimeter of the project. You also have an offered 120-foot building setback along US 70. You have single family lots;those also have building setbacks. They're proposing you have 30-foot front set back, and 15-foot side and rear setbacks. There are four lots along US 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 requirements so in essence they would tread lightly and use that as a last resort, because if you take out a tree or don't meet the landscape requirements, and you put in a well or a septic system that you can't put landscaping in, you have to find some other place to put it. That can eventually become mathematically impossible. Tim Smith: We are looking to approach to our stormwater management where we'll have multiple treatments from several different types of devices which are all in the realm of low impact devices with how we treat the water. I just