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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="5" face="Times New Roman" style="font-size:16.0pt;font-weight:bold;">UNITED STATES</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="5" face="Times New Roman" style="font-size:16.0pt;font-weight:bold;">SECURITIES AND EXCHANGE COMMISSION</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">WASHINGTON, D.C.&#160; 20549</font></b></p>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="5" face="Times New Roman" style="font-size:16.0pt;font-weight:bold;">FORM&nbsp;8-K</font></b></p>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">CURRENT&#160; REPORT</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">Pursuant to Section&nbsp;13 or 15(d)&nbsp;of the Securities Exchange Act of 1934</font></b></p>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Date of Report (Date of earliest event reported):</font></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="2" face="Times New Roman" style="font-size:10.0pt;font-weight:bold;">September&nbsp;27, 2013</font></b></p>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="5" face="Times New Roman" style="font-size:16.0pt;font-weight:bold;">TETRA TECH,&nbsp;INC.</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Exact name of registrant as specified in its charter)</font></p>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">Delaware</font></b></p>    </td>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">0-19655</font></b></p>    </td>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">95-4148514</font></b></p>    </td>   </tr>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(State or other jurisdiction</font></p>    </td>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Commission</font></p>    </td>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(IRS Employer</font></p>    </td>   </tr>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">of&nbsp;incorporation)</font></p>    </td>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">File Number)</font></p>    </td>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Identification&nbsp;Number)</font></p>    </td>   </tr>  </table>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">3475 East Foothill Boulevard, Pasadena, California&#160; 91107</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Address of principal executive office, including zip code)</font></p>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">(626) 351-4664</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Registrant&#146;s telephone number, including area code)</font></p>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">Not Applicable</font></b></p>
<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">(Former name or former address, if changed since last report)</font></p>
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<p style="margin:0in 0in .0001pt;text-align:justify;"><font size="2" face="Times New Roman" style="font-size:10.0pt;">Check the appropriate box below if the Form&nbsp;8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:</font></p>
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<p style="margin:0in 0in .0001pt;"><font size="3" face="Wingdings" style="font-size:12.0pt;">o</font><font size="2" style="font-size:10.0pt;">&#160;&#160; Written communications pursuant to Rule&nbsp;425 under the Securities Act (17 CFR 230.425)</font></p>
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<p style="margin:0in 0in .0001pt;"><font size="3" face="Wingdings" style="font-size:12.0pt;">o</font><font size="2" style="font-size:10.0pt;">&#160;&#160; Soliciting material pursuant to Rule&nbsp;14a-12 under the Exchange Act (17 CFR 240.14a-12)</font></p>
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<p style="margin:0in 0in .0001pt .25in;text-indent:-.25in;"><font size="3" face="Wingdings" style="font-size:12.0pt;">o</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font><font size="2" style="font-size:10.0pt;">Pre-commencement communications pursuant to Rule&nbsp;14d-2(b)&nbsp;under the Exchange Act (17&nbsp;CFR&nbsp;240.14d-2(b))</font></p>
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<p style="margin:0in 0in .0001pt .25in;text-indent:-.25in;"><font size="3" face="Wingdings" style="font-size:12.0pt;">o</font><font size="1" style="font-size:3.0pt;">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; </font><font size="2" style="font-size:10.0pt;">Pre-commencement communications pursuant to Rule&nbsp;13e-4(c)&nbsp;under the Exchange Act (17&nbsp;CFR&nbsp;240.13e-4(c))</font></p>
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<p style="margin:0in 0in .0001pt;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">Item   1.01.</font></b></p>    </td>
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<p style="margin:0in 0in .0001pt;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">Entry   into a Material Definitive Agreement.</font></b></p>    </td>   </tr>  </table>
<p style="margin:0in 0in .0001pt;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">&nbsp;</font></p>
<p style="margin:0in 0in .0001pt;text-align:justify;text-indent:.5in;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">On September&nbsp;27, 2013, Tetra Tech,&nbsp;Inc. (the &#147;Company&#148;) entered into Amendment No.&nbsp;1 (&#147;Amendment No.&nbsp;1&#148;) to its Amended and Restated Credit Agreement, dated as of May&nbsp;7, 2013, among the Company, Tetra Tech Canada Holding Corporation, Bank of America, N.A., as Administrative Agent, and the lenders party thereto (the &#147;Credit Agreement&#148;).&#160; The purpose of Amendment No.&nbsp;1 is to amend the definition of &#147;Consolidated EBITDA&#148; for purposes of the financial covenants contained in the Credit Agreement to add back to &#147;Consolidated Net Income&#148; for the fiscal quarters ending September&nbsp;29, 2013, December&nbsp;29, 2013 and March&nbsp;30, 2014 (i)&nbsp;up to $34,000,000 in non-recurring charges incurred during the fiscal quarter ended June&nbsp;30, 2013 in connection with corporate restructurings and (ii)&nbsp;up to $36,000,000 in non-cash charges incurred during the fiscal quarter ended June&nbsp;30 2013 in connection with the &#147;Four Programs&#148; referenced in the Company&#146;s Form&nbsp;8-Ks, filed with the Securities and Exchange Commission on June&nbsp;18, 2013 and August&nbsp;7, 2013, and Form&nbsp;10-Q for the fiscal quarter ended June&nbsp;30, 2013.&#160; Amendment No.&nbsp;1 also provides that Consolidated EBITDA will be calculated without giving effect to the add-backs referenced above for purposes of determining the Company&#146;s &#147;Applicable Rate&#148; in effect at any time.</font></p>
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<p style="margin:0in 0in .0001pt;text-align:justify;text-indent:.5in;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">Amendment No.&nbsp;1 is attached hereto as Exhibit&nbsp;10.1 and is incorporated herein by reference.&#160; The description of Amendment No.&nbsp;1 contained herein is qualified in its entirety by reference to the full text of that agreement.</font></p>
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<p style="margin:0in 0in .0001pt;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">Financial   Statements and Exhibits.</font></b></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;text-indent:.5in;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">(d)</font></p>    </td>
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<p style="margin:0in 0in .0001pt;"><font size="3" face="Times New Roman" style="font-size:1.0pt;">&nbsp;</font></p>    </td>
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<p style="margin:0in 0in .0001pt;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">10.1</font></p>    </td>
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<p style="margin:0in 0in .0001pt;text-align:justify;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">Amendment   No.&nbsp;1 dated as of September&nbsp;27, 2013 to the Amended and Restated   Credit Agreement dated as of May&nbsp;7, 2013 among Tetra Tech,&nbsp;Inc.,   Tetra Tech Canada Holding Corporation, the lenders party thereto and Bank of   America, N.A., as Administrative Agent.</font></p>    </td>   </tr>  </table>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">2<a name="PB_2_001728_7056"></a></font></p>
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<p align="center" style="margin:0in 0in .0001pt;text-align:center;"><b><font size="3" face="Times New Roman" style="font-size:12.0pt;font-weight:bold;">SIGNATURES</font></b></p>
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<p style="margin:0in 0in .0001pt;text-align:justify;text-indent:1.0in;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">Pursuant to the requirements of the Securities Exchange Act of 1934, the&nbsp;registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.</font></p>
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<p style="margin:0in 0in .0001pt;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">TETRA TECH,&nbsp;INC.</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt 10.0pt;text-indent:-10.0pt;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">Date:<u>&nbsp;&nbsp;&nbsp;September&nbsp;27,   2013&nbsp;&nbsp;&nbsp;&nbsp;</u></font></p>    </td>
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<p style="margin:0in 0in .0001pt;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">By:</font></p>    </td>
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<p style="margin:0in 0in .0001pt;"><u><font size="3" face="Times New Roman" style="font-size:12.0pt;">/S/ STEVEN M. BURDICK&nbsp;&nbsp;&nbsp;&nbsp;</font></u></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">Steven M. Burdick</font></p>    </td>   </tr>
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<p style="margin:0in 0in .0001pt;"><font size="3" face="Times New Roman" style="font-size:12.0pt;">Executive Vice   President and Chief <br>   Financial Officer</font></p>    </td>   </tr>  </table>
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{"company-data": {"conformed-name": "TETRA TECH INC", "cik": "0000831641", "assigned-sic": "8711", "irs-number": "954148514", "state-of-incorporation": "DE", "fiscal-year-end": "0928"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "000-19655", "film-number": "131121037"}, "business-address": {"street1": "3475 EAST FOOTHILL BOULEVARD", "city": "PASADENA", "state": "CA", "zip": "91107", "phone": "6263514664"}, "mail-address": {"street1": "3475 EAST FOOTHILL BOULEVARD", "city": "PASADENA", "state": "CA", "zip": "91107"}}
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C.  20549
FORM 8-K
CURRENT  REPORT
Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934
Date of Report (Date of earliest event reported):
September 27, 2013
TETRA TECH, INC.
(Exact name of registrant as specified in its charter)
Delaware
0-19655
95-4148514
(State or other jurisdiction
(Commission
(IRS Employer
of incorporation)
File Number)
Identification Number)
3475 East Foothill Boulevard, Pasadena, California  91107
(Address of principal executive office, including zip code)
(626) 351-4664
(Registrant's telephone number, including area code)
Not Applicable
(Former name or former address, if changed since last report)
Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:
o
Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
o
Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
o
Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
o
Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))
Item   1.01.
Entry   into a Material Definitive Agreement.
On September 27, 2013, Tetra Tech, Inc. (the "Company") entered into Amendment No. 1 ("Amendment No. 1") to its Amended and Restated Credit Agreement, dated as of May 7, 2013, among the Company, Tetra Tech Canada Holding Corporation, Bank of America, N.A., as Administrative Agent, and the lenders party thereto (the "Credit Agreement").  The purpose of Amendment No. 1 is to amend the definition of "Consolidated EBITDA" for purposes of the financial covenants contained in the Credit Agreement to add back to "Consolidated Net Income" for the fiscal quarters ending September 29, 2013, December 29, 2013 and March 30, 2014 (i) up to $34,000,000 in non-recurring charges incurred during the fiscal quarter ended June 30, 2013 in connection with corporate restructurings and (ii) up to $36,000,000 in non-cash charges incurred during the fiscal quarter ended June 30 2013 in connection with the "Four Programs" referenced in the Company's Form 8-Ks, filed with the Securities and Exchange Commission on June 18, 2013 and August 7, 2013, and Form 10-Q for the fiscal quarter ended June 30, 2013.  Amendment No. 1 also provides that Consolidated EBITDA will be calculated without giving effect to the add-backs referenced above for purposes of determining the Company's "Applicable Rate" in effect at any time.
Amendment No. 1 is attached hereto as Exhibit 10.1 and is incorporated herein by reference.  The description of Amendment No. 1 contained herein is qualified in its entirety by reference to the full text of that agreement.
Item   9.01.
Financial   Statements and Exhibits.
(d)
Exhibits
10.1
Amendment   No. 1 dated as of September 27, 2013 to the Amended and Restated   Credit Agreement dated as of May 7, 2013 among Tetra Tech, Inc.,   Tetra Tech Canada Holding Corporation, the lenders party thereto and Bank of   America, N.A., as Administrative Agent.
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SIGNATURES
Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.
TETRA TECH, INC.
Date:
September 27,   2013
By:
/S/ STEVEN M. BURDICK
Steven M. Burdick
Executive Vice   President and Chief
Financial Officer
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