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HomeMy WebLinkAbout20070205 - VIII-B-5VIII-B-S Memo To: Mayor Hicks and City Council From: John Hinzman, Planning Director Date: February 5, 2007 Subject: Approve Stormwater Management Plan -SUP #2005-23 ConAgra Floodwall - SACC Group (2005 Vermillion Street) REQUEST The City Council is asked to approve the stormwater management plan for the construction of the ConAgra floodwall at 2005 Vermillion Street. Review of the plan was required as part of the Special Use Permit approval of August 1, 2005. The City Council voted to table this item at the September 19, 2005 City Council meeting in order prepare a more comprehensive storm water management plan for the entire site. Please see attached City Council Minutes for further information. SWPP Plan A Stormwater Pollution Prevention (SWPP) Plan has been developed for the entire ConAgra site. The SWPP plan requires the identification of all erosion and sediment control measures and best management practices as well as existing and cumulative effects on stormwater volume and condition. RECOMMENDATION The City's consultant engineer, John Stewart has reviewed the SWPP plan and recommends approval. The plan has also been reviewed and approved by Jim Davidson of the Dakota County Soil and Water Conservation District. Approval is recommended subject to the following conditions: Divert stormwater flows from roof drains, upland areas etc around the construction site and other exposed soils to reduce sediment transport to the sediment barrier and reduce the overall volume of runoff requiring treatment at the sediment basin. 2. The sediment basin capacity and outlet design shall comply with NPDES Permit Part III.B requirements. The discharge flow out of the sediment basin shall not exceed the VRWJPO 50 NTU turbidity standard. Additional water treatment BMPs (or other measures necessary) shall be promptly implemented to correct discharge turbidity greater than 50 NTU. ATTACHMENTS • SWPP Plan • Stormwater Maps • City Council Minutes -September 19, 2005 Stormwater Pollution Prevention Plan (SWPPP) ConAgra Food Ingredients Hastings, MN Construction Activity Information Project Name Boiler Room Bank Stabilization & Retaining Wall -ConAgra Foods Food Ingredients Company, Inc. Project Location Briefly describe where construction activity occurs. Include address if available One Kin Midas Park City or Township Hastin s State, Zip Code MN 55803 Count Parcel ID # Attach list if necessary All cities where construction will occur Hastin s All counties where construction will occur Dakota All townships where construction will occur SW quarter of the NW quarter of Section 34 in Hastings fownshi Townshi #115, Ran a #17 Project Size number of acres to be disturbed 0.37 acres Project Type Residential Commercial/Industrial Road Construction Other describe Cumulative Impervious Surface Existing area of impervious surface _10.52 acres (to the nearest quarter acre) Post construction area of impervious surface 10.52 acres (to the nearest quarter acre) Receiving Waters Name of Water Body Type (ditch, pond, wetland, lake, stream, river) Appendix A special water? Vermillion River River Yes v No Yes No Yes No Yes No Dates of Construction Construction Start Date Jul 16, 2007 Estimated Completion Date October 12, 2007 Stormwater Pollution Prevention Plan -Bank Stabilization Project January 2007 ConAgra Food Ingredients Inc. Our File No. 207200 ConAgra Flour Milling Co. -Hastings, MN Page 1 of 10 Stormwater Pollution Prevention Plan (SWPPP) ConAgra Food Ingredients Hastings, MN Contact Information Owner of the Site Business of Firm Name Federal Tax ID State Tax ID ConAgra Foods Food 20-1248932 In redients Com an ,Inc Last Name First Name Title E-mail Telephone (include area Young, Terry Director of Terry.young@conagrafoods.com code) En ineerin (402)595-4404 Mailing Address City State Zip Code Nine ConA ra Drive Omaha NE 68102 Alternate Contact Last Name First Name E-mail Telephone (include area Hoernin Dean dean.hoernin cona rafoods.com code) 402 595-4237 Contractor Person who will oversee im lementation of the SWPPP Business of Firm Name Federal Tax ID State Tax ID SACC Grou Inc. 98 - 0368252 5970079 Last Name First Name Title E-mail Telephone (include area Sacchetti, Paolo Project info@saccgroup.com code) Mana er (218) 727 - 5200 Mailing Address City State Zip Code 802 Garfield Ave. Duluth MN 55802 Alternate Contact Last Name First E-mail Telephone (include area Name info@saccgroup. com code) Sacchetti, Leon 807 344 - 4757 Party Responsible for Long Term Operation and Maintenance of the Permanent Stormwater Mana ement S stem Business of Firm Name Federal Tax ID State Tax ID ConAgra Foods Food 20-1248932 In redients Com an ,Inc Last Name First Name Title E-mail Telephone (include area Dillingham, Scott Plant Manager Scott.dillingham@conagrafoods.com code) 651 437 0149 Mailing Address City State Zip Code One Kin Midas Park Hastin s MN 55803 Alternate Contact Last Name First Name E-mail Telephone (include area Bance, Dave Dave.bance cona rafoods.com code) 651 437 3161 General Construction Project Information Describe the construction activity (what will be built, general timeline, etc.) A new concrete retaining wall will be built to stabilize the existing eroded /deteriorated limestone embankment between Vermillion River and ConAgra's Boiler Room Building. Work is scheduled fo start mid July 2007 (low water level) and be completed by mid October 2007. Stormwater Pollution Prevention Plan -Bank Stabilization Project January 2007 ConAgra Food Ingredients Inc. Our File No. 207200 ConAgra Flour Milling Co. -Hastings, MN Page 2 of 10 Stormwater Pollution Prevention Plan (SWPPP) ConAgra Food Ingredients Hastings, MN soil types found at the project. The primary material on site is limestone rock. There is ballast from the rail tracks and some course ravel over the existin limestone. General site information (IILA) Describe the location and type of all temporary and permanent erosion prevention and sediment control BMPs. Include the timing for installation and procedures used to establish additional temporary BMPs as necessary. (III.A.3.a) Work Schedule Because the new concrete retaining wall would be built on the shoreline of the Vermillion River (base of the existing embankment), the work would be scheduled in the summer (July) when the water is typically at its lowest levels /flows. Silt control measures would be installed along the shoreline to prevent silt, caused by construction operations, from entering the river. Silt Control Measures A precast concrete block wall (interlocked) would be installed along the shoreline to isolate the river from the worksite. These concrete blocks (approx. 2' wide X 2' high X 6' long) would be placed over geotextile fabric (fill void between base of precast blocks and uneven shoreline). Two (2) rows of blocks would be installed, effectively creating a 4' high cofferdam wall along the shoreline. The weight of the blocks (3,6001bs. each) would create adequate protection in the event of a flood or high water levels. The concrete block cofferdam would have a settling pond located at the downstream end (low point) so any silt collected within the cofferdam would settle and filter the water prior to seeping out into the river. In the event of a heavy rainfall, a dewatering plan would be implemented (See Section IV. D). This control measure would remain in place until the project was completed and the NOT (Notice of Termination) Form was submitted. Project Access & Staging Areas Project access would be from the north over Track No. 4 and 5 adjacent to `A' & `B' Mill Feed Loadout. The crane pad would be located on the top of the embankment, east of the Boiler Room Building, south of the track and west of the twin culvert outfall. Other staging areas include east of the twin culvert outfall and north of Track 4 in a fenced off area. The crane /staging area on the top of the embankment would have aheavy--duty silt curtain along the edge to prevent silt from flowing over the edge and falling into the river. A check dam would be installed at the end of the twin culvert outfall to prevent any silt from being discharged over the edge into the river. In the event of a heavy rainfall, a dewatering plan would be implemented (See Section IV.D). Please see attached Drawing D-2 -Plan During Construction Phase detailing the location of all silt curtains /barriers /check dam and Sketch A -1 illustrating across-section of the proposed silt barriers. Stormwater Pollution Prevention Plan -Bank Stabilization Project January 2007 ConAgra Food Ingredients Inc. Our File No. 207200 ConAgra Flour Milling Co. -Hastings, MN Page 3 of 10 Stormwater Pollution Prevention Plan (SWPPP) ConAgra Food Ingredients Hastings, MN Attach to this SWPPP a site map that includes the following features (III.A.3.b - f): • Existing and final grades, including dividing lines and direction of flow for all pre and post-construction stormwater runoff drainage areas located within the project limits. • Locations of impervious surfaces and soil types. • Location of areas of phased construction Please see the attached Drawing D-1 -Existing Drainage Conditions, Drawing D-2 -Plan During Construction Phase and D-3 -Final Drainage Plan. • Locations of areas not to be disturbed. Please see the attached Drawing SP-1-ConAgra Site Plan with Proposed Shoring along River Bank and SACC Group Drawing SP-2 -Close up of Site Plan for Drainage Conditions • All surface waters and existing wetlands within one-half mile from the project boundaries that will receive stormwater runoff from the site (identifiable on maps such as USGS 7.5 minute quadrangle maps or equivalent). Where surface waters receiving runoff associated with construction activity will not fit on the plan sheet, they must be identified with an arrow, indicating both direction and distance to the surface water. Please see the attached USGS 7.5-minute map of Hastings and marked-up Map Quest diagrams (Street Map & Aerial Photo) of the work site and surrounding bodies of water. • Methods to be used for final stabilization of all exposed soil areas. Not applicable Were stormwater mitigation measures required as the result of an environmental, archaeological, or other required local, state, or federal review of the project? If yes, describe how these measures were addressed in the SWPPP. (III.A.5.) Mitigation measures required by the city are addressed in submittals to the city are addressed in submittals to the city dated 8/22/05, 10/5/06, 10/25/06. These measures are substantially similar to the measures in this SWPPP. Is the project located in a karst area such that additional measures would be necessary to protect drinking water supply management areas as described in Minn. R. chapters 7050 and 7060? If yes, describe the additional measures to be used. (III.A.6.) Not applicable Stormwater Pollution Prevention Plan -Bank Stabilization Project January 2007 ConAgra Food Ingredients Inc. Our File No. 207200 ConAgra Flour Milling Co. -Hastings, MN Page 4 of 10 stormwater Pollution Prevention Plan (SWPPP) ConAgra Food Ingredients Hastings, MN Does the site discharge to an impaired water that has an approved TMDL implementation plan that contains requirements for construction stormwater discharges? (III.A.7) If yes, • Identify the receiving water and the areas of the site discharging to it • Describe the type and locations of BMPs that are appropriate for the site and sufficient to comply with all applicable requirements of the TMDL implementation plan Lower Vermillion River (downstream of the Old Mill Dam) is on the list of impaired waters for turbidity (303D). A precast concrete block wall (interlocked) would be installed along the shoreline to isolate the river from the worksite. These concrete blocks (approx. 2' wide X 2' high X 6' long) would be placed over geotextile fabric (fill void between base of precast blocks and uneven shoreline). Two (2) rows of blocks would be installed, effectively creating a 4' high cofferdam wall along the shoreline. The weight of the blocks (3,600 lbs. each) would create adequate protection in the event of a flood or high water levels. The concrete block cofferdam would have a settling pond located at the downstream end (low point) so any silt collected within the cofferdam would settle and filter the water prior to seeping out into the river. In the event of a heavy rainfall, a dewatering plan would be implemented (See Section IV. D). Selection of a Permanent stormwater Mana ement S stem IILC Will the project create a new cumulative impervious surface greater than or equal to one acre? Yes No If yes, a water quality volume of/2 inch of runoff from this area must be treated before leaving the site or entering surface waters (1 inch if discharging to special waters). Describe which method will be used to treat runoff from the new impervious surfaces created by the project (IILC): • Wet sedimentation basin • Infiltration/Filtration • Regional ponds • Combination of practices Include all calculations and design information for the method selected. See Part II.C of the permit for specific requirements associated with each method. The area behind the new concrete /precast block retaining wall is the new area that would be created by the project. This area would have a slope of 4 horizontal to 1 vertical. Geotexti/e fabric would be placed over the granular fill c/w a rip-rap cover (approx. 12" layer) to provide slope stabilization. Weeping file (6" dia.) c/w filter sock (at 6 foot intervals running perpendicular to the concrete wall back the existing rock face), would be installed approx. 24"below the sloped granular/ rip-rap area to capture most of the storm water filtration. Additional weeping file would be installed along the full length of the precast block wall (near base) & concrete wall at 10 foot intervals (horizontal) and 6 foot intervals (vertical) to further capture and channel the stormwater to the base of the retaining wall where weep holes were located. At each weep hole, a bed of crushed stone wrapped with geotextile fabric (approx. 2' X 2' X 12") would be added to prevent silt filtration into the river. Please see the attached storm water run-off study calculations prepared by Industrial Project stormwater Pollution Prevention Plan -Bank Stabilization Project January 2007 ConAgra Food Ingredients Inc. Our File No. 207200 ConAgra Flour Milling Co. -Hastings, MN Page 5 of 10 s~ormwa~er po~~u~ion prevention Plan (SWPPP) ConAgra Food Ingredients Hastings, MN Describe why it is not feasible to meet the treatment requirement for the water quality volume. This can include proximity to bedrock or road projects where the lack of right of way precludes the installation of any permanent stormwater management practices. Describe what other treatment, such as grasses swales, smaller ponds, or grit chambers, will be implemented to treat runoff prior to discharge to surface waters. (III.C) Not applicable If proposing an alternative method to treat runoff from the new impervious surfaces, describe how this alternative will achieve approximately 80% removal of total suspended solids on an annual average basis (III.C.5). NOTE: If proposing an alternative method, you must submit your SWPPP to MPCA at least 90 days prior to the starting date of the construction activity. Not applicable Erosion Prevention Practices IV.B Describe construction phasing, vegetative buffer strips, horizontal slope grading, and other construction practices to minimize erosion. Delineate areas not to be disturbed (e.g., with flags, stakes, signs, silt fence, etc.) before work begins. The existing sloped rock and portion of the rock face behind the new concrete /precast block retaining wall would be filled the granular material and covered with geotextile fabric c/w rip-rap (12"). No erosion would occur in this area. Please see attached Drawing D-2 -Plan During Construction Phase detailing the location of all silt curtains /barriers /check dam and Sketch A -1 illustrating across-section of the proposed silt barriers. Describe temporary erosion protection or permanent cover used for exposed positive slopes within 200 lineal feet of a surface water (see section IV.6.2 for maximum time an area can remain exposed based on slope steepness). Not applicable For drainage or diversion ditches, describe practices to stabilize the normal wetted perimeter within 200 lineal feet of the property edge or point of discharge to a surface water. The storm water diversion Swale to the check dam on the top of the rock (existing grade) is detailed on Drawing D-2 -Plan During Construction Phase. Describe other erosion prevention practices (list and describe). Not applicable stormwater Pollution Prevention Plan -Bank Stabilization Project January 2007 ConAgra Food Ingredients Inc. Our File No. 207200 ConAgra Flour Milling Co. -Hastings, MN Page 6 of 10 Stormwater Pollution Prevention Plan (SWPPP) ConAgra Food Ingredients Hastings, MN Sediment Control Practices IV.C Describe sediment control practices used to minimize sediments from entering surface waters, including curb and gutter systems and storm drain inlets. At a minimum, these sediment control practices must include: • Sediment controls for temporary or permanent drainage ditches and sediment basins that are designed as part of a treatment system • Installation of check dams or other grade control practice to ensure sheet flow and prevent rills (for slope lengths greater than 75 feet with a grade of 3:1 or steeper). Please see attached Drawing D-2 -Plan During Construction Phase • Sediment control practices on all down gradient perimeters prior to land disturbing activities. • Storm drain inlet protection for all inlets. Not applicable • Silt fencing or other sediment control surrounding temporary soil stockpiles. Please see attached Drawing D-2 -Plan During Construction Phase • Minimize vehicle tracking of sediments (e.g., stone pads, concrete or steel wash racks, or equivalent systems). Please see attached literature from Brock-White Construction Materials relating to Mud Mats. • Street sweeping of tracked sediment. • Temporary sedimentation basins (see Part III.B). Not applicable Dewaterin and Basin Drainin IV.D Will the ro ect include dewaterin or basin drainin ? v Yes No If yes, describe BMPs used so the discharge does not adversely affect the receiving water or downstream landowners. The concrete block cofferdam at the toe of the retaining wall would have a settling pond located at the downstream end (low point) so any silt collected within the cofferdam would settle and filter the water prior to seeping out into the river. In the event of a heavy rainfall, the following dewatering plan would be implemented: • Insert a trash pump in the settling pond Set-up discharge line vertically to the top of embankment ^ Start trash pump and discharge water into a settling pond area located east of the construction site /south of the rail tracks as outlined on Drawing D-2 -Plan During Construction Phase • This settling area would permit silt to slowly settle and allow filtered water fo be discharged over the rock edge into the river Stormwater Pollution Prevention Plan -Bank Stabilization Project January 2007 ConAgra Food Ingredients Inc. Our File No. 207200 ConAgra Flour Milling Co. -Hastings, MN Page 7 of 10 Storrnwater Pollution Prevention Plan (SWPPP) ConAgra Food Ingredients Hastings, MN Additional BMPs for S ecial Waters and Dischar es to Wetlands A endix A, Parts C and D S ecial Waters. Does our ro ect dischar a to s ecial waters? Yes No If no, ski to Wetlands section below. If proximity to bedrock or road projects where the lack of right of way precludes the installation of any of the permanent stormwater management practices, then other treatment such as grassed swales, smaller ponds, or grit chambers is required prior to discharge to surface waters. Describe what other treatment will be provided. Describe erosion and sediment controls for exposed soil areas with a continuous positive slope to a special waters, and temporary sediment basins for areas that drain 5 or more acres disturbed at one time. Describe the undisturbed buffer zone to be used (not less than 100 linear feet from the special water). Describe how the permanent stormwater management system will ensure that the pre and post project runoff rate and volume from the 1, and 2-year 24-hour precipitation events remains the same. Describe how the permanent stormwater management system will minimize any increase in the temperature of trout stream receiving waters resulting in the 7, and 2-year 24-hour precipitation events. Wetlands. Does your project discharge stormwater with the potential for significant adverse impacts to a wetland (e.g., conversion of a natural wetland to a stormwater and ? Yes No If Yes, describe the wetland mitigation sequence that will be followed in accordance with Part D of Appendix A. Ins ections and Maintenance IV.E Describe procedures to routinely inspect the construction site: • Once every seven (7) days during active construction and, • Within 24 hours after a rainfall event greater than 0.5 inches in 24 hours. Inspections must include stabilized areas, erosion prevention and sediment control BMPs, and infiltration areas. An inspection sheet detailing sediment /erosion control measures (i.e. check dams, drainage swales, silt curtains /fences, mud mats) would be in the construction office and available to all regulatory agencies for viewing. The contractor supervisor or designated person would check off each item on the sheet on a daily basis to ensure these measures are not compromised. Any changes /alterations to the design /maintenance of these control measures would be documented and the SWPPP properly updated. The updated SWPPP would remain on ConAgra's site for a least three years after the NOT (Notice of Termination) Form was submitted. stormwater Pollution Prevention Plan -Bank Stabilization Project January 2007 ConAgra Food Ingredients Inc. Our File No. 207200 ConAgra Flour Milling Co. -Hastings, MN Page 8 of 10 Stormwaler Pollution Preven4ion Plan (SWPPP~ ConAgra Food Ingredients Hastings, MN Pollution Prevention Mana ement Measures IV.F Describe practices to properly manage and dispose of solid waste, including trash (IV.F.1) An area solely designated for concrete wash-out is illustrated on attached Drawing D-2 -Plan During Construction Phase. All trash would be disposed of in designated garbage bins provided by ConArga. Described practices to properly manage hazardous materials (IV.F.2). A lockable container (20') would contain skids c/w containment curbs to properly store gasoline, fuels. A spill kit would also be located in the container. MSDS data sheets would be on site for all materials used on the site. Equipment would be fuelled in the designated area as illustrated on Drawing D-2 -Plan During Construction Phase. This area is located in anon-drainage area. An earth berm c/w liner would surround the fuelling area to prevent any leaks, spills from contaminating the site. Describe practices for external washing of trucks and other construction vehicles (IV.F.3) No vehicles would be permitted to be washed on site throughout the construction period. Describe your spill prevention plan. An emergency contact list would be generated /posted on site in the event of a spill. An emergency spill kit would be located in the container for minor leaks and remediation. Describe measures to address sanitary and septic waste. All employees would use ConAgra's existing washroom facilities. Final Stabilization (IV.G) ~ Describe how you will achieve final stabilization of the site (IV.G). Submit a NOT within 30 days after final stabilization. The only area requiring final stabilization is the area behind the new precast block retaining wall. All sloped granular material (4 horizontal to 1 vertical) would be covered with geotextile fabric c/w a layer ofrip-rap (12"). Upon completion ofrip-rap work and site inspection by applicable agencies, our firm would remove the sediment control measures around the site and submit a NOT form. Stormwater Pollution Prevention Plan -Bank Stabilization Project January 2007 ConAgra Food Ingredients Inc. Our File No. 207200 ConAgra Flour Milling Co. -Hastings, MN Page 9 of 10 S4err~nwa4er Pellu4ien PrQVen4ien Plan (SWPPP) ConAgra Food Ingredients Hastings, MN Retention VIII. your record retention procedures (must be kept at the site) (III.D). Records must • Copy of SWPPP and any changes • Inspection and maintenance records • Permanent operation and maintenance agreements • Calculations for the design of temporary and permanent stormwater management systems. All documents relating to the SWPPP, inspection and maintenance records, any agreements and calculations for temporary and permanent storm water management systems would be located in the construction frailer. Any field changes to the design, records etc. would be documented as soon as possible. The updated information would be available for inspection / review by all interested parties and copy of any updates would be submitted to ConAgra on weekly basis. stormwater Pollution Prevention Plan -Bank Stabilization Project January 2007 ConAgra Food Ingredients Inc. Our File No. 207200 ConAgra Flour Milling Co. -Hastings, MN Page 10 of 10 ~~, I I III ,.~- /// ~~~ ,,s -'. Ili I~ li l ~;, ~.. {' _ ~_.. ~ a_.. ~._. a :~ .- •~ ~~~~~ ~~'~4~3~~ eK Ws~~~~~~~ w~~~~~ ~~ i ~~~ ~ ~~ ~~° 4 3 gg~ r ~ ~~ R~ ~~ a,, a ~~ Y e z z E' ~I a a~ wy co a? x'- ~I~I~ o~~ 0 City Council Minutes September 19, 2005 Approve Stormwater Plan-SUP #2005-23: ConAgra Floodwa^ at 2005 Vermillion Street (SACC Group) Associate Planner Jenson stated that ConAgra has provided a map of the drainage patterns for the entire site, as requested by the City Council. Mayor Werner stated that a Stormwater plan for the entire site was request, which would be a significant document, not just a map. City Administrator Osberg stated that-the Special Use Permit for this project has been approved by the City Council, with a condition that the Stormwater drainage plan be reviewed by staff, which is what is typically done. Public Works Director Montgomery stated that the City is not in a position to require ConAgra to change their flow as a part of this SUP; the water on the site is not proposed to change. The Council discussed increased erosion and impervious surfaces, as well as water runoff concerns. There was additional discussion about meeting with ConAgra regarding water concerns. Moved by Councilmember Hicks to approve the stormwater plan with the condition that staff meet with ConAgra regarding a comprehensive Stormwater management plan for the site. Councilmember Hicks withdrew his motion. Moved by Coucnihnember Hicks, seconded by Councilmember Schultz to table the action until October 3, 2005 Council meeting for ConAgra to prepare Stormwater site map. 7 Ayes; Nays, none.