Filing Details

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

o

Rule 13d-1(b)

x

Rule 13d-1(c)

o

Rule 13d-1(d)

CUSIP No. 147448104

1.

Names of Reporting Persons
Portolan Capital Management, LLC

2.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)

o

(b)

o

3.

SEC Use Only

4

Citizenship or Place of Organization
Delaware

Number of
Shares
Beneficially
Owned by
Each
Reporting
Person With

5.

Sole Voting Power
3,012,984

6.

Shared Voting Power

7.

Sole Dispositive Power
3,012,984

8.

Shared Dispositive Power

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
3,012,984

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  o

11.

Percent of Class Represented by Amount in Row (9)
7.44%

12.

Type of Reporting Person (See Instructions)
IA

CUSIP No. 147448104

1.

Names of Reporting Persons
George McCabe

2.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)

o

(b)

o

3.

SEC Use Only

4

Citizenship or Place of Organization
USA

Number of
Shares
Beneficially
Owned by
Each
Reporting
Person With

5.

Sole Voting Power
3,012,984

6.

Shared Voting Power

7.

Sole Dispositive Power
3,012,984

8.

Shared Dispositive Power

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
3,012,984

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  o

11.

Percent of Class Represented by Amount in Row (9)
7.44%

12.

Type of Reporting Person (See Instructions)
IN

Item 1.

(a)

Name of Issuer
Casella Waste Systems, Inc.

(b)

25 Greens Hill Lane

Rutland, VT 05701

Item 2.

(a)

Name of Person Filing
This statement is being filed with respect to the shares of common stock (Common Stock) of the Issuer beneficially owned (1) directly by Portolan Capital Management, LLC, a registered investment adviser, in its capacity as investment manager for various clients, and (2) indirectly by George McCabe, the Manager of Portolan Capital Management, LLC.  Portolan Capital Management, LLC and Mr. McCabe are sometimes individually referred to herein as a Reporting Person and collectively as the Reporting Persons.

(b)

Address of Principal Business Office or, if none, Residence
Portolan Capital Management, LLC and George McCabe

2 International Place, FL 26, Boston, MA 02110

(c)

Citizenship
Portolan Capital Management, LLC DE

Mr. McCabe - USA

(d)

Title of Class of Securities
Common

(e)

CUSIP Number
147448104

Item 3.

If this statement is filed pursuant to §§240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

(a)

o

Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o).

(b)

o

Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c).

(c)

o

Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c).

(d)

o

Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8).

(e)

o

An investment adviser in accordance with §240.13d-1(b)(1)(ii)(E);

(f)

o

An employee benefit plan or endowment fund in accordance with §240.13d-1(b)(1)(ii)(F);

(g)

o

A parent holding company or control person in accordance with §240.13d-1(b)(1)(ii)(G);

(h)

o

A savings association as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);

(i)

o

A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);

(j)

o

A non-U.S. institution in accordance with § 240.13d1(b)(1)(ii)(J);

(k)

o

Group, in accordance with § 240.13d-1(b)(1)(ii)(J).

Item 4.

Ownership

Provide the following information regarding the aggregate number and percentage of the class of securities of the issuer identified in Item 1.

Reference is hereby made to Items 5-9 and 11 of pages 1 - 2 of this Schedule, which Items are incorporated by reference herein.

Item 5.

Ownership of Five Percent or Less of a Class

If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following   o.

Not applicable

Item 6.

Ownership of More than Five Percent on Behalf of Another Person

Various persons have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the Common Stock of Casella Waste Systems, Inc.  No one persons interest in the Common Stock of Casella Waste Systems, Inc. is more than five percent of the total outstanding Common Stock.

Item 7.

Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company or Control Person

Not applicable

Item 8.

Identification and Classification of Members of the Group

Not applicable

Item 9.

Notice of Dissolution of Group

Not applicable

Item 10.

Certification

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

February 3, 2017

Date

Portolan Capital Management, LLC

By: 

/s/ George McCabe

George McCabe, Manager

/s/ George McCabe

George McCabe

ATTENTION

Intentional misstatements or omissions of fact constitute Federal Criminal Violations (See 18 U.S.C. 1001).