Exhibit 10.18A

ADVANCED DRAINAGE SYSTEMS, INC.

Incentive Stock Option Agreement

This Incentive Stock Option Agreement is entered into as of                 ,
between Advanced Drainage Systems, Inc., a Delaware corporation (the “Company”),
and                 (the “Optionee”).

§1. Grant of Option. Pursuant to the Advanced Drainage Systems, Inc. Amended
2000 Incentive Stock Option Plan (the “Plan”) and authorization by the Board of
Directors of the Company, the Company hereby grants to the Optionee an option
(the “Option”) to purchase a total of                 (            ) shares (the
“Option Shares”) of the $.01 par value Common Stock of the Company (“Stock”), at
the price and on the other terms and conditions hereinafter set forth.

§2. Option Price. The Option shall be exercisable at a price of                
Dollars ($        ) per share.

§3. Exercise Period. Subject to the terms and conditions hereinafter set forth
and except as provided in §§10, 11, 12(a) and 13 of this agreement, the Option
shall be exercisable as follows:

(a) The Optionee shall be entitled to purchase up to one-third of the Option
Shares if the Optionee remains continuously in the employ of the Company, or any
subsidiary thereof, for five years from the date hereof.

(b) The Optionee shall be entitled to purchase up to two-thirds of the Option
Shares if the Optionee remains continuously in the employ of the Company, or any
subsidiary thereof, for six years from the date hereof.

(c) The Optionee shall be entitled to purchase all of the Option Shares if the
Optionee remains continuously in the employ of the Company, or any subsidiary
thereof, for seven years from the date hereof.

The Optionee’s right to purchase the Option Shares shall continue through, and
may not be exercised after,                 (the “Expiration Date”).

§4. Exercise of Option. The Option shall be exercised by delivery to the Company
of a written statement in form and substance satisfactory to the Board of
Directors of the Company (the “Exercise Form”).

§5. Execution of Executive Responsibility Agreement. The grant of the Option
pursuant to §1 of this agreement shall be contingent upon the execution by the
Optionee of an Executive Responsibility Agreement with the Company in form and
substance satisfactory to the President of the Company, if such an Executive
Responsibility Agreement has not already been executed.

§6. Execution of Stockholders’ Agreement. [Intentionally Omitted].

 

- 1 -

--------------------------------------------------------------------------------

§7. Payment of Option Price. At the time of exercise of the Option, the Optionee
shall pay the entire option price for the Option Shares being purchased (a) in
cash or by check, (b) in Stock or (c) in any combination of cash, check and
Stock. The Board, in its sole discretion, shall establish the value of any Stock
that is used in payment of the option price. Upon receipt of the entire option
price for the Stock being purchased and compliance by the Optionee with any
other applicable requirements hereunder, the Company shall forthwith cause
certificates for such Stock to be delivered to the Optionee.

§8. Compliance with Securities Laws. In all cases, the exercise of the Option
(in whole or in part) and the issuance of Stock pursuant thereto shall be
contingent upon the prior registration or exemption therefrom of such Stock
under the Securities Act of 1933 and such state laws as may be applicable, or a
determination by counsel for the Company that the issuance of such Stock will be
a transaction exempt from such registration.

§9. Non-transferability and Termination of Option Privileges. Except as
otherwise provided in §10, the Option shall not be transferable or assignable
and, during the Optionee’s lifetime, shall be exercisable solely by the
Optionee. Further, except as otherwise provided in §§10, 11 and 12, the Option
shall cease and terminate upon termination of the Optionee’s employment with the
Company and its subsidiaries for any reason.

§10. Death of Optionee. If the Optionee shall die while in the employ of the
Company or any of its subsidiaries, the provisions of §§3(a), 3(b) and 3(c)
shall have no force and effect and the Option may be exercised with respect to
all of the Option Shares during the one-year period commencing on the date of
the Optionee’s death by the Optionee’s personal representative or by any person
who acquires the Option by bequest or inheritance as a result of the Optionee’s
death; provided, however, that no exercise may take place after the Expiration
Date.

§11. Disability of Optionee. If the Optionee shall become permanently and
totally disabled within the meaning of §22(e)(3) of the Internal Revenue Code of
1986, as amended, while in the employ of the Company or any of its subsidiaries,
the provisions of §§3(a), 3(b) and 3(c) shall have no force and effect and the
Option may be exercised by the Optionee with respect to all of the Option Shares
during the one-year period commencing on the date of such permanent and total
disability; provided, however, that no exercise may take place after the
Expiration Date.

§12. Other Termination of Employment.

(a) Unless expressly provided otherwise in a written agreement between the
Optionee and the Company (or any subsidiary thereof), the Optionee’s employment
with the Company or any subsidiary thereof is and at all times has been at will.
Nothing in this agreement is intended to and no action taken pursuant to this
agreement will change the at-will nature of the employment relationship.

(b) If the Optionee’s employment with the Company or any subsidiary thereof is
terminated by the Company for Cause, the Option shall be deemed to have
terminated as of the day before the date on which the Company notifies the
Optionee of the

 

- 2 -

--------------------------------------------------------------------------------

Optionee’s termination. The term “Cause” shall mean any illegal or disreputable
or malfeasant conduct which in any significant respect impairs the reputation,
goodwill or business position of the Company or involves the Company’s funds or
other assets.

(c) If the Optionee shall cease to be employed by the Company and its
subsidiaries for any reason other than Cause, death or permanent and total
disability within the meaning of §22(e)(3) of the Internal Revenue Code of 1986,
as amended, the Option may be exercised by the Optionee, to the extent permitted
by §§3(a), 3(b) and 3(c), during the three-month period commencing on the date
on which the Optionee’s employment terminates; provided, however, that no
exercise may take place after the Expiration Date.

§13. Other Events. If the Optionee remains continuously in the employment of the
Company, or any subsidiary thereof, the provisions of §§3(a), 3(b) and 3(c)
shall have no force and effect and the Option may be exercised by the Optionee
with respect to all of the Option Shares commencing at the time of a “Change in
Control”; provided, however, that no exercise may take place after the
Expiration Date. For purposes of this provision, a Change in Control shall have
occurred if, at any time after the Option is granted and before the Expiration
Date, any of the following events shall have occurred: (i) the Company enters
into an agreement to merge, consolidate or reorganize into or with another
corporation or other legal person, and as a result of such merger, consolidation
or reorganization less than 51% of the combined voting power of the
then-outstanding securities of such corporation or person immediately after such
transaction will be held in the aggregate by officers, directors and holders of
a beneficial interest in voting securities of the Company immediately prior to
such transaction; (ii) the Company enters into an agreement to sell or otherwise
transfer all or substantially all of its assets to any other corporation or
other legal person, and as a result of such sale or transfer a beneficial
interest in less than 51% of the combined voting power of the then-outstanding
securities of such corporation or person immediately after such sale or transfer
is held in the aggregate by officers, directors and holders of a beneficial
interest in voting securities of the Company immediately prior to such sale or
transfer; or (iii) during any continuous 12-month period stockholders of the
Company sell or enter into an agreement or agreements to sell to anyone other
than the Company securities of the Company representing 50% or more of the
combined voting power of the Company at the beginning of such 12-month period.

§14. Adjustment for Stock Dividend or Stock Split. In the event that a dividend
is hereafter paid on outstanding shares of Stock in shares of Stock, or in the
event that the number of outstanding shares of Stock is hereafter increased as a
result of a stock split, and the Option is then unexercised (in whole or in
part), the number of Option Shares shall thereupon be increased to include the
number of shares of Stock which would have been distributed with respect to the
shares of Stock subject to the unexercised portion of the Option if such shares
of Stock had been outstanding at the time of the dividend or stock split, and
the option price per share shall be adjusted to reflect such increased number of
Option Shares.

§15. Adjustment for Reorganization or Merger. In the event that outstanding
shares of Stock are hereafter changed into or exchanged for a different number
or kind of shares of stock or securities of the Company or of another
corporation or corporations, whether as a result of a reorganization,
recapitalization, reclassification, merger, consolidation or otherwise, and the

 

- 3 -

--------------------------------------------------------------------------------

Option is then unexercised (in whole or in part), the Option and the option
price shall thereupon be adjusted to apply to the number and kind of shares of
stock or securities which would have been received for the shares of Stock
subject to the unexercised portion of the Option if such shares of Stock had
been outstanding at the time of such reorganization, recapitalization,
reclassification, merger, consolidation or other event.

§16. Additional Adjustments. In the event that there is any change in the
corporate structure or outstanding shares of Stock or any other transaction for
which an adjustment is not provided by §§14 or 15 of this agreement, and the
Option is then unexercised (in whole or in part), the Board of Directors of the
Company may, in its sole discretion, require an adjustment in the number or kind
of shares of stock or securities subject to the Option or the option price and
such adjustment shall be binding and effective for all purposes hereof.

§17. Elimination of Fractional Shares. Any addition or adjustment provided for
in §§14, 15 or 16 of this agreement may be limited to the extent necessary to
prevent fractions of shares from becoming available under the Option.

§18. Optionee Bound by Plan. The Optionee hereby acknowledges receipt of a copy
of the Plan and agrees to be bound by all applicable provisions thereof. If any
of the terms and provisions of this agreement are inconsistent or in conflict
with the terms and provisions of the Plan, the Plan shall supersede and prevail
over such inconsistent provisions hereof.

§19. No Obligation. There is no obligation on the Optionee to exercise any
option.

§20. Withholding. To the extent (if any) that this Option, when exercised, is
treated as a non-statutory stock option and not as an incentive stock option
within the meaning of §422 of the Internal Revenue Code, the Optionee agrees
that the Optionee shall make such arrangements as are satisfactory to the
Company for withholding of federal, state, and local income and employment taxes
associated with such exercise. The Company agrees that, at the Optionee’s
request, the Company shall permit the Optionee to satisfy all or part of such
withholding requirements through the Company’s withholding from the Optionee of
that number of shares of Stock otherwise deliverable upon the exercise of this
Option equal in value to the aggregate amount of withholding that the Optionee
wishes to satisfy through the Company’s retention of Stock. The Optionee shall
be permitted to satisfy all or any portion of the Optionee’s total income and
employment tax liability associated with the exercise of the non-statutory stock
portion of this Option through the withholding of shares, even if such total tax
liability shall exceed the minimum tax withholding required by law. The Board,
in its sole discretion, shall establish the value of any Stock that is so
withheld. The Optionee and the Company agree that any such withheld shares shall
be treated, for all purposes, as if they were acquired by the Optionee upon
exercise of this Option and then immediately sold by the Optionee to the Company
at their fair market value.

§21. Headings. The headings of the sections of this agreement are inserted for
convenience only and shall not be deemed to be part hereof.

[Signature Page Follows]

 

- 4 -

--------------------------------------------------------------------------------

IN WITNESS WHEREOF, the parties have executed multiple counterparts of this
agreement, each of which shall be deemed to be an original, as of the date first
set forth above.

 

Optionee:     ADVANCED DRAINAGE SYSTEMS, INC.

 

    By:  

 

                    (Name)                             (Office)

 

- 5 -