F-2 C15-2022-0012 PRESENTATION — original pdf

Backup

Monday, June 6, 2022 To: Board of Adjustments City of Austin 301 W 2nd St, Austin, TX 78701 Reference: - Supplemental Letter - 2717 Long Bow Trail - Case # C15-2022-0012 I am writing to provide you with the additional information requested by the Board of Adjustments during our meeting on April 11, 2022. I have attached a copy of the supporting documents for the comments below and answer the questions and concerns you had during the hearing. Directly below, you will see our justifications for approval, and below that is the backup information concerning the property and the reasoning for our justifications. Justifications for approval: - The less is more version 1. Based on the slope analysis, the current site only allows for 580.35 sf of IC. We request 1,900 sf of impervious coverage to meet the Apache Shores POA minimum living area requirements, a two-car garage for proper parking, and the required driveway using ribbon designs. a. As an item of reference, this lot will only have 19.5% of the total site area, which is half of the standard IC allowed under typical zoning regulations. 2. The new design that the developer created reduced the originally requested IC by 43% by utilizing a single-car ribbon drive and reducing the house size and footprint. 3. Based on the engineering report and design provided by 3PX engineers, they created a drainage plan that will prevent any additional/adverse runoff created by the proposed development. This plan was created by using Vegetative Strips that are allowed under the ECM Section 1 - 1.6.7 (B) 4. Without this variance, we will not be able to develop any structure on this property that will meet the COA development regulations and the Apache Shores POA development requirements on the deed restrictions. Backup Information Zoning Regulations: The primary basis of our request is that the property has been zoned for both LA (Lake Austin) zoning and the Lake Austin overlay. As shown below, both regulations require a min. of 1-acre lot size per the City of Austin development regulations. The application of the LA regulations on this lot makes it non-developable for reasonable use. The LA regulations are also shown as the strictest zoning regulations specified in 25-2-33 (b). 1. Per 25-2-492 site development regulations, the LA zoned lot must be a minimum of 43,560 SF in size (1 acre), and the lot in question is only 8,822.11 sf (.20 acres). In addition, all LA zone lots are governed by 25-2-551 (C)-3 Impervious coverage restrictions based on a slope analysis of the property. 2. Per 25-2-53 of the Land Development Code - Lake Austin residence (LA) district is the designation for a low density single-family residential use on a lot that is a minimum of one acre, and that is located 1,000 feet or less, measured horizontally, from the 492.8-foot topographic contour line on either side of Lake Austin. 3. The City of Austin zoning guide published in September of 2016 in chapter II states the following. a. The City of Austin has established twelve Zoning Principles to preserve the compatibility of land uses. City Staff, stakeholders, and property owners should use the following principles to evaluate all zoning requests. i. Zoning should be consistent with the Future Land Use Map (FLUM) or adopted neighborhood plan. ii. Zoning should satisfy a public need and not constitute a grant of special privilege to an individual owner; the 1. This item does not apply to our case request should not result in spot zoning. 1. Within Apache Shores POA, less than 5% of the overall community has any form of zoning regulation. The current overlay unreasonably restricts the lot’s development capabilities. iii. Granting a zoning request should result in equal treatment of similarly situated properties. 1. Within Apache Shores POA, less than 5% of the overall community has any form of zoning regulation. The current overlay unreasonably restricts the lot’s development capabilities. Lots as close as 100’ away have no zoning regulations 2. iv. Granting the zoning should not in any way set an undesirable precedent for other properties in the neighborhood or within other areas of the city. 1. This is a lot-specific request on a non-conforming lot and would not result in any negative precedent. v. Zoning should allow for reasonable use of the property. 1. The current zoning does not allow for any reasonable use of the property. vi. Zoning changes should promote compatibility with adjacent and nearby uses and should not negatively impact the neighborhood character. 1. The request that we are asking for does not put the development capabilities of this property above or beyond the adjacent properties. vii. Zoning should promote a transition between adjacent and nearby zoning districts, land uses, and development intensities. 1. The request does not change the land use or density of the area. viii. Zoning should promote the policy of locating retail and more intensive zoning near the intersections of arterial roadways or at the intersections of arterials and major collectors. 1. This section does not apply to our request. ix. The request should serve to protect and preserve places and areas of historical and cultural significance. • Zoning should promote clearly identified community goals such as creating employment opportunities or providing affordable housing. 1. The request for Impervious Coverage is being made to develop single-family homes that are desperately needed in the greater Austin area. x. A change in conditions has occurred within the area, indicating that there is a basis for changing the originally established zoning and/or development restrictions for the property. 1. Before 2014 this property did not have any zoning regulations. This zoning overlay was added to the property making the lots non-developable. xi. The rezoning should be consistent with the policies adopted by the City Council or Planning Commission/Zoning and Platting Commission. 1. The City of Austin has been diligent in allowing for additional development of living units as it is necessary for future growth and the people who are currently here. Apache Shores HOA Regulations: The following regulations are required by the deed restrictions within the community. These regulations were adopted on November 19, 1969, and recorded with Travis County document # 23- 2467 1. Paragraph #3 states that no residence shall have less than 650 SF of living space on the ground or first floor exclusive of the porch area. Neighboring Properties: It has come into question the size of the proposed homes compared to the adjacent houses. We have gone through the Travis County property records and have identified the following. 1. Based on the map attached to this report, 9 houses within a 1,000-foot radius of this lot are within the size range of the proposed projects. If you take the average size of all the houses shown on the map, you will get an average size of 2,443 SF. a. A map showing the locations of the houses along with the TCAD information is attached to this packet. 2. On this map, you will also see 11 vacant lots on the same road (Long Bow Trail) that will be developed, and these lots are not within the COA LA zoning regulations, so they will most likely be constructed the same size larger than our proposed structure. Conclusion: As you can see, based on the information provided in this report and the prior documentation, there are many reasons why this variance should be approved. I understand that the biggest concern of this area has to do with the Lake Austin watershed, and we have provided an engineered plan that will eliminate that concern. Regards, Jonathan Kaplan Managing Member Urban Building Services of Texas LLC 512-768-2789 ext. 501 Legend Streets Jurisdiction FULL PURPOSE LIMITED PURPOSE OTHER CITY LIMITS OTHER CITIES ETJ TCAD Parcels Lot Line EXTRATERRITORIAL JURISDICTION 2 MILE ETJ AGRICULTURAL AGREEMENT 0.2 0 0.08 0.2 Miles NAD_1983_StatePlane_Texas_Central_FIPS_4203_Feet Date Printed: This product is for informational purposes and may not have been prepared for or be suitable for legal, engineering, or surveying purposes. It does not represent an on-the-ground survey. This product has been produced by the City of Austin for the sole purpose of geographic reference. No warranty is made by the City of Austin regarding specific accuracy or completeness. 1: 4,800 Notes 1 " 0 ' - 4 1 / 2 1 / 2 C R Z 10' - 6" 1/2 CRZ E " 0 0 ' 0 0 ° 0 N ' . 8 9 9 4 1 " 0 - 5' 5' - 0" 5' - 0" E " 0 0 ' 0 0 ° 0 N ' . 8 9 9 4 1 T2 1 " 0 ' - 4 1 / 2 1 / 2 C R Z 38' - 0" 11' - 0" 10' - 6" 1/2 CRZ 2717 Long Bow 1900 SF IC 23' - 0" 15' - 0" 11' - 0" " 0 - ' 0 4 " 6 - ' 9 T6 10' - 9 31/32" 1 2717 - Slope 1" = 10'-0" 2 2717 - Survey 1" = 10'-0" " 0 - ' 0 1 2717 - Slope Analysis - Net Site Area Material: Range Material: Area IC Breakdown Option 1 IC Breakdown Option 2 0.00% to 15.00% 748 SF x 35% = 261.8 x 40% = 299.2 x 40% = 299.2 6/6/2022 1:22:30 PM 15.00% to 25.00% 25.00% to 35.00% 2,333 SF 1,705 SF x 10% = 233.3 x 05% = 85.25 x 40% = 933.2 x 40% = 933.2 x 40% = 682 x 15% = 255.75 35.00% to 4,459.59% 5,255 SF 0 x 0% = 0 x 8% = 420.4 Allowed IC = 580.35 SF Proposed IC = 1,914 SF Proposed IC = 1908.55 SF SHEET NUMBER: Certification # 44-752 Office: 512-596-HOME (4663) Mobile: 512-920-3439 Email: jon@urbandesignsllc.com WWW.URBANDESIGNSLLC.COM The drawings, specifications, ideas , designs, and arrangements presented herein are and shall remain the property of Urban Designs. No part thereof shall be copied, disclosed to others or used in connection with any work or project other than the specific project for which they were prepared and developed without the written consent of Urban Designs. Visual contact with these drawings shall constitute conclusive evidence of acceptance of these restrictions. n i t s u A , l i a r T w o B g n o L 7 1 7 2 + 5 1 7 2 l t n e m p o e v e D e g a l l i V t r A CONSTRUCTION DOCUMENTS l s i s y a n A e t i S N O I T A M R O F N I T C E J O R P DRAWING TITLE: Site Plan - LA 22" X 34" SCALE: 1" = 10'-0" 11" X 17" SCALE: HALF SCALE ISSUES DATE: DRAWN BY: Author 2717 Stormwater Drainage report For Single Family Residence 271 Longbow Trail, Austin TX Prepared By: Tony Puljic, P.E. 3PX Engineering May 27th, 2022 3PXEngineering New Residence, 271 Longbow Trail Release rate and detention calculation for the 10-Yr. Storm Event Using the 2-Year release rate 5/28/2022 Calculate Composite "c" of Existing Area TOTAL IMPERVIOUS GRAVEL PERVIOUS AREA = AREA = AREA = AREA = 0.2067 ACRE 0.0000 ACRE 0.0000 ACRE 0.2067 ACRE COMPOSITE "c" = 0.45 Existing Release Rate from 2-Year Storm Event (See Exhibit of Existing Drainage Area for 'S' &'Tc') Q =C * I * A "c" Value = 0.9 "c" Value = 0.85 "c" Value = 0.45 C = I = A = Q = 0.45 (From above calculation) 6.30 inches/hour, (B 0.21 acres 0.5860 cfs (Max. release rate for proposed condition) Calculate Composite "c" of proposed development TOTAL IMPERVIOUS GRAVEL PERVIOUS AREA = AREA = AREA = AREA = 0.2067 ACRE 0.0460 ACRE 0.0000 ACRE 0.1607 ACRE COMPOSITE "c" = 0.55 "c" Value = 0.9 "c" Value = 0.85 "c" Value = 0.45 INTRODUCTION: The subject parcel is approximately 0. the property. A new house and driveway are being proposed to be built on the site. As a result of the new improvements, thee new impervious area added to the site will be 2003.76 s.f., s.f. and is wooded. There is no existing impervious area on Based on FEMA maps the site is located within Zone X of the flood plain. See attached Firmette in appendix. FEMA FLOOD PLAIN INFO: TOPOGRAPHY: HYDROLOGIC PATTERNS: STORMWATER: METHODOLOGY: The site is on a hill with a slope of approximately 3 % from the back of the property to the front of the property. The site is being proposed within an existing residential subdivision. There are no features that will affect the drainage patterns of streams, wetlands, seeps, springs, closed depressions, or drainage swales and ditches. The natural flow of water flows from the back of the property to the front of the property north to south. The proposed grading plan does not alter the drainage pattern nor does it direct water into the neighbor’s yards. The site is designed such that water flows into an underground basin. Based on the size of the development, the proposed residence, and the site will be required to discharge stormwater such that the post-development peak runoff is below the discharge rates for the 2,10, 25, and 100-year design storms. Calculations were made using the rational method. The time of concentration was determined by equation 2-5 in the City Code and determined to be .63 min. Based on the result, the minimum time of concentration of 5 min. was used. The amount of detention required was determined by determining the existing 2-year release rate and determining the post-development runoff for the 2,10 25, and 100-year storm events. Detention will be provided in a storage tank in front of the property. Also, a vegetative strip was designed based on Austin standards as a BMP prior to stormwater discharging from the property. Sincerely, 3PX Engineering 3PXEngineering New Residence, 271 Longbow Trail Release rate and detention calculation for the 10-Yr. Storm Event Using the 2-Year release rate 5/28/2022 Calculate Composite "c" of Existing Area TOTAL IMPERVIOUS GRAVEL PERVIOUS AREA = AREA = AREA = AREA = 0.2067 ACRE 0.0000 ACRE 0.0000 ACRE 0.2067 ACRE COMPOSITE "c" = 0.45 Existing Release Rate from 2-Year Storm Event (See Exhibit of Existing Drainage Area for 'S' &'Tc') Q =C * I * A "c" Value = 0.9 "c" Value = 0.85 "c" Value = 0.45 C = I = A = Q = 0.45 (From above calculation) 6.30 inches/hour, (B 0.21 acres 0.5860 cfs (Max. release rate for proposed condition) Calculate Composite "c" of proposed development TOTAL IMPERVIOUS GRAVEL PERVIOUS AREA = AREA = AREA = AREA = 0.2067 ACRE 0.0460 ACRE 0.0000 ACRE 0.1607 ACRE COMPOSITE "c" = 0.55 "c" Value = 0.9 "c" Value = 0.85 "c" Value = 0.45 DETENTION REQUIRED (BASED City of Austin Data) DURATION (HOURS) I (IN/HR) INFLOW STORED (CFS) (CFS) RESERVOIR (AC-FT) 8.5700 0.975 0.389 0.0027 MAX 0.0833 0.2500 0.5000 1.0000 2.0000 3.0000 6.0000 5.8800 0.669 0.083 3.9600 0.4503 -0.1357 2.6800 0.305 -0.281 1.7100 0.194 -0.392 1.2400 0.141 -0.445 0.7020 0.080 -0.506 12.0000 0.4010 0.046 -0.540 24.0000 0.2540 0.029 -0.557 0.0017 -0.0057 -0.0234 -0.0653 -0.1112 -0.2531 -0.5404 -1.1142 ATTACHMENTS 3PXEngineering DETENTION REQUIRED (BASED City of Austin Data) DURATION (HOURS) I (IN/HR) INFLOW STORED (CFS) (CFS) RESERVOIR (AC-FT) 0.0833 0.2500 0.5000 1.0000 2.0000 3.0000 6.0000 5.7600 0.655 0.069 0.0005 MAX 3.9200 0.446 -0.140 -0.0029 2.6400 0.3002 -0.2858 -0.0119 1.7200 0.196 -0.390 1.0800 0.123 -0.463 0.7773 0.088 -0.498 0.4450 0.051 -0.535 12.0000 0.2550 0.029 -0.557 24.0000 0.1430 0.016 -0.570 -0.0325 -0.0772 -0.1244 -0.2677 -0.5570 -1.1395 New Residence, 271 Longbow Trail Release rate and detention calculation for the 25-Yr. Storm Event Using the 2-Year release rate 5/28/2022 Calculate Composite "c" of Existing Area TOTAL IMPERVIOUS GRAVEL PERVIOUS AREA = AREA = AREA = AREA = 0.2067 ACRE 0.0000 ACRE 0.0000 ACRE 0.2067 ACRE COMPOSITE "c" = 0.45 Existing Release Rate from 2-Year Storm Event (See Exhibit of Existing Drainage Area for 'S' &'Tc') Q =C * I * A "c" Value = 0.9 "c" Value = 0.85 "c" Value = 0.45 C = I = A = Q = 0.45 (From above calculation) 6.30 inches/hour, (B 0.21 acres 0.5860 cfs (Max. release rate for proposed condition) Calculate Composite "c" of proposed development TOTAL IMPERVIOUS GRAVEL PERVIOUS AREA = AREA = AREA = AREA = 0.2067 ACRE 0.0460 ACRE 0.0000 ACRE 0.1607 ACRE COMPOSITE "c" = 0.55 "c" Value = 0.9 "c" Value = 0.85 "c" Value = 0.45 DETENTION REQUIRED (BASED City of Austin Data) DURATION (HOURS) I (IN/HR) INFLOW STORED (CFS) (CFS) RESERVOIR (AC-FT) 0.0833 0.2500 0.5000 1.0000 2.0000 3.0000 6.0000 10.1000 1.149 0.563 0.0039 7.0400 0.801 0.215 0.0045 MAX 4.7200 0.5367 -0.0493 -0.0021 3.2800 0.373 -0.213 2.1000 0.239 -0.347 1.5200 0.173 -0.413 0.8570 0.097 -0.489 12.0000 0.4920 0.056 -0.530 24.0000 0.3180 0.036 -0.550 -0.0178 -0.0579 -0.1033 -0.2443 -0.5300 -1.0997 New Residence, 271 Longbow Trail Release rate and detention calculation for the 100-Yr. Storm Event Using the 2-Year release rate 5/28/2022 Calculate Composite "c" of Existing Area TOTAL IMPERVIOUS GRAVEL PERVIOUS AREA = AREA = AREA = AREA = 0.2067 ACRE 0.0000 ACRE 0.0000 ACRE 0.2067 ACRE COMPOSITE "c" = 0.45 Existing Release Rate from 2-Year Storm Event (See Exhibit of Existing Drainage Area for 'S' &'Tc') Q =C * I * A "c" Value = 0.9 "c" Value = 0.85 "c" Value = 0.45 C = I = A = Q = 0.45 (From above calculation) 6.30 inches/hour, (B 0.21 acres 0.5860 cfs (Max. release rate for proposed condition) Calculate Composite "c" of proposed development TOTAL IMPERVIOUS GRAVEL PERVIOUS AREA = AREA = AREA = AREA = 0.2067 ACRE 0.0460 ACRE 0.0000 ACRE 0.1607 ACRE COMPOSITE "c" = 0.55 "c" Value = 0.9 "c" Value = 0.85 "c" Value = 0.45 DETENTION REQUIRED (BASED City of Austin Data) DURATION (HOURS) I (IN/HR) INFLOW STORED (CFS) (CFS) RESERVOIR (AC-FT) 12.5000 1.421 0.835 0.0058 MAX 0.0833 0.2500 0.5000 1.0000 2.0000 3.0000 6.0000 6.0800 0.691 0.105 2.4600 0.2797 -0.3063 4.3700 0.497 -0.089 2.8300 0.322 -0.264 2.0400 0.232 -0.354 1.1400 0.130 -0.456 12.0000 0.8060 0.092 -0.494 24.0000 0.5640 0.064 -0.522 0.0022 -0.0128 -0.0074 -0.0440 -0.0885 -0.2282 -0.4943 -1.0437