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| Time Period            | Rentable Square Foot Rate | Annual Base Rent | Monthly Base Rent |
|------------------------|---------------------------|------------------|-------------------|
| EPCD – 5/31/11*  | $10.00                    | $33,730.00       | $2,810.83         |
| 6/1/11 – 5/31/12 | $10.25                    | $34,573.25       | $2,881.10         |
| 6/1/12 – 5/31/13 | $10.51                    | $35,450.23       | $2,954.19         |
| 6/1/13 – 5/31/14 | $10.77                    | $36,327.21       | $3,027.27         |
| 6/1/14 – 5/31/15 | $11.04                    | $37,237.92       | $3,103.16         |
| 6/1/15 – 5/31/16 | $11.32                    | $38,182.36       | $3,181.86         |
| 6/1/16 – 5/31/17 | $11.60                    | $39,126.80       | $3,260.57         |
| 6/1/17 – 5/31/18 | $11.89                    | $40,104.97       | $3,342.08         |
| 6/1/18 – 5/31/19 | $12.19                    | $41,116.87       | $3,426.41         |

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| ATTEST/WITNESS:                                                                                                                                                    |   | LANDLORD:                                                                                                                                                                                                                                                                                                                                                 |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|                                                                                                                                                               |   |                                                                                                                                                                                                                                                                                                                                                      |
|                                                                                                                                                               |   | FP STERLING PARK II, LLC,a Virginia limited liability companyBy:  First Potomac Realty Investment        Limited Partnership        Its Sole MemberBy:  First Potomac Realty Trust        Its General Partner |
| /s/ Joanie Courney                         |   | By: /s/ Mary T. Wacker                                                                                                                                                                                        |
| Joanie Courney                                                                                                                                                     |   | Name: Mary T. Wacker                                                                                                                                                                                     |
|                                                                                                                                                               |   | Title: Regional Vice President                                                                                                                                                                                                                                  |
|                                                                                                                                                               |   | Date: June 25, 2010                                                                                                                                                   |
|                                                                                                                                                               |   |                                                                                                                                                                                                                                                                                                                                                      |
|                                                                                                                                                               |   |                                                                                                                                                                                                                                                                                                                                                      |
| ATTEST/WITNESS:                                                                                                                                                    |   | TENANT:                                                                                                                                                                                                                                                                                                                                                   |
|                                                                                                                                                               |   |                                                                                                                                                                                                                                                                                                                                                      |
|                                                                                                                                                               |   | SUTRON CORPORATIONa Virginia corporation                                                                                                                                                                                                                                                                                                                  |
|                                                                                                                                                               |   |                                                                                                                                                                                                                                                                                                                                                      |
| /s/ Sidney C. Hooper                                                |   | By: /s/ Raul S. McQuivey                                                                                                                                                                                                     |
| Sidney C. Hooper                                                                                                                                                   |   | Name: Raul S. McQuivey                                                                                                                                                                                                       |
|                                                                                                                                                               |   | Title: Chief Executive Officer                                                                                                                                                                                                                             |
|                                                                                                                                                               |   | Date: 24 June 2010                                                                                                                                               |

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| ATTEST/WITNESS:                     |   | LANDLORD:                                                                                                                                                                                                                                                                                                                                      |
|-------------------------------------|--------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|                                |   | FP Sterling Park II, LLC,a Virginia Limited Liability Company By:  First Potomac Realty Investment Limited       Partnership       Its Sole MemberBy:  First Potomac Realty Trust       Its General Partner  |
| ___________________________________ |   | By:________________________________                                                                                                                                                                                                                                                                                                                 |
|                                |   | Name:______________________________                                                                                                                                                                                                                                                                                                                 |
|                                |   | Title:_______________________________                                                                                                                                                                                                                                                                                                               |
|                                |   | Date:_______________________________                                                                                                                                                                                                                                                                                                                |
|                                |   |                                                                                                                                                                                                                                                                                                                                                |
| ATTEST/WITNESS:                     |   | TENANT:                                                                                                                                                                                                                                                                                                                                        |
|                                |   | Sutron Corporation,                                                                                                                                                                                                                                                                                                                                 |
|                                |   | a Virginia Corporation                                                                                                                                                                                                                                                                                                                         |
| ___________________________________ |   | By:________________________________                                                                                                                                                                                                                                                                                                                 |
|                                |   | Name:______________________________                                                                                                                                                                                                                                                                                                                 |
|                                |   | Title:_______________________________                                                                                                                                                                                                                                                                                                               |
|                                |   | Date:_______________________________                                                                                                                                                                                                                                                                                                                |

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