Recommendation 20241204-002: Dredge of Channel Rd. Lagoon — original pdf

Recommendation

1 ENVIRONMENTAL COMMISSION RECOMMENDATION 20241204-002 Date: December 4, 2024 Subject: Dredge of Channel Rd. Lagoon, SP-2023-0376D Motion by: Jennifer Bristol WHEREAS, the Environmental Commission recognizes the applicant is requesting to vary from LDC 25-8-261(C)(9)(a) to allow more than 25 cubic yards of dredging in Lake Austin; and WHEREAS, the Environmental Commission recognizes the site is located in Lake Austin Watershed Water Supply Rural Classification, Desired Development Zone; and WHEREAS, the Environmental Commission recognizes that Staff recommends the variance with the following conditions: Seconded by: Perry Bedford 1. Protect the natural shoreline areas and larger wetland Critical Environmental Feature (CEF) W-13 by providing a 3:1 H:V slope from the lake bottom elevation at the shoreline to the final dredge depth. 2. Provide additional wetland mitigation plantings (2,125 plantings comprised of an equal number of 6 different species of FACW and OBL species) within 5 feet of the shoreline to a maximum depth of 1 foot. 3. Provide additional wetland mitigation plantings (1,321 plantings comprised of an equal number of 6 different species of FAC and FACW species) on the other 14 existing wetland CEFs on land. 4. Restore all areas disturbed in the Critical Water Quality Zone (CWQZ) per Standard Specification 609S.) 5. Limit dredging within the 25% and 50% Critical Root Zones (CRZ) of trees along the shoreline to outside of the existing concrete retaining walls. 6. Provide measures to minimize/avoid sediment discharge including: 1) stabilized construction entrance and access road from the Channel Rd entrance to the barge access location and, 2) silt fencing and mulch logs downslope of staging, storage and dewatering areas, and 3) stabilized dewatering area for dredge bags, 4) floating turbidity curtain downstream of the dewatering operation, and 5) floating turbidity curtain surrounding active dredge area. 7. Conduct dredging via hydraulic methods using floating excavator units and bagging of material. THEREFORE, the Environmental Commission recommends the variance request with the following conditions; 1. Supply information about best practices in maintaining the plants and avoiding using chemicals that cause Algae blooms. Each of the property owners will receive a packet that includes the Go Green manual. 2. Find a way to reuse the sediment after it is dried and evaluated for toxins. VOTE 7-0 For: Haris Qureshi, Mariana Krueger, Hanna Cofer, Perry Bedford, Jennifer Bristol, Melinda Schiera, David Sullivan Against: None Recuse: None Absent: Richard Brimer and Colin Nickells Approved By: Perry Bedford, Environmental Commission Chair 2