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Hubble - Opposed - 04-27-2021SPIN MEETING 04/27/2021 SPIN2021-09 • 1 am concerned that this development will add additional stormwater volumes to the West Jones Creek watershed due to increased runoff from the developed site. I am concerned that even if new retention is added to hold peak runoffs at current levels the increased volume of runoff will still cause higher levels of downstream erosion due to the extended drainage times and higher total runoff volume. • The outlet channels from the ponds at the City of Southlake's Gateway Park are experiencing high levels of erosion. The channels do not meet design criteria specified in City of Southlake's ordinance ARTICLE II. - STORM DRAINAGE POLICY: Sec. 9.5-61. - Drainage manual reference. (a) Fort Worth Drainage Manual or Sec. 9.5-65. - Miscellaneous design criteria DIVISION 4. - OPEN CHANNEL POLICY Sec. 9.5-82. - Natural channels or Sec. 9.5-83. - Earth channels. • The drainage channel at the outlet of the North Kimball Ave drainage culvert at approximately STA -30 is also experiencing high levels of erosion. This channel does not meet design criteria specified in City of Southlake's ordinance ARTICLE II. - STORM DRAINAGE POLICY: Sec. 9.5-61. - Drainage manual reference. (a) Fort Worth Drainage Manual or Sec. 9.5-65. - Miscellaneous design criteria DIVISION 4. - OPEN CHANNEL POLICY Sec. 9.5-82. - Natural channels or Sec. 9.5-83. - Earth channels. • Numerous projects have been approved and completed that add significantly to the Stormwater runoff since the last West Jones Creek watershed modeling/analysis. Last LOMR Feb 15, 2007, Last modeling of West Jones Creek watershed 2008 as part of Gateway Project. The above issues have been documented in a letter to the City on Feb. 22, 2019. No answer has been received to date. An engineering study of the areas noted above is currently being conducted by the Patterson Pond HOA. • Since the current water shed volumes already exceed the capacity of the above described facilities, in accord with City of Southlake ordinance Article 11 Storm Drainage Policy an updated West Jones Creek drainage study should be completed. Remedies for downstream drainage channels deficiencies should be agreed before this project is approved. • 1 cannot support this development unless a downstream study of the West Jones Creek watershed is done and the design deficiencies in the downstream channels are addressed. Signed by: He 80Hubble 2208 Patterson Way Southlake, Texas 76092 Phone: 817-424-9098