ENGINEER S REPORT MAIN TILE IMPROVEMENTS DRAINAGE DISTRICT NO. 131 WRIGHT COUNTY

Transcription

1 ENGINEER S REPORT MAIN TILE IMPROVEMENTS DRAINAGE DISTRICT NO. 131 WRIGHT COUNTY 2013

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3 TABLE OF CONTENTS Page I. Introduction 1 II. Background 1 III. Existing Conditions 1-4 IV. Improvement Options 4-6 V. Recommendation 6-7 VI. Reclassification 8 VII. Wetlands 8 VIII. Administration 8 APPENDIX Cost Estimate Plat N:\Projects\WRC \Cler\Design\DD 131 Report.doc 12/24/2013/10:28 AM

4 I. Introduction The following report on the investigation for improvements for Drainage District No. 131 is herein submitted. A petition was filed to investigate the main tile of DD No. 131 due to a lack of drainage that results in prolonged flooding at the north end of the district. There was also some concern related to the surface drainage of land within the district. It was requested that the natural surface drainage be looked at along the north line of Section 27 and adjacent to county road C54. It was also requested that a private tile line at the upper end of the main tile be investigated to determine if it is draining land outside of the district boundary. II. Background DD No. 131 was established April 18, 1916 and construction was completed October 30, 1917 for $26, The district consists of a main tile with four laterals and drains 2,120 acres. The main tile is located five miles east of Eagle Grove and runs through Sections 27, 34 and 35 of Dayton Township and Sections 2, 11 and 12 of Woolstock Township. The main tile outlets into the White Fox Creek. There is no record of significant repairs being made in the district. III. Existing Conditions Main Tile Drainage The main tile of DD No. 131 consists of 22,000 feet of clay tile and ranges in size from 10 to 32 inches. A capacity analysis was done on the main tile using the grades and pipe sizes shown on the original profile and as measured in the field. The tables below show the tile size, grade, capacity, drainage area, and drainage coefficient of the existing tile. The drainage coefficient is the amount of water a tile can drain per acre within a 24 hour period. A typical modern design would be for a ½ drainage coefficient. The majority of the main tile has a drainage coefficient of 1/8 with the exception of a 6,450 foot stretch of tile that has a 3/32 drainage coefficient. Land owners noted that water tends to drain slowly from the upper reaches of the tile. This is likely due to lack of capacity in relation to the amount of private tile draining into the system. Looking at aerial photos, it appears that almost half of the land within the district is drained by private tile lines. A letter written by the Board in 1970 noted that the district tile system was overloaded at that time. The four lateral tiles are Lateral 1, A, B and 2. Lateral 1 and 2 tie directly into the main tile and have drainage coefficients greater than the main tile. Lateral 1 has a drainage coefficient of ¼ and Lateral 2 has a drainage coefficient of 3/8. Lateral A and B tie into Lateral 1. Lateral A has a drainage coefficient of 1/8 and Lateral B has a coefficient of 1. N:\Projects\WRC \Cler\Design\DD 131 Report.doc 12/24/2013/10:28 AM 1

5 Main Tile Capacity Analysis Table DD 131 Station Existing Tile (in.) Existing Grade Existing Capacity (cfs) D.A. (Acres) Existing D.C % /8" % /8" % /8" % /8" % /8" % /8" % /32" % /32" % /32" % /32" % /32" % /8" % /8" % /32" Lateral Tile Capacity Analysis Table Station Existing Tile (in.) Existing Grade Existing Capacity (cfs) D.A. (Acres) Existing D.C. Lat % /4" % /8" % /8" Lat A % /8" Lat B % " Lat % /8" N:\Projects\WRC \Cler\Design\DD 131 Report.doc 12/24/2013/10:28 AM 2

6 Surface Drainage Two areas were requested to be looked at with concerns on how the surface water drains through the district. Surface Drainage Area 1: The first area is at the north fence line of Section 27 as shown on the attached map. Approximately 24 acres drain from the north into Section 27. The surface water from the north drains through a 24 inch road culvert and ponds in the road ditch until it drains into a tile intake or reaches a depth that allows it to surface drain into the field to the south. The intakes in the ditch and the main tile are not sufficient to drain a moderate rainfall since the tile system is not designed to act as a storm sewer. Once the water gets deep enough it flows into the field to the south and floods the field. The concern the west property owner (NE NW) has is that the south ditch bank has been artificially built up on the east side (NW NE) of the fence causing water to flow across his field when it should naturally drain to the east. Survey shots taken in the field and on the top of slope of the road ditch show that the water should naturally drain into the east field. The top of slope elevation on the east side is 0.77ft lower than the west side at their respective low points. The reason water may flow into the west field first is because the water must pass under a field entrance to get to the east field. The culvert under the gravel road is a 24 inch but the culvert under the field entrance is only a 15 inch. This likely caused water to pass under the road at a higher rate than it can pass under the field entrance causing the water to back up on the west side. All things being equal, a 24 inch pipe has 2.7 times the capacity of a 15 inch pipe. If the field entrance culvert is plugged or the openings are obstructed then this would compound the problem. Increasing the field entrance culvert size could help equalize the flow of water on both sides of the field entrance. This is not a drainage district issue. The land owners should work with the Secondary Roads Department if they wish to increase the field entrance culvert size. Increasing the tile size will help drain the fields that flood quicker. Surface Drainage Area 2: The second area with surface drainage issues is north and south of county road C54 in Sections 27 and 34 as shown on the attached map. The land in Section 27 drains south into Section 34 through a 60 x70 corrugated metal arch pipe. There is a natural waterway through the north field that drains approximately 518 acres. The north field has a history of flooding and the land owner has attempted reshaping the waterway to bring the ground elevation up. Their concern is that the land to the south is at a higher elevation than their low ground causing the area to flood with the only outlet being the tile intake in the road ditch. Survey ground shots show that the north field is 0.5ft lower than the highest field elevation to the south. At a minimum this causes the north field to flood 0.5ft with the only outlet being the ditch intake to the district tile. Two options are available to relieve the flooding in the field. One is to grade the south field to allow water to flow freely and the other option is to improve the drain tile to drain the north field quicker when it floods. A properly designed grassed waterway would be designed to convey the peak runoff from the 10 year, 24 hour duration storm. The field to the south however does not provide adequate grade or depth to install a waterway that would transmit this flow. At best there could be a very shallow channel cut that would allow the north field to drain over a period of time. A typical grassed waterway would ideally have a minimum N:\Projects\WRC \Cler\Design\DD 131 Report.doc 12/24/2013/10:28 AM 3

7 grade of 1% but the maximum grade possible through the south field is 0.08% which would tend to silt in. Drainage districts typically do not control how surface water flows through a field and to do so would be to create a district controlled ditch or waterway. This would also be an expense paid for by the entire district that would benefit only one or two land owners. To help alleviate the flooding in this area it is recommended to improve the tile capacity or the land owners could work together to grade the field. Drain tile do not function as a storm sewer and the field will still flood after heavy rain storms. However, an improved drain tile would drain the field faster reducing the amount of crop loss. Private Tile across District Boundary Line It was requested that we investigate the possibility that there is a private tile line draining land from outside the district boundary. The tile in question is at the north end of the district in Section 22 as shown on the attached map. In 1970 the Board was informed that a private tile was installed in the north road ditch running east and west along 260 th Street that drained land from outside of the district watershed boundary to the west. The land owner was directed to disconnect the tile line 420 feet west of the southeast corner of the SW ¼ of Section 22. If the tile was not disconnected then it would be done by the county. There is no record if this tile line was disconnected. We probed across the road ditch in a couple of locations and were not able to find the private tile line. It is possible that the tile no longer exists or we missed it with our probe. To determine if the tile line is still in existence and to see if it drains beyond the district boundary the district could have a contractor trench across the road ditch near the district boundary location. If the tile is found to be intact the district could either disconnect the line to the west or allow the land owner to annex into the district. If a project is selected then it would be recommended to include the exploration as part of the project. IV. Improvement Options Improvement options for the ¼ and ½ drainage coefficient are shown below. In order to improve the drainage at the north and south ends of Section 27 and to improve the drainage capacity in general for the entire district, it will be necessary to increase the main tile size. The options include completely replacing the existing main or installing a parallel relief tile line. Costs are provided to compare the presented options. Another option would be to televise the existing main to determine if the existing tile has obstructions or broken segments that are impeding the tile flow. This would confirm if the existing tile is suitable as a relief tile or if the tile is not operating at its peak capacity. There may be improvement by simply repairing any damaged sections. Aerial photos appear to show that nearly half of the district is drained by private tile. These tile systems can only operate effectively if they have an adequate outlet. As mentioned above, the existing tile system has a 1/8 drainage coefficient. Increasing the capacity to the ¼ or ½ drainage coefficient would double or quadruple the capacity respectively. Option 1 Televise Existing Main Tile This option would be to televise the existing main for two reasons. First it would identify any existing damaged or obstructed sections of tile that may be obstructing the flow. Examples would include collapsed pipe sections, sedimentation, or private tile inlets that extend too far into the pipe. If an improvement option is not selected then this would at least confirm that the N:\Projects\WRC \Cler\Design\DD 131 Report.doc 12/24/2013/10:28 AM 4

8 existing tile is operating at its peak efficiency. The second reason to televise would be to gauge the suitability of the tile to remain in service if a relief tile is installed. A relief tile will rely on the existing main for a large portion of the drainage capacity and it would be beneficial to know if the combined tile system will operate as expected. As part of this option the private tile line would be investigated at the north end of the district to determine if land outside of the district is being drained. The estimated cost for this option is $51,503 as shown on the cost estimate in the Appendix. The cost would include exposing the existing main periodically, repairing the exposed sections, televising the main, surveying the tile location and depth, and reviewing the televising report. It is possible to scale the extent of the televising down if there are specific areas that landowners feel would need to be investigated. Costs to make repairs would be determined after the tile is televised. An estimated range to repair an isolated section would be $500 - $1,500 per repair. Option 2A/2B Increase Tile Capacity to ¼ D.C. This option would increase the tile capacity from a 1/8 drainage coefficient to a ¼ drainage coefficient, doubling the capacity of the main. There are two ways to accomplish this. One is to install a relief tile line and the second is to replace the existing main with a larger tile line. Option 2A would install a relief tile line parallel to the existing main. The relief tile would follow the grade of the existing tile and range in size from 30 inches at the outlet to 12 inches at the upper end. Periodic cross connections would be made between the new and old tile to help equalize the flow. This option relies on a nearly 100 year old tile that will require maintenance as it ages. The estimated cost for this option is $962,320 as shown on the cost estimate in the Appendix. Option 2B would remove and replace the existing main with a larger pipe that would follow the existing main grade and alignment. The new main would range in size from 42 inches at the outlet to 12 inches at the upper end. The lower 2,400 feet of the existing tile, near the outlet at the White Fox Creek, has limited cover and increasing the tile size would reduce this further. It may be necessary to shift the alignment of the new tile into deeper cover in order to maintain a minimum level of cover. Ideally a minimum of 2ft of cover would be maintained over the tile however it is possible there would be limited stretches with only a foot of cover. The land along the White Fox is not currently cultivated which eases the need for more cover. The estimated cost for this option is $1,221,449 as shown on the cost estimate in the Appendix. Option 3A/3B Increase Tile Capacity to ½ D.C. This option would increase the tile capacity from a 1/8 drainage coefficient to a ½ drainage coefficient, nearly quadrupling the capacity of the main for most of its length. As with Option 2, there are two ways to accomplish this. One is to install a relief tile line and the second is to replace the existing main with a larger tile line. Option 3A would install a relief tile line parallel to the existing main. The relief tile would follow the grade of the existing tile and range in size from 48 inches at the outlet to 12 inches at the upper end. Periodic cross connections would be made between the new and old tile to help equalize the flow. As with Option 2B, the increased tile size reduces the amount of cover along N:\Projects\WRC \Cler\Design\DD 131 Report.doc 12/24/2013/10:28 AM 5

9 the lower 2,400 feet. It would most likely be necessary to shift the alignment of the tile to provide more cover. Alternatively to shifting the alignment, arched pipe could be utilized to attain the maximum amount of cover. This option relies on a nearly 100 year old tile that will require maintenance as it ages. The estimated cost for this option is $1,339,950 as shown on the cost estimate in the Appendix. Option 3B would remove and replace the existing main with a larger pipe that would follow the existing main grade and alignment. The new main would need to range in size from 54 inches at the outlet to 12 inches at the upper end. However, due to the lack of cover at the outlet, the 54 inch pipe would not have sufficient cover and would likely have no cover in depressed areas. The original drainage plan called for a drainage ditch for the first 1,000 feet at the outlet but this was changed to tile before construction. In lieu of a 54 inch tile, an open ditch could be installed for the last 1,000+ feet of the outlet. This will require the purchase of right of way for the ditch and the construction of a headwall at the tile outlet. It will also be necessary to work with the Army Corps of Engineers to obtain any required permits to construct an open ditch within the flood plain of the White Fox Creek. The alignment of the tile may need to be shifted into higher ground to provide a minimum level of cover. Ideally a minimum of 2ft of cover would be maintained over the tile however it is possible there would be limited stretches with only a foot of cover. The estimated cost for this option is $1,587,005 as shown on the cost estimate in the Appendix. The advantage of the replacement options is that the entire length of main tile will be new and not rely on the old existing tile line. Each of the improvement options is expensive with a high average cost per acre. The high average cost is due to the shape of the district. It is long but also narrow which results in high construction costs but relatively fewer acres paying towards the construction. A summary of costs is below. Cost Summary of Options Option Description Estimate Avg. $/AC Avg. $/AC over 10yrs. 1 Televise Main Tile $51,503 $24 $3 2A Main Relief Tile 1/4" Drainage Coefficient $962,320 $454 $62 2B Main Replacement tile 1/4" Drainage Coefficient $1,221,449 $576 $78 3A Main Relief Tile 1/2" Drainage Coefficient $1,339,950 $632 $86 3B Main Replacement Tile 1/2" Drainage Coefficient $1,587,005 $749 $102 V. Recommendation There is a desire from some land owners to improve the drainage through the main tile system and to alleviate some surface drainage problems. With intense row-cropping the need for good drainage is vitally important, and to compound the issue, the added pattern tiling over the years has more than ever created a greater need for more subsurface drainage capacity. Subsurface drainage systems are only as efficient as their outlet. An article provided by the Iowa State University Extension is quoted below regarding the benefits of improved drainage. 6 N:\Projects\WRC \Cler\Design\DD 131 Report.doc 12/24/2013/10:28 AM

10 Investment Analysis The major reason for installing subsurface drainage is to improve the productivity of the farmland. Higher yields translate into more returns. This is especially true in recent years due to higher grain prices. So the investment decision is based on whether the higher crop returns will justify the investment in subsurface drainage. A secondary benefit is that fields will dry out quicker, allowing planting and harvesting to be completed earlier in the spring and fall. It also provides a larger window of time for a farmer to plant and harvest the crop allowing it to be done in a more efficient manner in terms of time and money. This is especially advantageous for farmers who have large acreages to cover. Specific advantages of tile drainage are: 1. More consistent yields Allows for more efficient use of resources Reduces financial risk 2. Earlier and more timely planting 3. Improved harvesting conditions 4. Less wear and tear on equipment 5. Less power required for field operations 6. Better plant stand 7. Less plant stress 8. Fewer plant diseases 9. Less soil compaction Another major advantage of tile drainage is the increase in sale value of the land. If the land will be sold in the future, the advantages listed above will be capitalized into the value of the land. Subsurface drainage is a long-term investment. The investment is made up-front but the benefits are spread over many future years. So the investment decision should be made with the time-lag in mind. The most difficult part of computing a tile investment analysis is estimating the yield response from the improved drainage. The size of the expected yield improvement dramatically impacts the economic feasibility of installing tile drainage as shown in the example below. The improvement options would increase the capacity of the main providing a better outlet for the laterals and private tile lines. Each of the laterals would see a benefit to the increased capacity of the main by either more closely matching the laterals drainage coefficients or by freeing up bottlenecks in the system. The option to televise and make repairs would serve to ensure the existing system is operating at its peak capacity. The options are presented for the landowners in the Drainage District to discuss and determine if any of the improvement options appear to be worthy of pursuing. Although an improvement project would increase the capacity of the main tile, there would still be periods with standing water in the field. Drain tile are designed to drain the subsurface moisture. They are not designed to act as storm sewers to drain surface water quickly. Increasing the tile size would decrease the amount of time it takes to drain the excess moisture. A field s drainage will also depend on the amount of private tile installed. N:\Projects\WRC \Cler\Design\DD 131 Report.doc 12/24/2013/10:28 AM 7

11 VI. Reclassification The original classification is in use to apportion costs and does not have a separate schedule for each lateral. If an improvement option is chosen then a reclassification would be required for DD 131 (Section ). A reclassification is estimated to cost $20,000. VII. Wetlands Improvement projects have the potential to affect wetlands and farmed-wetlands. It is up to the individual landowner to notify the Board of Supervisors if the project will disturb any wetlands that could result in the need for mitigation to avoid jeopardizing any producers FSA program eligibility. Landowners need to present this information at or before the public hearing. If wetlands or farmed-wetlands exist, it will be necessary to mitigate them if an improvement project is selected. The mitigation needs to be done before construction starts so prompt action from the landowners is important. The drainage district may elect to pay for the mitigation costs. VIII. Administration The Code of Iowa requires a public hearing date be set regarding this report and notice given to all district landowners (Section , para. 1.c.). If a project is approved, a public bid letting will also be required (Section ). N:\Projects\WRC \Cler\Design\DD 131 Report.doc 12/24/2013/10:28 AM 8

12 N:\Projects\WRC \Cler\Design\DD 131 Report.doc 12/24/2013/10:28 AM APPENDIX

13 Opinion of Probable Costs Main Tile Improvements DD No. 131 Wright County Dec-13 Option 1 - Televise Main Tile (22,000 ft) item description quantity unit unit cost extension 1. Mobilization 1 ls $1,500 $1, Televise 6" to 10" 1,500 lf $0.70 $1, Televise 12" to 18" 6,000 lf $0.85 $5, Televise 24" to 30" 12,100 lf $1.20 $14, Televise over 30" 2,400 lf $1.40 $3, Expose Existing Tile 14 ea $500 $7, Repair Exposed Tile 14 ea $200 $2, Tile Exploration 16 hr $150 $2,400 Total $37,730 10% Contingency $3,773 Bidding Phase & Contracts $2,500 Engineer Review Televising Report $5,000 Survey Tile Location $2,500 Estimated Total Project $51,503 Average Assessment DD 131: $51,503 /2,120 ac= $24.29 Average Cost Per Acre Over 10 6%: $3.30 per acre per year N:\Projects\WRC \Cler\Design\ Costs

14 Opinion of Probable Costs Main Tile Improvements DD No. 131 Wright County Dec-13 Option 2A - DD 131 Relief Tile 1/4" Drainage Coeficient (22,000 ft) item description quantity unit unit cost extension 1. 12" RCP 1,500 lf $20 $30, " RCP 1,500 lf $22 $33, " RCP 1,500 lf $24 $36, " RCP 1,500 lf $26 $39, " RCP 3,500 lf $28 $98, " RCP 10,000 lf $32 $320, " RCP 2,500 lf $36 $90, " CMP Tile Outlet 20 lf $30 $ Tile Intake 2 ea $500 $1, Flow Equalization Lines 10 ea $500 $5, Field Tile Connections 110 ea $200 $22, Locate Existing Tile 24 hr $150 $3, Trench Stabilization Rock 1,100 tn $25 $27, Lateral Connection 2 ea $600 $1, Seeding, Fertilizing, Mulch 6 ac $1,500 $9,300 Total Construction $716,200 10% Contingency $71,620 Survey, Records Review, Report & Hearings $10,000 Survey, Plans, Specifications, Bidding Phase & Contract Documents $9,000 Construction Staking, Construction Review & Administration $35,000 Legal Notices, Miscellaneous $1,500 ROW Damages $2,250/ac) $99,000 Reclassification $20,000 Estimated Total Project $962,320 N:\Projects\WRC \Cler\Design\ Costs

15 Average Assessment DD 131: $962,320 /2,120 ac= $ Average Cost Per Acre Over 10 6%: $61.67 per acre per year Secondary Roads Expense 260th Street Crossing $5,400 C-54 Crossing (Bored) $27,000 Keokuk Avenue Crossing $5, th Street Crossing $6,100 Lee Avenue Crossing $6,500 C-60 Crossing $6,500 Total $57,400 N:\Projects\WRC \Cler\Design\ Costs

16 Opinion of Probable Costs Main Tile Improvements DD No. 131 Wright County Dec-13 Option 2B - DD 131 Replacement Tile 1/4" Drainage Coeficient (22,000 ft) item description quantity unit unit cost extension 1. 12" RCP 500 lf $20 $10, " RCP 1,000 lf $22 $22, " RCP 1,000 lf $24 $24, " RCP 1,700 lf $26 $44, " RCP 1,800 lf $28 $50, " RCP 1,200 lf $32 $38, " RCP 2,600 lf $36 $93, " RCP 3,700 lf $40 $148, " RCP 5,000 lf $45 $225, " RCP 3,476 lf $52 $180, " RCP Tile Outlet 24 lf $55 $1, Tile Intake 2 ea $500 $1, Crush and Bury Existing Tile 22,000 lf $2.25 $49, Field Tile Connections 110 ea $200 $22, Locate Existing Tile 24 hr $150 $3, Trench Stabilization Rock 1,100 tn $25 $27, Lateral Connection 2 ea $600 $1, Seeding, Fertilizing, Mulch 6 ac $1,500 $9,300 Total Construction $951,772 10% Contingency $95,177 Survey, Records Review, Report & Hearings $10,000 Survey, Plans, Specifications, Bidding Phase & Contract Documents $9,000 Construction Staking, Construction Review & Administration $35,000 Legal Notices, Miscellaneous $1,500 N:\Projects\WRC \Cler\Design\ Costs

17 ROW Damages $2,250/ac) $99,000 Reclassification $20,000 Estimated Total Project $1,221,449 Average Assessment DD 131: $1,221,449 /2,120 ac= $ Average Cost Per Acre Over 10 6%: $78.28 per acre per year Secondary Roads Expense 260th Street Crossing $5,700 C-54 Crossing (Bored) $38,000 Keokuk Avenue Crossing $6, th Street Crossing $7,000 Lee Avenue Crossing $7,450 C-60 Crossing $7,450 Total $72,400 N:\Projects\WRC \Cler\Design\ Costs

18 Opinion of Probable Costs Main Tile Improvements DD No. 131 Wright County Dec-13 Option 3A - DD 131 Relief Tile 1/2" Drainage Coeficient (22,000 ft) item description quantity unit unit cost extension 1. 12" RCP 500 lf $20 $10, " RCP 500 lf $22 $11, " RCP 500 lf $24 $12, " RCP 1,000 lf $26 $26, " RCP 1,700 lf $28 $47, " RCP 600 lf $32 $19, " RCP 1,400 lf $36 $50, " RCP 1,100 lf $40 $44, " RCP 2,700 lf $45 $121, " RCP 9,300 lf $52 $483, " RCP 2,700 lf $60 $162, " RCP Tile Outlet 20 lf $30 $ Tile Intake 2 ea $500 $1, Flow Equalization Lines 10 ea $700 $7, Field Tile Connections 110 ea $200 $22, Locate Existing Tile 24 hr $150 $3, Trench Stabilization Rock 1,100 tn $25 $27, Lateral Connection 2 ea $600 $1, Seeding, Fertilizing, Mulch 6 ac $1,500 $9,300 Total Construction $1,059,500 10% Contingency $105,950 Survey, Records Review, Report & Hearings $10,000 Survey, Plans, Specifications, Bidding Phase & Contract Documents $9,000 N:\Projects\WRC \Cler\Design\ Costs

19 Construction Staking, Construction Review & Administration $35,000 Legal Notices, Miscellaneous $1,500 ROW Damages $2,250/ac) $99,000 Reclassification $20,000 Estimated Total Project $1,339,950 Average Assessment DD 131: $1,339,950 /2,120 ac= $ Average Cost Per Acre Over 10 6%: $85.88 per acre per year Secondary Roads Expense 260th Street Crossing $5,900 C-54 Crossing (Bored) $38,000 Keokuk Avenue Crossing $7, th Street Crossing $7,450 Lee Avenue Crossing $8,000 C-60 Crossing $8,000 Total $74,350 N:\Projects\WRC \Cler\Design\ Costs

20 Opinion of Probable Costs Main Tile Improvements DD No. 131 Wright County Dec-13 Option 3B - DD 131 Replacement Tile 1/2" Drainage Coeficient (22,000 ft) item description quantity unit unit cost extension 1. 12" RCP 500 lf $20 $10, " RCP 500 lf $22 $11, " RCP 1,000 lf $24 $24, " RCP 500 lf $26 $13, " RCP 1,000 lf $28 $28, " RCP 1,000 lf $32 $32, " RCP 1,500 lf $36 $54, " RCP 1,000 lf $40 $40, " RCP 1,000 lf $45 $45, " RCP 5,000 lf $52 $260, " RCP 6,800 lf $60 $408, " RCP 2,000 lf $100 $200, Open Ditch Excavation (700 LF) 2,000 cy $4 $8, Headwall 1 ea $22,000 $22, Tile Intake 2 ea $500 $1, Crush and Bury Existing Tile 22,000 lf $2.25 $49, Field Tile Connections 110 ea $200 $22, Locate Existing Tile 24 hr $150 $3, Trench Stabilization Rock 1,100 tn $25 $27, Lateral Connection 2 ea $600 $1, Seeding, Fertilizing, Mulch 6.5 ac $1,500 $9,750 N:\Projects\WRC \Cler\Design\ Costs

21 Total Construction $1,269,550 10% Contingency $126,955 Survey, Records Review, Report & Hearings $10,000 Survey, Plans, Specifications, Bidding Phase & Contract Documents $11,000 Construction Staking, Construction Review & Administration $35,000 Legal Notices, Miscellaneous $1,500 ROW Damages $2,250/ac) $99,000 Open Ditch ROW $7,000/ac) $14,000 Reclassification $20,000 Estimated Total Project $1,587,005 Average Assessment DD 131: $1,587,005 /2,120 ac= $ Average Cost Per Acre Over 10 6%: $ per acre per year Secondary Roads Expense 260th Street Crossing $5,400 C-54 Crossing (Bored) $45,000 Keokuk Avenue Crossing $7, th Street Crossing $8,000 Lee Avenue Crossing $10,600 C-60 Crossing $10,600 Total $87,050 N:\Projects\WRC \Cler\Design\ Costs

22 POSSIBLE PRIVATE TILE OUTSIDE DISTRICT BOUNDARY STA: END TILE IMPROVEMENTS AREA 1 SURFACE DRAINAGE CONCERN DISTRICT BOUNDARY MAIN TILE T LA 2 AREA 2 SURFACE DRAINAGE CONCERN EAGLE GROVE 5 Mi. STA: STA: LAT A STA: LAT B MAIN T ILE LAT 1 STA: 0+00 BEGIN TILE IMPROVEMENTS WHITE FOX CREEK STA: 20+00