B-09 (SPC-2012-0414C(R1) - Davis WTP Zebra Mussels Mitigation; District 10) — original pdf

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Development Services Department Staff Recommendations Concerning Required Findings Project Name & Case Number: Davis Water Treatment Plant - SPC-2012-0414(R1) Ordinance Standard: Watershed Protection Ordinance Variance Request: To allow construction within 150-foot Critical Environmental Feature (CEF) buffer for a Rimrock CEF [LDC 25-8-281(C)(2)(b)]. Include an explanation with each applicable finding of fact. A. Land Use Commission variance determinations from Chapter 25-8-41 of the City Code: 1. 2. The requirement will deprive the applicant of a privilege available to owners of similarly situated property with approximately contemporaneous development subject to similar code requirements. Yes. Other City of Austin water treatment plants have the same chemical feed system in place to help control zebra mussel infestations in the raw water transmission main. Chemical treatment is necessary to control zebra mussel infestations in raw water transmission mains. The variance: a) Is not necessitated by the scale, layout, construction method, or other design decision made by the applicant, unless the design decision provides greater overall environmental protection than is achievable without the variance; Yes. The variance is not necessitated by the design. No alternative locations are available on site for a Zebra Mussel Mitigation System. The system must be placed in or near the existing intake pump house. There is not enough room in the existing pump station to house the entire system, such as the chemical storage. All the proposed construction coincides within areas of existing impervious cover. Minimal impervious cover is being added. b) Is the minimum deviation from the code requirement necessary to allow a reasonable use of the property; Yes. The variance is a minimum deviation from the code requirement and is allowing for a reasonable use of the 1 of 20B-09property. No new impervious cover is proposed. The Zebra Mussel Mitigation System and the associated construction activities is in areas, or adjacent to areas, with existing impervious cover or development. The piping for the chemical storage and metering station is the shortest and most direct route to the existing building, and the system is located where there is already an asphalt driveway or development. c) Does not create a significant probability of harmful environmental consequences. Yes. The variance with the staff recommended conditions does not create a probability of significant harmful environmental consequences. Construction is within existing structures or where there is existing impervious cover. The chemical tank and piping are double contained. The equipment pad is curbed and covered with a canopy. The pump metering station includes a virtual day tank and there are automated valves at the pump bay that close if the pumps fail or when the pumps are not running. No new impervious cover is being added. As part of the Stormwater Pollution Prevention Plan, temporary sedimentation and erosion controls will be installed prior to the start of construction activities. The applicant is providing wetland plantings along the shoreline that will reduce shoreline erosion and reduce the possibility of sediment-laden surface runoff from entering the lake. 3. Development with the variance will result in water quality that is at least equal to the water quality achievable without the variance. Yes, the variance will result in water quality that is at least equal to the water quality achievable without the variance. The proposed construction will not impact existing water quality. No new impervious cover is proposed. During construction, Stormwater Pollution Prevention Plan best practices will be employed to prevent construction sediment and debris from entering the stormwater runoff, and additional wetland plants along the shoreline will be provided to enhance the water quality of surface water runoff. Staff Recommendation: Staff recommends the Findings of Fact have been met. B. The Land Use Commission may grant a variance from a requirement of Section 25-8- 422 (Water Supply Suburban Water Quality Transition Zone), Section 25-8-452 (Water Supply Rural Water Quality Transition Zone), Section 25-8-482 (Barton Springs Zone Water Quality Transition Zone), Section 25-8-368 (Restrictions on Development Impacting Lake Austin, Lady Bird Lake, and Lake Walter E. Long), or Article 7, Division 1 ( Critical Water Quality Zone Restrictions ), after determining that:   2 of 20B-09The criteria for granting a variance in Subsection (A) are met; Yes / No N/A Yes / No N/A The requirement for which a variance is requested prevents a reasonable, economic use of the entire property; 1. 2. 3. The variance is the minimum deviation from the code requirement necessary to allow a reasonable, economic use of the entire property. Yes / No N/A Staff Recommendation: N/A. Hydrogeologic Reviewer (WPD) __ Scott E. Hiers ________ Date: 4/07/2020 Environmental Officer (WPD) _____________________________ Chris Herrington Date: 4/07/2020 3 of 20B-09Development Services Department Staff Recommendations Concerning Required Findings Project Name: Ordinance Standard: Watershed Protection Ordinance Variance Request: Davis Water Treatment Plant - SPC-2012-0414(R1) Request to vary from LDC 25-8-341 to allow cut exceeding 4 feet, to 4.5 feet. Include an explanation with each applicable finding of fact. A. Land Use Commission variance determinations from Chapter 25-8-41 of the City Code: 1. The requirement will deprive the applicant of a privilege available to owners of similarly situated property with approximately contemporaneous development subject to similar code requirements. Yes Other City of Austin water treatment plants have the same chemical feed system in place to help control zebra mussel infestations in the raw water transmission main. Chemical treatment is necessary to control zebra mussel infestations in raw water transmission mains. 2. The variance: a) Is not necessitated by the scale, layout, construction method, or other design decision made by the applicant, unless the design decision provides greater overall environmental protection than is achievable without the variance; Yes The variance is not necessitated by the scale, layout, or construction method. It is necessitated by the steepness of the slope (40 percent) at the edge of the site where the concrete pad is proposed to be located. The cut is necessary for the concrete pad that will house the chemical feed system. The proposed pad location is 1) close to the freshwater intake, minimizing the amount of construction needed for laying the pipes; 2) outside of both the Critical Water Quality Zone for Lake Austin and the Water Quality Transition Zone for Huck’s Slough, maximizing distance from the adjacent bodies of water; and 3) on the far side of the site from the seep, spring, and rimrock Critical Environmental Features. 4 of 20B-09b) c) Is the minimum deviation from the code requirement necessary to allow a reasonable use of the property; Yes The variance is the minimum deviation from the code, exceeding the grading limit by only six inches. Does not create a significant probability of harmful environmental consequences. Yes The variance does not create a significant probability of harmful environmental consequences. The cut will be stabilized by a wall on three sides of the concrete pad. 3. Development with the variance will result in water quality that is at least equal to the water quality achievable without the variance. Yes The proposed construction will not impact existing water quality. During construction, erosion and sedimentation control best practices will be employed to prevent construction sediment and debris from entering the stormwater runoff. B. The Land Use Commission may grant a variance from a requirement of Section 25-8-422 (Water Supply Suburban Water Quality Transition Zone), Section 25-8-452 (Water Supply Rural Water Quality Transition Zone), Section 25-8-482 (Barton Springs Zone Water Quality Transition Zone), Section 25-8-368 (Restrictions on Development Impacting Lake Austin, Lady Bird Lake, and Lake Walter E. Long), or Article 7, Division 1 ( Critical Water Quality Zone Restrictions ), after determining that:: 1. The criteria for granting a variance in Subsection (A) are met; 2. 3. NA NA NA The requirement for which a variance is requested prevents a reasonable, economic use of the entire property; The variance is the minimum deviation from the code requirement necessary to allow a reasonable, economic use of the entire property. Staff Determination: Staff determines that the findings of fact have been met. No conditions are recommended. 5 of 20B-09Environmental Reviewer (DSD) ____________________________ (Pamela Abee-Taulli) 4/3/2020 Date Environmental Review Manager (DSD) _____________________________ (Mike McDougal) 4-3-2020 Date Environmental Officer (WPD) _____________________________ (Chris Herrington) 4/07/2020 ________________ Date 6 of 20B-09ENVIRONMENTAL COMMISSION VARIANCE APPLICATION FORM PROJECT DESCRIPTION Applicant Contact Information Name of Applicant Minda Sarmiento, Austin Public Works 6800 Burleson Road, Bldg 312, Ste 200 Street Address City State ZIP Code Work Phone E-Mail Address Case Name Case Number Address or Location Variance Case Information Austin, Texas 78744 512-974-5645 minda.sarmiento@austintexas.gov Davis WTP Zebra Mussels Mitigation SPC-2012-0414C(R1) 3352 Mount Bonnell Road Environmental Reviewer Name Pamela Abee-Taulli Environmental Resource Management Reviewer Name Scott Hiers Applicable Ordinance Watershed Name Watershed Classification Watershed Protection Ordinance Lake Austin; Huck’s Slough ☐Urban Water Supply Rural ☐ Suburban ☐Water Supply Suburban ☐ Barton Springs Zone Edwards Aquifer Recharge Zone ☐ Barton Springs Segment ☐ Not in Edwards Aquifer Zones Northern Edwards Segment Edwards Aquifer Contributing Zone ☐ Yes ☐No 7 of 20B-09Distance to Nearest Classified Waterway 100’ Water and Waste Water service to be provided by Not Applicable Request Impervious cover square footage: acreage: percentage: Provide general description of the property (slope range, elevation range, summary of vegetation / trees, summary of the geology, CWQZ, WQTZ, CEFs, floodplain, heritage trees, any other notable or outstanding characteristics of the property) The variance request is as follows (Cite code references): Land Development Code 25-8-281: Construction is prohibited within 150’ of a Critical Environmental Feature (in our case, rimrock and wetlands) Existing ________ ___7.31_____ ___27%_____ Proposed ____0_____ ____0_____ ____0_____ The site terrain slopes (~22%) towards the site parking lot and is located in the Lake Austin and Huck’s Slough Watersheds. The chemical metering station will be installed at an elevation of ~512’ and the chemical piping will be installed under the asphalt parking area. The terrain is covered with brush. There is one heritage tree: a 64’ diameter CRZ heritage oak tree located outside of the LOC at an elevation higher than the proposed work ground, although the dripline extends over the LOC. The chemical metering station will be installed outside of the WQTZ and CWQZ but, the chemical piping will have to cross through the CWQZ in order to reach the pump station. The concrete pad abuts a brush-covered slope and the back of the concrete pad will require excavation of 5.5’ of soil, exceeding the Land Development Code (LDC) limit of 4’ of excavation. There is rimrock and wetlands adjacent to the LSPS so the proposed installation will be located inside of the 150’ rimrock and wetlands CEF buffer. No work is proposed inside the 100-year floodplain. There are two identified wetlands areas on either side of the LSPS right at the shoreline. The wetlands will not be impacted by the proposed construction. 8 of 20B-09Clearly indicate in what way the proposed project does not comply with current Code (include maps and exhibits) • Construction will be performed within the 150’ rimrock/wetlands CEF buffer. FINDINGS OF FACT As required in LDC Section 25-8-41, in order to grant a variance the Land Use Commission must make the following findings of fact: Include an explanation with each applicable finding of fact. Project: Zebra Mussel Mitigation Techniques – Chemical Storage and Feed System Ordinance: A. Land Use Commission variance determinations from Chapter 25-8-41 of the City Code: 1. The requirement will deprive the applicant of a privilege available to owners of similarly situated property with approximately contemporaneous development subject to similar code requirements. The proposed construction prevents zebra mussels from clogging the LSPS of Yes the water treatment plant. All water plants with LSPSs drawing water from zebra mussel infested water bodies will require treatment to prevent zebra mussels from settling on the pump intake equipment and piping. If there is no room in the existing pump station, then the new construction must be installed outdoors in protected areas adjacent to the lakeshore. 2. The variance: a) Is not necessitated by the scale, layout, construction method, or other design decision made by the applicant, unless the design decision provides greater overall environmental protection than is achievable without the variance; Yes The design decision to place the chemical storage and metering station next to the lakeshore is because the LSPS is already on the lakeshore. There is no other feasible location. b) Is the minimum deviation from the code requirement necessary to allow a reasonable use of the property; Yes The chemical storage and metering station was situated in a small space outside of either the CWQZ or WQTZ. The chemical piping was routed in the shortest and most direct route and does not disturb any vegetated areas. 9 of 20B-09Does not create a significant probability of harmful environmental consequences. Yes The chemical storage and metering station is designed to prevent any harmful environmental consequences. The tank and piping are double contained. The equipment pad is curbed and covered with a canopy. The pump metering station includes a virtual day tank and there are automated valves at each pump bay that automatically close if the pumps fail and whenever the pumps are not running. Development with the variance will result in water quality that is at least equal to the water quality achievable without the variance. Yes The proposed construction will not impact existing water quality. During construction, SWPPP best practices will be employed to prevent construction sediment and debris from entering the stormwater runoff. c) B. Additional Land Use Commission variance determinations for a requirement of Section 25-8-422 (Water Quality Transition Zone), Section 25-8-452 (Water Quality Transition Zone), Article 7, Division 1 (Critical Water Quality Zone Restrictions), or Section 25-8-368 (Restrictions on Development Impacting Lake Austin, Lady Bird Lake, and Lake Walter E. Long): The criteria for granting a variance in Subsection (A) are met; Yes Installing a utility line in the CWQZ is permitted per Article 7 Division 1 (D) as long as the utility line follows the most direct path to minimize disturbance, which is true for the proposed utility lines. The requirement for which a variance is requested prevents a reasonable, economic use of the entire property; Yes The chemical storage and metering station will prevent zebra mussels from clogging the pump intake equipment and piping. Without it, the City would have to constantly physically remove the zebra mussels settling on the equipment at great expense. The variance is the minimum deviation from the code requirement necessary to allow a reasonable, economic use of the entire property. Yes The variance requested is the minimum deviation necessary to allow reasonable, economic use of the entire property. The chemical storage and metering station will prevent zebra mussels from clogging the pump intake equipment and piping. Without it, the City would have to constantly physically remove the zebra mussels settling on the equipment at great expense. 3. 1. 2. 3. 10 of 20B-09ENVIRONMENTAL COMMISSION VARIANCE APPLICATION FORM PROJECT DESCRIPTION Applicant Contact Information Name of Applicant Minda Sarmiento, Austin Public Works 6800 Burleson Road, Bldg 312, Ste 200 Street Address City State ZIP Code Work Phone E-Mail Address Case Name Case Number Address or Location Variance Case Information Austin, Texas 78744 512-974-5645 minda.sarmiento@austintexas.gov Davis WTP Zebra Mussels Mitigation SPC-2012-0414C(R1) 3352 Mount Bonnell Road Environmental Reviewer Name Pamela Abee-Taulli Environmental Resource Management Reviewer Name Scott Hiers Applicable Ordinance Watershed Name Watershed Classification Watershed Protection Ordinance Lake Austin; Huck’s Slough ☐Urban Water Supply Rural ☐ Suburban ☐Water Supply Suburban ☐ Barton Springs Zone Edwards Aquifer Recharge Zone ☐ Barton Springs Segment ☐ Not in Edwards Aquifer Zones Northern Edwards Segment Edwards Aquifer Contributing Zone ☐ Yes ☐No 11 of 20B-09Distance to Nearest Classified Waterway 100’ Water and Waste Water service to be provided by Not Applicable The variance request is as follows (Cite code references): Request Land Development Code 25-8-341: Cuts on a tract of land may not exceed four feet of depth. Impervious cover square footage: acreage: percentage: Existing ________ ___7.31_____ ___27%_____ Proposed ____0_____ ____0_____ ____0_____ Provide general description of the property (slope range, elevation range, summary of vegetation / trees, summary of the geology, CWQZ, WQTZ, CEFs, floodplain, heritage trees, any other notable or outstanding characteristics of the property) The site terrain slopes (~22%) towards the site parking lot and is located in the Lake Austin and Huck’s Slough Watersheds. The chemical metering station will be installed at an elevation of ~512’ and the chemical piping will be installed under the asphalt parking area. The terrain is covered with brush. There is one heritage tree: a 64’ diameter CRZ heritage oak tree located outside of the LOC at an elevation higher than the proposed work ground, although the dripline extends over the LOC. The chemical metering station will be installed outside of the WQTZ and CWQZ but, the chemical piping will have to cross through the CWQZ in order to reach the pump station. The concrete pad abuts a brush-covered slope and the back of the concrete pad will require excavation of 5.5’ of soil, exceeding the Land Development Code (LDC) limit of 4’ of excavation. There is rimrock and wetlands adjacent to the LSPS so the proposed installation will be located inside of the 150’ rimrock and wetlands CEF buffer. No work is proposed inside the 100-year floodplain. There are two identified wetlands areas on either side of the LSPS right at the shoreline. The wetlands will not be impacted by the proposed construction. 12 of 20B-09Clearly indicate in what way the proposed project does not comply with current Code (include maps and exhibits) • The back of the concrete pad will require 5.5’ of soil excavation. LDC limits excavation to a depth of 4’. FINDINGS OF FACT As required in LDC Section 25-8-41, in order to grant a variance the Land Use Commission must make the following findings of fact: Include an explanation with each applicable finding of fact. Project: Zebra Mussel Mitigation Techniques – Chemical Storage and Feed System Ordinance: A. Land Use Commission variance determinations from Chapter 25-8-41 of the City Code: 1. The requirement will deprive the applicant of a privilege available to owners of similarly situated property with approximately contemporaneous development subject to similar code requirements. The proposed construction prevents zebra mussels from clogging the LSPS of Yes the water treatment plant. All water plants with LSPSs drawing water from zebra mussel infested water bodies will require treatment to prevent zebra mussels from settling on the pump intake equipment and piping. If there is no room in the existing pump station, then the new construction must be installed outdoors in protected areas adjacent to the lakeshore. 2. The variance: a) Is not necessitated by the scale, layout, construction method, or other design decision made by the applicant, unless the design decision provides greater overall environmental protection than is achievable without the variance; Yes The design decision to place the chemical storage and metering station next to the lakeshore is because the LSPS is already on the lakeshore. There is no other feasible location. b) Is the minimum deviation from the code requirement necessary to allow a reasonable use of the property; Yes The chemical storage and metering station was situated in a small space outside of either the CWQZ or WQTZ. The chemical piping was routed in the shortest and most direct route and does not disturb any vegetated areas. 13 of 20B-09Does not create a significant probability of harmful environmental consequences. Yes The chemical storage and metering station is designed to prevent any harmful environmental consequences. The tank and piping are double contained. The equipment pad is curbed and covered with a canopy. The pump metering station includes a virtual day tank and there are automated valves at each pump bay that automatically close if the pumps fail and whenever the pumps are not running. Development with the variance will result in water quality that is at least equal to the water quality achievable without the variance. Yes The proposed construction will not impact existing water quality. During construction, SWPPP best practices will be employed to prevent construction sediment and debris from entering the stormwater runoff. c) B. Additional Land Use Commission variance determinations for a requirement of Section 25-8-422 (Water Quality Transition Zone), Section 25-8-452 (Water Quality Transition Zone), Article 7, Division 1 (Critical Water Quality Zone Restrictions), or Section 25-8-368 (Restrictions on Development Impacting Lake Austin, Lady Bird Lake, and Lake Walter E. Long): The criteria for granting a variance in Subsection (A) are met; Yes Installing a utility line in the CWQZ is permitted per Article 7 Division 1 (D) as long as the utility line follows the most direct path to minimize disturbance, which is true for the proposed utility lines. The requirement for which a variance is requested prevents a reasonable, economic use of the entire property; Yes The chemical storage and metering station will prevent zebra mussels from clogging the pump intake equipment and piping. Without it, the City would have to constantly physically remove the zebra mussels settling on the equipment at great expense. The variance is the minimum deviation from the code requirement necessary to allow a reasonable, economic use of the entire property. Yes The variance requested is the minimum deviation necessary to allow reasonable, economic use of the entire property. The chemical storage and metering station will prevent zebra mussels from clogging the pump intake equipment and piping. Without it, the City would have to constantly physically remove the zebra mussels settling on the equipment at great expense. 3. 1. 2. 3. 14 of 20B-09CITY OF AUSTIN DAVIS WTP ZEBRA MUSSEL CHEMICAL STORAGE AND FEED SYSTEM (8207.009) Project Location Map Legend ^* DAVIS WTP / 0 Feet 800 800 1 inch = 1,700 feet BV PN 402943/198493 ^* OveriewUllrichWTPZebraMusselChemicalStorage&FeedSystem February 07, 2020 Edit this text with your name under File --> Map Document Properties --> Author 15 of 20B-092 FEMA 100 YR FLOODPLAIN 2 CITY OF AUSTIN FULLY DEVELOPED FLOODPLAIN C E F F E C CHEMICAL STORAGE AND METERING LAYOUT DAVIS LSPS g w d i . s v a D - 6 0 - G 8 7 2 8 0 9 0 d \ \ s a c i r e m a _ w v b \ i g n k r o w _ w p \ : C : I E L F M A 6 0 : 8 0 2 0 2 4 / / 3 : D E T T O L P A 0 0 0 9 D F 0 0 0 0 1 D 20' 10' 0' 20' 40' SCALE 1"=20' LEGEND CRITICAL WATER QUALITY ZONE WATER QUALITY TRANSITION ZONE 2 CRITICAL ENVIRONMENTAL FEATURE: WETLANDS CEF CRITICAL ENVIRONMENTAL FEATURE (CANYON RIMROCK)* CREEK ROCK OUTCROPS SEEPS AND SPRINGS SEEPS AND SPRINGS P P A K H C Y B . O N E S U F O D R O C E R D N A S N O S V E R I I E T A D 1 2 ) D N U O R G K C A B D E T A D P U ( 1 . O N M U D N E D D A / 0 2 0 2 0 1 1 0 / 2 . O N M U D N E D D A 0 2 0 2 3 0 / / 3 0 I I S E U Q N H C E T N O T A G T M L E S S U M A R B E Z I I I N T S U A F O Y T C I P T W S V A D I L A R E N E G T U O Y A L E T S I DESIGNED: MLS DETAILED: BWA CHECKED: AVK APPROVED: DAT DATE: NOVEMBER 2019 0 1/2 1 IF THIS BAR DOES NOT MEASURE 1" THEN DRAWING IS NOT TO FULL SCALE PROJECT NO. 402943 G-06 SHEET 36 6 OF © 2019 Microsoft Corporation © 2019 DigitalGlobe ©CNES (2019) Distribution Airbus DS (cid:1)3/3/2020CHRIS P. DORMIER87689STATE OFTEXASLICENSEDPROFESSIONALENGINEER16 of 20B-09Z Q W C 64' DIAMETER HERITAGE OAK TREE (MULTI-TRUNK) DRIPLINE LOC CHEMICAL STORAGE AND METERING LAYOUT. SEE SHEET M-03 FG 514.5' 2 FG 514.5' Z T Q W T P 3 L O C T P LOC 2 2 1-1/2" GATE VALVE W S 5 STA 0+02 90 DEG BEND TYP OF 6 6 STA 0+08 90 DEG BEND TYP OF 6 7 STA 0+09 90 DEG BEND TYP OF 6 APPROX. TOP OF EXISTING DUCTBANK - 505'. CONTRACTOR TO CONFIRM IN FIELD. FG 511.5' 1 8 STA 0+17 45 DEG BEND TYP POF 6 MATCH PIPE INVERT TO TOP OF PAVEMENT BOLLARD (TYP OF 5) B C-03 Z Q W C STAGING AREA Z T Q W S 4 FG 511.5' 5 1 6 5 1 5 5 1 4 C O L 5 1 3 S 512 S MH2 5' 3' 0" 5' 10' SCALE 1"=5' NOTES: 5 1 7 1. CONTRACTOR TO ADJUST EROSION CONTROL AS REQUIRED FOR FIELD CONDITIONS TO MEET THE INTENT OF THE CONSTRUCTION DOCUMENTS. 2. ALL SEDIMENT SPILLED, DROPPED, WASHED, OR TRACKED ONTO ROADWAY MUST BE REMOVED IMMEDIATELY BY THE CONTRACTOR. 3. ENVIRONMENTAL INSPECTOR HAS THE AUTHORITY TO ADD AND/OR MODIFY EROSION/SEDIMENTATION CONTROLS ON SITE TO KEEP PROJECT IN COMPLIANCE WITH THE CITY OF AUSTIN RULES AND REGULATIONS. 4. CONTRACTOR SHALL UTILIZE DUST CONTROL MEASURES (PER ECM 1.4.8.C.) DURING SITE CONSTRUCTION SUCH AS IRRIGATION TRUCKS AND MULCHING OR AS DIRECTED BY THE ENVIRONMENTAL INSPECTOR. 5. IF DISTURBED AREA IS NOT TO BE WORKED ON FOR MORE THAN 14 DAYS, DISTURBED AREA NEEDS TO BE STABILIZED BE MULCH, TARP OR REVEGETATION. 6. PRIOR TO EXCAVATION WITHIN TREE DRIP LINES, OR THE REMOVAL OF OTHER TREES THAT ARE TO REMAIN, MAKE A CLEAN CUT BETWEEN THE DISTURBED AND UNDISTURBED ROOT ZONES WITH A ROCK SAW OR SIMILAR EQUIPMENT TO MINIMIZE ROOT DAMAGE. A) IN CRITICAL ROOT ZONE AREAS THAT CANNOT BE PROTECTED DURING CONSTRUCTION WITH FENCING, AND WHERE HEAVY VEHICULAR TRAFFIC IS ANTICIPATED, COVER THOSE AREAS WITH FOUR (4) INCHES OF ORGANIC MULCH TO BE PRODUCED ON SITE, TO MINIMIZE SOIL COMPACTION. B) PERFORM ALL GRADING WITHIN CRITICAL ROOT ZONE AREAS WITH SMALL EQUIPMENT TO MINIMIZE ROOT DAMAGE. C) WATER ALL TREES MOST HEAVILY IMPACTED BY CONSTRUCTION ACTIVITIES DEEPLY AS NECESSARY DURING PERIOD OF HOT, DRY WEATHER. SPRAY TREE CROWNS WITH WATER PERIODICALLY TO REDUCE DUST ACCUMULATION ON THE LEAVES. D) WHEN INSTALLING CONCRETE ADJACENT TO THE ROOT ZONE OF A TREE, USE A PLASTIC VAPOR BARRIER BENEATH THE CONCRETE TO PROHIBIT LEACHING OF LIME INTO THE SOIL. THE STAGING AND SPOILS AREA SHALL ONLY BE ALLOWED DURING THE CONSTRUCTION PERIOD. NO SPOILS SHALL REMAIN STAGED AFTER COMPLETION OF THE PROJECT. ALL DISTURBED AREAS SHALL BE REVEGETATED WITH NATIVE GRASSES (REFER TO APPENDIX P-1 ON GENERAL NOTES SHEET FOR SPECS). ALL DISTURBED AREAS WITH SLOPES 5:1 OR STEEPER, WHICH ARE NOTE ARMORED OTHERWISE, SHALL HAVE A SOIL RETENTION BLANKET (CURLEX II OR APPROVED EQUAL) INSTALLED TO ASSIST WITH REVEGETATION. 7. 8. 9. RESTORE ASPHALT PAVEMENT PER DETAIL 510S-3 ON SHEET C-02. 10. ELEVATIONS AND CONTOURS FOR THIS PROJECT ARE BASED ON CITY OF AUSTIN REFERENCE POINT "NO. 3003" A CITY OF AUSTIN BRASS DISK MONUMENT ON TOP OF CURB ON THE WEST SIDE OF FUNSTON STREET NORTH OF THE INTERSECTION OF FUNSTON STREET AND 33RD STREED, 25 FEET NORTH OF THE NORTH END OF THE CURB RETURN ON THE NORTH SIDE OF THE DRIVEWAY FOR THE HOUSE AT 3302 FUNSTON STREET. (NAVD 88) ELEVATION = 610.34 FEET. 10087597.93 3103824.85 CONCRETE PAD LEGEND NORTHING AND EASTING TABLE OF FITTINGS AND STRUCTURES NO. NORTHING EASTING DESCRIPTION 10087578.45 3103825.19 CONCRETE PAD 10087598.42 3103852.18 CONCRETE PAD 10087578.94 3103852.51 CONCRETE PAD 10087588.22 3103826.91 90 DEGREE BEND 10087581.65 3103827.02 45 DEGREE BEND 10087580.59 3103828.12 45 DEGREE BEND 10087572.63 3103828.26 45 DEGREE BEND 10087533.53 3103790.33 45 DEGREE BEND *NORTHING AND EASTINGS REPRESENT THE CENTERLINE OF THE MIDDLE PIPE 1 2 3 4 5 6 7 8 9 CRITICAL WATER QUALITY ZONE WATER QUALITY TRANSITIONAL ZONE 2 LIMITS OF CONSTRUCTION CWQZ WQTZ LOC W EOP S TFD TP FG TOC POTABLE WATER EDGE OF PAVEMENT SILT FENCE TRIANGULAR FILTER DYKE TREE PROTECTION FINISHED GRADE TOP OF CONCRETE FLOW ARROW 5 1 1 Z T Q W COORDINATE USE OF STAGING AREA WITH ANY CONTRACTORS ALREADY ON-SITE T F D P P A K H C Y B . O N E S U F O D R O C E R D N A S N O S V E R I I E T A D 1 2 ) D N U O R G K C A B D E T A D P U ( 1 . O N M U D N E D D A 0 2 0 2 0 1 / / 1 0 2 . O N M U D N E D D A 0 2 0 2 3 0 / / 3 0 I I S E U Q N H C E T N O T A G T M L E S S U M A R B E Z I I I N T S U A F O Y T C I P T W S V A D I N A L P T U O Y A L E T S I I L V C I DESIGNED: MLS DETAILED: BWA CHECKED: AVK APPROVED: DAT DATE: NOVEMBER 2019 0 1/2 1 IF THIS BAR DOES NOT MEASURE 1" THEN DRAWING IS NOT TO FULL SCALE PROJECT NO. 402943 C-01 SHEET 36 7 OF 517 516 515 514 513 2 C O L 1-1/2" W - TYPE 4 COPPER W S MH1 S W W C O L S S APPROX. TOP OF EXISTING DUCTBANK - 506'. CONTRACTOR TO CONFIRM IN FIELD. W SIX 1" INSIDE 3" DOUBLE-CONTAINED SCH 80 PVC PIPE A C-03 T F D 2 9 STA 0+72 45 DEG BEND TYP OF 6 SEE DETAILS ON SHEET M-01 FOR WALL PIPE PENETRATION DETAIL REPLACE CONCRETE SIDEWALK PER DETAIL 432S-1 ON SHEET C-02 ASPHALT PAVEMENT 8" RW-DI RISER DAVIS WTP LSPS Z Q W C Z Q W C g w d i . s v a D - 1 0 - C 7 8 2 8 0 9 0 d \ \ s a c i r e m a _ w v b \ i g n k r o w _ w p \ : C : I E L F M A 4 3 : 7 0 2 0 2 3 / / 3 : D E T T O L P A 0 0 0 9 D F 0 0 0 0 1 D FLOODPLAIN NOTES: THIS PROJECT IS LOCATED WITHIN UNSHADED ZONE 'X' OF THE FLOOD INSURANCE RATE MAP NO. 48453C0435K, WHICH BEARS AN EFFECTIVE DATE OF JANUARY 22, 2020 AND DOES NOT LIE WITHIN A SPECIAL FLOOD HAZARD AREA. NO FIELD SURVEY WAS PERFORMED TO DETERMINE THIS ZONE AND AN ELEVATION CERTIFICATE MAY BE NEEDED TO VERIFY THIS DETERMINATION OR APPLY FOR A VARIANCE FROM THE FEDERAL EMERGENCY MANAGEMENT AGENCY. (cid:1)3/3/2020CHRIS P. DORMIER87689STATE OFTEXASLICENSEDPROFESSIONALENGINEER17 of 20B-09MT BO NNELL RD L O C BRID GE C L O L O C L O C L O C M T B O N N E L L R D C LO C O L L O C 2 Z Q W C CRITICAL ENVIRONMENTAL FEATURE: RIMROCK Z T Q W C E F C E F AC CESS R O AD (ASPHALT) LO C LO C HERITAGE TREE - NOTE 2 QTZ W CHEMICAL STORAGE AND METERING LOC T P S C W Q Z C O L S S Z T Q W COORDINATE LIMITS OF TRIDIKE WITH CONTRACTORS METHODS AND ENVIRONMENTAL INSPECTOR INSTALL CONCRETE WASHOUT. SEE NOTE 3. T F D C W Q Z L O C C W Q Z 2 100 YR FLOODPLAIN (FEMA) FULLY DEVELOPED FLOODPLAIN (CITY OF AUSTIN FLOODPLAIN MODEL) g w d i - . s v a D A 1 0 - C 7 8 2 8 0 9 0 d \ \ s a c i r e m a _ w v b \ i g n k r o w _ w p \ : C : I E L F M A 2 2 : 7 0 2 0 2 / 4 / 3 : D E T T O L P 0 0 0 0 1 D F 0 0 0 0 1 D P P A K H C Y B . O N E S U F O D R O C E R D N A S N O S V E R I I E T A D 1 2 ) D N U O R G K C A B D E T A D P U ( 1 . O N M U D N E D D A 0 2 0 2 0 1 / / 1 0 2 . O N M U D N E D D A 0 2 0 2 3 0 / / 3 0 I I S E U Q N H C E T N O T A G T M L E S S U M A R B E Z I I I N T S U A F O Y T C I P T W S V A D I L I V C I I N O T C U R T S N O C F O S T M I L I , S S E C C A E T S L L A R E V O I I N A L P L O R T N O C N O T A T N E M D E S D N A N O S O R E D N A I I DESIGNED: MLS DETAILED: BWA CHECKED: AVK APPROVED: DAT DATE: NOVEMBER 2019 0 1/2 1 IF THIS BAR DOES NOT MEASURE 1" THEN DRAWING IS NOT TO FULL SCALE PROJECT NO. 402943 C-01A 36 7A SHEET OF 30' 15' 0' 30' 60' SCALE 1"=30' NOTES: 1. CONSTRUCTION EXIT NOT REQUIRED AS NO TRUCK TIRES LEAVE THE PAVEMENT. 2. LIVE OAK TREE WITH 32" DIAMETER MULTI-TRUNK AND A 64' DIAMETER DRIPLINE IS LOCATED OVER 25' ABOVE CONSTRUCTION AREA. COORDINATE NEED FOR TREE PROTECTION WITH ENVIRONMENTAL INSPECTOR. 3. CONTRACTOR SHALL COORDINATE LOCATION OF CONCRETE WASH OUT AREAS WITH ENVIRONMENTAL INSPECTOR IN FIELD. CONTRACTOR SHALL SUBMIT DETAILS OF PROPOSED WASH OUT DESIGN AND LOCATIONS TO ENGINEER FOR REVIEW AND APPROVAL. 2 4. ALL SPOILS ARE TO BE PLACED BACK IN TRENCH EVERY NIGHT; OR IF SPOILS ARE TO REMAIN OVERNIGHT, SPOILS MUST BE PLACED ON THE UPHILL SIDE OF TRENCH WITHIN THE LOC. 5. PERPENDICULAR EROSION CONTROLS MUST BE INSTALLED EVERY 30 FEET AS THE TRENCH IS BACKFILLED. LEGEND CWQZ WQTZ LOC EOP S TFD TP CEF CRITICAL WATER QUALITY ZONE WATER QUALITY TRANSITIONAL ZONE LIMITS OF CONSTRUCTION EDGE OF PAVEMENT SILT FENCE TRIANGULAR FILTER DYKE TREE PROTECTION CRITICAL ENVIRONMENTAL FEATURE (CANYON RIMROCK) 2 CREEK WETLANDS CEF BUFFER ZONE SEEPS AND SPRINGS (cid:1)3/3/2020CHRIS P. DORMIER87689STATE OFTEXASLICENSEDPROFESSIONALENGINEER18 of 20B-09 ENVIRONMENTAL COMMISSION MOTION 20200415 006c Date: April 15, 2020 Subject: Davis Water Treatment Plant, SPC-2012-0414(R1) Motion by: Kevin Ramberg Seconded by: Katie Coyne RATIONALE: WHEREAS, the Environmental Commission recognizes the applicant is requesting a variance from LDC 25- 8-281 (C)(2)(b) to allow construction within the 150-foot buffer of Critical Environmental Features. WHEREAS, the Environmental Commission recognizes the applicant is requesting a variance from LDC 25- 8-341 to allow cut exceeding 4 feet, to 5.5 feet. WHEREAS, the Environmental Commission recognizes that staff recommend the variance without conditions having determined the findings of fact have been met. THEREFORE, the Environmental Commission recommends approval of the requested variances from LDC 25-8-281 (C)(2)(b) to allow construction within the 150-foot buffer of Critical Environmental Features and LDC 25-8-341 to allow cut to 5.5 feet with the following; Staff Conditions: None Environmental Commission Conditions: None VOTE 9-0 For: Smith, Nill, Neely, Gordon, Bedford, Ramberg, Guerrero, Coyne, and Maceo Against: None Abstain: None Recuse: None Absent: Creel, Thompson 1 19 of 20B-09 Approved By: Linda Guerrero, Environmental Commission Chair 2 20 of 20B-09