January 14, 2008

Mark B. Joersz

ADS/Hancor Inc.

4640 Trueman Blvd.

Hilliard, OH 43026

RE: Approval of Water Quality Unit for Pretreatment

Dear Mr. Joersz,

This letter is to advise you the Metropolitan St. Louis Sewer District has provided

provisional use level approval to the ADS/Hancor Inc. – Water Quality Unit to

provide Pretreatment for other BMP’s in accordance with District requirements.

This device is provisionally approved only. Please submit a set of sample

calculations that demonstrates how your product will be incorporated with a sand

fi lter BMP and also a set of calculations on how it will be incorporated with a wet

pond BMP. Details of any further approvals may be based upon these calculations.

The initial installation of the ADS/Hancor Inc. – Water Quality Unit in the MSD

shall include the following:

1) A manufacturer’s or vendor’s representative must be onsite during the

proprietary BMP installation to ensure the product’s installation

requirements are met.

2) Shop drawings indicating elevations of fl owlines, weirs, pipe inverts, etc.

will be required prior to installation.

3) The manufacturer or vendor must arrange for an as-built survey of the

proprietary BMP to be performed by a Missouri-registered Professional

Land Surveyor once the device has been installed, and prior to any testing

or monitoring.

4) The manufacturer or vendor must perform quarterly inspections of the

proprietary BMP during its’ fi rst year of operation, which will include visual

inspections and quantitative analysis of the service’s sediment removal

effi ciency, especially as compared to its design effi ciency. MSD requests

to be invited to these inspections to further enhance familiarity and

understanding of the device.

5) Formal reports shall be submitted to MSD, including as-builts and at each

quarterly inspection. The reports shall include summaries, quantitative

analysis mentioned in item 4, photographs of the structure, inlet, internal

conditions of the structure, outfall conditions, etc. The reports shall also

evaluate the performance of the owner’s adherence to the approved

maintenance program, and offer suggestions for any areas of

improvement.

Provisional use level approval is only granted for a period of one (1) year from the date of

this letter. MSD reserves the ability to withdraw or modify this approval based on subsequent

information, including information indicating that this BMP does not satisfy MSD rules,

requirements, or construction specifi cations.

If you have any questions, please do not hesitate to contact me at (314) 768-2772.

Sincerely,

Michael T. Buechter, PE

Principal Engineer

Engineering/Design

ADS & HANCOR PRODUCTS MAKE STORMWATER MANAGEMENT EASIER IN ST. LOUIS

The St. Louis MSD now approves ADS & Hancor Water Quality Units, StormTech® Chambers, Pipe Detention Systems and FloGardTM Dual-Vortex Hydrodynamic Separators (DVS) for use in stormwater management. For more information please visit http://68.88.49.153/Eng/planreview/StormwaterBMPs.html.

Superior Engineering:ADS & Hancor drainage products provide the strength needed for tough applications. Products and innovative drainage systems such as Water Quality Units, StormTech chambers, pipe detention systems and FloGard DVS offer superior abrasion resistance and won’t rust or corrode like concrete or steel.

Easy Installations:The expert design of ADS & Hancor products makes them easier and more cost-effective to install. They

require fewer people, less time and less heavy equipment to install compared to the competition’s products. It all adds up to lower installation costs.

Outstanding Value:Drainage products from ADS & Hancor have many performance advantages over the competition…at a fraction of the cost.

Advanced Drainage Applications:ADS & Hancor products have many different uses and installations for stormwater management across the country. Multiple sizes and configurations allow for maximum flexibility. System design assistance is available for all your projects.

Advanced Drainage Systems® and the Green Stripe are registered trademarks of Advanced Drainage Systems, Inc. Hancor® is a registered trademark of Hancor, Inc. StormTech® is a registered trademark of StormTech, LLC. FloGard® DVS is a registered trademark of KriStar, Inc. © 2008 Advanced Drainage Systems, Inc. (08074) 02/08

ENGINEERED TO OUTPERfORM

1.888.367.7473 • www.hancor.com1.800.821.6710 • www.ads-pipe.com

SPECIAL ANNOUNCEMENT: ST. LOUIS MSD APPROVES ADS & HANCOR PRODUCTS FOR STORMWATER MANAGEMENT

See details inside.

ADS/Hancor, Inc. 401 Olive Street Findlay, OH 45840