WAWASEE AREA CONSERVANCY FOUNDATION Thorpe Property Sediment Control Project

As-Built Summary Report

I. INTRODUCTION Cardno JFNew was contracted by the Wawasee Area Conservancy Foundation (WACF) in July 2012 regarding a recently purchased 4.51 acre parcel in Section 27, Township 34 North, Range 7 East, Kosciusko County, Indiana (Appendix A, Sheet 1). The parcel is known as the Thorpe property with access from County Road 1000 North, approximately midway between State Road 13 and County Road 800 East. WACF purchased the parcel to develop a Best Management Practice for reducing sediment and controlling stormwater in the Martin drainage. The entire Martin Drain Watershed is approximately 240 acres, while the drainage area that includes the Thorpe property and above is approximately 120 acres. Approximately 80 acres of the drainage above the Thorpe parcel is row crop agriculture. The intermittently flowing Martin Drain empties into a manmade channel off Lake Wawasee in Vawter Park Subdivision. That lake channel receives sediment laden water from Martin Drain following any rainfall that generates a discharge. While there is no defined stream channel above or within the Thorpe parcel, there is an 18-inch diameter clay tile entering the property from the southwest and discharging onto the neighboring property along the north property line. This tile line followed the lowest elevations of the property and the resulting discharge was at a wetland that is in part on WACF property. The wetland is primarily silver maples; however, the portion on the Thorpe parcel is primarily reed canary grass and had been significantly impacted from past erosion of the adjacent slope. A high ridge that was previously cultivated makes up the majority of the parcel. This ridge was dominated by annuals, primarily foxtail, and is bordered to the east by wooded residential lots and on the south and west by a wooded fence row and a large agricultural field. The agricultural field is under a conservation tillage program; however, the field is still occasionally tilled allowing surface erosion of sediment. Cardno JFNew delineated the wetland on August 22, 2012 and produced a wetland delineation report dated September 28, 2012 to submit to the US Army Corps of Engineers for verification of the wetland boundaries. Approximately 0.64 acres of the 4.51 acre parcel qualified as wetland, considered jurisdictional waters of the United States. The wetland includes most of the northern 80 feet of the property (Appendix A, Sheet 2).

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Thorpe Property Sediment Control Project December 30, 2014 WACF Kosciusko County, IN

II. Project Goals and Construction Planning

The project goal was to retain as much stormwater as possible while trapping sediment to prevent it from moving downstream to Lake Wawasee. Options considered ranged from creating a four acre detention basin to creating a grassed swale and improving the vegetation density and diversity throughout the parcel. The topography within the Thorpe parcel did not allow for a dam like structure typically used to construct detention in a drainage way. Creating a four acre detention basin would have involved moving over 50,000 cubic yards of earth to an off-site location costing in excess of $400,000. A four acre sediment basin was not deemed feasible due to cost. Developing a grassed swale to guide surface water through permanent vegetation on the way through the Thorpe parcel, along with reforestation of the remainder of the parcel was feasible and estimated to cost approximately $32,000. However, a grassed swale and reforestation did not address storage and detention of water, and the concept was not pursued. A concept plan was created using a combination of the above options (Appendix B). The concept called for an approximate ½ acre, dry bottom detention basin in the southwestern corner with a Agri-drain controlled outlet structure leading to a 500 foot long grassed swale along the southern boundary of the wetland edge. This concept plan was used to obtain initial grant funding and seek construction bids. Bidding became problematic as topographic survey and project details were lacking. Following this initial attempt at bidding, WACF contracted Cardno JFNew to develop engineering plans and oversee the bidding and construction of the project. Cardno-JFNew subcontracted with Territorial Engineering, Inc. to complete a topographic survey of the entire project site and develop a base drawing for the engineering plans. The elevation difference from the top of the hill near the center of the parcel to the tile outlet was 14 feet. There are two drainages through the property from the watershed to the south and west. The main drainage lies in the southwesterly corner and was a broad swale that carried approximately 70 percent of the surface drainage (85 acres) from the watershed. The remaining 30 percent of the watershed, approximately 35 acres, passed through a second narrower swale in the eastern half of the parcel. The grade continued to decrease further north and to the east of the property.

A combination sediment basin and grassed swale was subsequently developed as a compromise project (Appendix A, Sheet 3). The plans included a ¾ acre, six foot deep, permanent pool, sediment basin. The outlet of the basin was designed as a rock spillway for minimal maintenance. Beyond the outlet of the basin it was determined that enhancing the wetland was the best option to filter any remaining sediment. The plans called for removing the reed canary grass dominated sod in the defined wetland and then seeding with a more diverse mix of emergent wetland species as well as permanent herbaceous cover and tree planting on the three acres of high ground (Appendix A, Sheet 4).

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Thorpe Property Sediment Control Project December 30, 2014 WACF Kosciusko County, IN

III. Construction

Bidding took place in June 2014 and construction was awarded to Stanger Excavating for the low bid of $57,000.00. Construction of the basin and wetland enhancement began in November 2014 and was completed in early December 2014. Limited as-built survey data was taken following construction and used to create an as-built drawing for the record (Appendix C). During construction, an adjustment was made to proposed grade of the outlet due to the elevation of the agricultural tile invert. The planned spillway elevation was 884.0 with the invert of the buried drainage tile thought to be at 884.5. The tile invert elevation at the south edge of the basin was actually 882.1; therefore, the spillway elevation was lowered to 881.9 so that water would not back up into the drainage tile. The bottom elevation of the excavated basin averaged 876.0 with a maximum depth to 875.0 as per the plans. This leaves an expected average basin depth of six feet as planned. The enhancement of the wetland area downstream of the rock spillway encompassed approximately 0.2 acres excavated to a depth of one foot at an elevation of 881.3 on average. The controlling elevation where water leaves the WACF property beyond this enhancement area is 882.1, the same elevation as the drainage tile invert.

Other changes the contractor made during construction included eliminating the construction entrance. This was determined by the contractor to be unnecessary. The riprap inlet spillway was shifted to the east to avoid working over the clay drainage tile. The 12-inch diameter tile shown on the plans was actually an 18-inch diameter tile. The last 20 feet of that clay drainage tile was replaced with a new 20 foot section of corrugated plastic pipe. It was not pre-determined where all of the excavated earthen material would be disposed of on site. The contractor was given the option of blending it into adjacent grades or hauling off site. The contractor chose to blend the spoils into the existing grades. Much of the spoils were used to raise the grade of the easternmost swale; however, appropriate grades for drainage from the adjacent property were maintained. Other than the native seed required by the plans, the contractor seeded the entire 4 acres of disturbed soils on the site with a temporary winter rye mix. The 744 trees and permanent understory mix will be planted in spring 2015 per the plans.

A sandy substrate was exposed at the bottom of the otherwise silt loam surface layers. This sand substratum will result in near continuous infiltration to the ground water and the basin may never hold a permanent pool of six feet as planned. After a significant (3 inch) precipitation event during construction the basin topped out at a foot over the spillway, but within 24 hours the basin had drained down to just a foot of standing water in the lowest elevations. This is a best case scenario for trapping sediments as it allows for five feet of detention after each storm event. We believe that an emergent wetland will develop in the bottom of the basin creating good amphibian habitat. Over time, the bottom may seal due to silt and organics and once sealed the basin will turn into an open water pool at the elevation of the spillway. The permanent pool retention will still maintain some silt capturing ability but not as much as a detention basin. As an unregulated waterway WACF can choose to clean the basin at any time. Permanent benchmark elevations and constructed spot elevations are shown on the As-Built drawings to help determine the rate of basin filling in the future (Appendix C).

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Thorpe Property Sediment Control Project December 30, 2014 WACF Kosciusko County, IN

IV. SUMMARY The 4.51 acre Thorpe parcel located within the headwaters of the Martin drainage off CR 1000 E near State Road 13 in Kosciusko County, Indiana was purchased by WACF for the purpose of installing a project to reduce suspended sediments from entering Lake Wawasee. The parcel had 0.64 acres of existing wetland, and a topographic relief of 14 feet. The majority of off-site surface water drained through the southwest corner of the parcel. A sediment pond was designed to capture surface water from approximately 85 of the 120 acres draining into this parcel. The sediment pond is approximately ¾ acre with an average depth of six feet. The riprap spillway outlet is set an average elevation 0.5 feet below the invert of the drainage tile invert. The basin outlet spillway drains into 0.2 acres of enhanced wetland before entering the natural wetland on the north property boundary. Water will exit the property at the same elevation as the agricultural tile that drains water to the property. Tree planting and final seeding of the disturbed area that received excavated spoils will occur in the spring of 2015.

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APPENDIX A:

Project Plans

WACF THORPE PARCEL

KOSCIUSKO COUNTY, INDIANA

APPENDIX B:

Original Concept Plans

WACF THORPE PARCEL

KOSCIUSKO COUNTY, INDIANA

DECEMBER 2012Job No.1205127

DRAFT

Figure 1: CONCEPT PLAN4.51-AcreThorpe PropertyWACF (Wawasee Area Conservancy Foundation)Kosciusko County, Indiana

Section 27, Township 34 North, Range 7 East

708 Roosevelt Road, Walkerton, IN 46574Phone 574-586-3400 / Fax 574-586-3446

www.cardnojfnew.com

Existing Drainage Tile to be cut at basin or piped around basin

Existing Drainage Tile to be cut at basin or piped around basin

SedimentBasin

OverflowRock Chute

RockChute

Bioswale

Berm

Exisitng Wetland to be enhanced

Proposed Agri-Drain

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C o u n t y R o a d 1 0 0 0 N o r t h

Proposed Woodland

±Area of Interest

Existing Wetland (0.47 Acre +/-)

Existing Grade (2' contours)

Approximate Location Existing Drainage Tile

Proposed Grade (2' contours)

Proposed Agri-Drain

Proposed Berm

Proposed Rock Chute

Proposed Excavation for Bioswale

Proposed WoodlandPa

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The information presented in this map document is advisory and intended for reference purposes only.

Coordinate System: GCS WGS 1984Datum: WGS 1984Units: Degree

0 80 16040 Feet

Source: GPS Data Point - Field located by Cardno JFNew on August 28, 2012.

APPENDIX C:

As-Built Plans

WACF THORPE PARCEL

KOSCIUSKO COUNTY, INDIANA

WACF Thorpe Basin Final Report December 30, 2014 Page 1

Photographic Record- WACF Thorpe Project 2014

Before

Facing east from will become the spillway on the pond outlet, August 2012

Facing west-northwest (left) at the proposed pond outlet, and view of previous tile outlet (tile on right was abandoned version on tile on left, August 2012

WACF Thorpe Basin Final Report December 30, 2014 Page 2

Immediately following construction

Facing north from top of inlet spillway into completed detention pond, December 2014

Facing south at tile inlet into detention pond, December 2014

Facing south at outlet spillway of detention pond, December 2014 (Note high water marks)

WACF Thorpe Basin Final Report December 30, 2014 Page 3

Completed project December 16, 2014

Facing east-southeast from the west property boundary at north end of constructed basin

Facing Southeast to south from the west property boundary at north end of constructed basin

WACF Thorpe Basin Final Report December 30, 2014 Page 4

Completed Project- December 16, 2014

Facing south from spillway at inlet to basin (note one foot of standing water in bottom of basin)

Facing east through constructed outlet spillway into excavated wetland area.