11KOS972821A Wetland Inspection Plan - 7-3-25.pdf
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- Attached to
- KOS972821A (26-01)
- Solicitation number
- 009-RFB-WRBWL-CY26-01
- Issued by
- Jasper County, Alburnett City, Iowa
About this file
This is a Wetland Inspection Plan document issued by the Iowa Department of Agriculture & Land Stewardship, Division of Soil Conservation and Water Quality, in partnership with Ducks Unlimited, for the Manske Wetland construction project (KOS972821A) in Kossuth County, Iowa. The plan outlines quality control and quality assurance requirements for approximately 17 acres of nutrient reduction wetland development, encompassing selective clearing, excavation, grading, steel sheetpile installation totaling 1,444 square feet, 515 linear feet of tile installation, 91 linear feet of drawdown pipe, 548 tons of riprap placement, and 16 acres of buffer seeding. Construction must commence within 14 days of the preconstruction meeting with substantial completion required by December 31, 2026, and final seeding deadlines of May 15, 2027 for structure seeding and June 30, 2027 for buffer seeding. The inspection plan details full-time or intermittent inspection requirements by a Design Engineer-of-Record or Qualified Technician for critical work items including tile exploration, soil confirmation, core trench excavation and backfill, embankment construction, sheet pile installation, water control structure installation, and grouting operations. As-built survey documentation and comprehensive record drawings must be submitted upon project completion, including all construction changes, final quantities, site layout modifications, dimensional updates, and certified location and elevation data for all major project components.
The inspection plan establishes that the contractor bears responsibility for quality control while the Design Engineer assumes quality assurance oversight, with the contractor required to submit material certifications for all pipe, tile, geotextile, granular material, and riprap for Design Engineer approval. Shop drawings for the sheet pile weir, drawdown structure, outlet pipes, grout mix, and seed mix designs must receive Design Engineer approval prior to placement. The three benchmarks established on-site by the Engineer serve as reference points for construction elevation verification. Sealed bids for the project were due by 3:00 PM Central Daylight Time on May 20, 2026, with an estimated construction cost range of $350,000 to $450,000. Successful bidders are required to furnish a bid bond equal to ten percent of the bid amount and a Performance/Payment Bond equal to 100 percent of the contract price. The sequence of construction will be determined post-award during the preconstruction meeting, with timing dependent on crop harvest schedules.
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Text version
IA-340-15 (KOS972821A) PAGE 1 OF 3 JULY 3, 2025
IA-340-15 - Manske Wetland Inspection Plan (Kos972821A)
The sequence of construction will be determined with the contractor after the contract is awarded, the start date planned, and whether crops have been harvested. This will be discussed at the pre-construction meeting. The easement boundary stakes will be placed by a third party PLS retained by DU. Three (3) benchmarks to be used for construction have already been placed on-site by the Engineer.
Quality Control (QC) is the responsibility of the contractor, but any work deemed to not be in accordance with the plans and specifications based on inspections completed shall be reworked.
Quality Assurance (QA) is the responsibility of the Design Engineer-of-Record. The Contractor is responsible to provide materials that meet or exceed the requirements provided on the plans and specification. The Design Engineer will review material certifications provided for all pipe/tile, geotextile, granular material, and riprap. Shop drawings shall also be submitted for approval for the sheet pile weir, drawdown structure, and outlet pipes. The grout mix and seed mix designs shall also be submitted and approved by the Design Engineer prior to placement.
Below is a list of anticipated tasks to be completed along with the amount of inspections required and the experience level of the inspector needed. Engineer refers to either the Design Engineer-of- Record or an Engineer designated by such. Qualified Technician refers to an individual with sufficient technical background and experience to properly assess the individual work items described below that will be completed by the Contractor.
• Tile Exploration – Full time by Engineer or Qualified Technician The site has several tiles on site based on maps provided by the landowner and from our tile investigation. A tile investigation was completed during design to determine the location and depth of tiles shown on the plans. The Contractor shall complete the exploration to confirm the depth and location in the presence of the Engineer or Technician with survey equipment. This information will be used by design engineer to adjust the tile outlets as needed to provide suitable outlet(s) based on this acquired information.
• Soil Confirmation – Full time by Engineer or Qualified Technician The Contractor shall excavate test pits as needed to confirm suitable soils are available before beginning stripping operations.
• Site stripping - No observation required.
Site stripping can occur without any site inspection being required. The contractor will need to implement storm water and sedimentation control measures.
• Core Trench Excavation and Backfill – Full time by Engineer or Qualified Technician The core trench can occur after stripping of the dike area is completed. Any tile found shall be removed within the 15 feet beyond the outside footprint of the dike. Suitable cohesive
IA-340-15 (KOS972821A) PAGE 2 OF 3 JULY 3, 2025
borrow material shall be placed and compacted in the core trench using Method 2 as directed in IA-23 and shall be inspected to verify use of specified equipment and the maximum lift thickness are not exceeded. Dewatering shall be completed as needed to assure proper moisture content of backfill materials are not exceeded.
• Embankment Construction – Intermittent to Full Time by Engineer or Qualified Technician The dike shall be constructed to the design height consisting of suitable cohesive material.
This critical item of work shall be inspected to assure proper material, moisture, and placement method. Full-time inspection shall be implemented if the problems arise, or the rate of placement necessitates this level. If work is progressing well and the rate of placement allows, this work shall be inspected intermittently, but at regular intervals. The location and elevations of the dike shall be checked by Engineer or Qualified Technician with survey equipment when Contractor is nearing final construction grade and before topsoil placement. As-built survey shall be completed after topsoil placement has been completed.
• General Grading - Intermittent by Engineer or Qualified Technician The site includes grading of the wetland, sediment forebays, and submerged berms. In addition, the borrow area is identified on the plans. The Engineer or Qualified Technician will verify the location and dimensions of the sediment forebays and submerged berms using survey equipment. The borrow area shall also be checked to make sure final grading allows for drainage and has adequate topsoil placement.
• Sheet Pile Installation - Full time by Engineer or Qualified Technician The sheet pile installation shall be inspected by a technician familiar with this type of work or the design engineer. The initial sheets shall be verified for straightness and location. The final dimensions, including length and elevation, shall be checked prior to installation of the pile cap, and trimming the tops of the sheets.
• Water Control Structure Installation - Full time and Intermittent by Engineer or Qualified Technician The location and elevation of the installation of the water control structure, inlet riser, and outlet pipes shall be verified by technician or surveyor prior to backfilling. The Engineer or Qualified Technician shall be on site full-time during the installation of the sand diaphragm.
• Downstream Basin and Channeling - Intermittent by Engineer or Qualified Technician The downstream stilling basin and outlet channel shall be checked for location, dimensions, and elevations prior to placement of the geotextile fabric and riprap. Prior to grouting, the Engineer or Qualified Technician shall ensure that the geotextile fabric is in place beneath the riprap and the verify the thickness of the riprap.
IA-340-15 (KOS972821A) PAGE 3 OF 3 JULY 3, 2025
• Grouting - Full time by Engineer or Qualified Technician Grout is to be placed into the voids of the riprap. The thickness and cleanliness of the riprap shall be checked prior to grouting and adequate coverage shall be checked during grout placement.
• Tile Intercepts and Outlets - Intermittent by Engineer or Qualified Technician The Engineer or Qualified Technician shall verify the tile intersection location and elevation. Once established, the tile shall be placed to the designated outlet location by Contractor. The Engineer or Qualified Technician shall observe all joint connections prior to backfilling and shall measure the intercepts and outlet with surveying equipment. The Engineer or Qualified Technician shall also verify that adequate soil cover has been obtained, and any riprap or erosion stone is properly placed at the outlet.
• Seeding - Intermittent by Engineer or Qualified Technician Seed bed preparation shall be checked prior to seeding, along with the thickness of the topsoil over fill and borrow areas. Seed tags shall be verified.
The record as-built drawings shall include the following information:
• All construction changes and clarifications shall be shown in red.
• Updates to final quantities.
• Site layout changes (structure centerline and slope changes).
• Dimension changes.
• Altered lines and grades.
• Final location of appurtenances.
• Project Completion date on Cover Sheet.
• Total Project Cost.
• Quality Assurance Inspector.
• Contractor/Firm providing Quality Control.
• Each sheet labeled As-Built with certification on Cover Sheet and EOR initials on each sheet.
• Location and elevation along top of sheet pile weir.
• Location and elevation of stilling basing and outlet channel.
• Location and elevation of tile intercepts and outlets, along with pipe sizes.
• Location and elevation of sedimentation basin.
• Location and elevation of top of drawdown structure and inlet structure.
• Cross section(s) near the center of the wetland to verify elevations.
• Location and elevation of top and toes of the embankment, including the wave berm.
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