<PAGE>
                                                            Exhibit 10.10.6

                                     
                                     
                                  O'BRIEN
                               ENVIRONMENTAL
                                  ENERGY
                               [Letterhead]

July 21, 1994

Mr. William L. Bardeen
Senior Vice President and Group Executive
Consumer Energy Services Group
PECO Energy Company
2301 Market Street
P.O. Box 8699
Philadelphia, PA 19101-8699


Re: Letter  Agreement Regarding Amendment of the Energy Service  Agreements
    between  the  Philadelphia Municipal Authority and O'BRIEN Philadelphia
    Cogeneration  Inc.  in  Conjunction  with  the  Execution  of  Economic
    Efficiency  Rider  Contracts  Between the City  of  Philadelphia  Water
    Department and PECO Energy Company.

Dear Bill:

This  letter  sets forth the terms and conditions agreed to by PECO  Energy
Company  ("PECO") and O'BRIEN Environmental Energy, Inc. ("O'BRIEN")  under
which,  (i)  O'BRIEN  will agree to seek amendments to the  Energy  Service
Agreements  ("ESAs") between the Philadelphia Municipal  Authority  ("PMA")
and  O'BRIEN  Philadelphia  Cogeneration Inc.  ("OPCI")  under  which  OPCI
currently  provides standby electric generating services for  the  City  of
Philadelphia Water Department ("PWD") at its Northeast and Southwest  waste
water  treatment facilities, and, (ii) PECO will offer and agree  to  enter
into  new  Economic  Efficiency Rider contracts with  the  PWD  that  would
provide the PWD with the same level of economic benefits the PWD would have
otherwise received from OPCI under the ESAs.

The agreed upon terms and conditions are as follows:

1.   PECO  will loan O'BRIEN $5.5 million (the "Loan") on August  5,  1995,
     the  last  date  of  O'BRIEN's final option period to  repurchase  the
     common  stock  of OPCI (the "Stock Repurchase") from OPC  Acquisition,
     Inc.  (OPCAI).   O'BRIEN will use $5 million of the Loan  proceeds  or
     such  lesser amount as may be mutually agreed to by O'BRIEN and  OPCAI
     to  purchase the OPCI common stock (the "Stock Repurchase Price")  and
     will  assign the OPCI common stock to PECO as collateral for the Loan,
     as  described  below.   PECO will facilitate the Stock  Repurchase  by
     wining  the  Stock  Repurchase Price directly to OPCAI  on  behalf  of
     O'BRIEN.  Until the Loan is repaid, O'BRIEN will make monthly payments
     of  $116,000  (the Monthly PECO Loan Payment) to PECO as  provided  in
     Schedule  1  attached  hereto.  O'BRIEN  may  prepay  the  outstanding
     balance of the Loan at any

<PAGE>

                                  O'BRIEN
                               ENVIRONMENTAL
                                  ENERGY
                               [Letterhead]

Mr. William L. Bardeen
July 21, 1994
Page 2



     time  without  penalty.  As further collateral for the  Loan,  O'BRIEN
     promises  to establish a lock-box arrangement with a bank,  acceptable
     to  PECO  and  paid for by O'BRIEN, as described in  the  addendum  to
     Schedule  2 attached hereto, under which all service fees received  by
     OPCI  from  PMA  will be directly deposited and all OPCI  obligations,
     including full payment to PECO, as provided in Schedule 1, are paid in
     accordance  with  the  Order  of  Monthly  Service  Fee  Distributions
     attached hereto as Schedule 2. Interest shall accumulate on any unpaid
     balance  (the  Unpaid  Balance) until paid  in  full.   If  there  are
     insufficient  funds available in any month to make the  total  Monthly
     PECO Loan Payment, or if there are excess funds available in any month
     after  all  the  obligations of Schedule 2 have  been  satisfied,  the
     remaining  principal  amount shall be adjusted and  the  term  of  the
     Schedule 1 Loan Amortization Table shall be extended or shortened,  as
     the  case  may be, to amortize the adjusted principal amount  using  a
     monthly payment of $116,000 and 12% annual interest rate.

     Further  O'BRIEN  will  not sell, move, pledge, or  otherwise  further
     encumber  the 22 megawatts of diesel fuel standby electric  generating
     equipment  sets  (the "Gen Sets") currently leased by  O'Brien  Rental
     Services ("RENTAL") to OPCI and located on PWD property without either
     obtaining  PECO's prior written approval or by repaying  the  Loan  in
     full.   Further,upon  the  effective date of  this  Letter  Agreement,
     O'BRIEN  will immediately use its best efforts to grant PECO a  second
     lien  or  mortgage on the Gen Sets in an amount equal  to  any  Unpaid
     Balance due on the Loan.  O'BRIEN will use its best efforts to  obtain
     the  consent  of the lenders who have a primary lien on the  Gen  Sets
     (the "Primary Lenders") if such consent is necessary to permit O'BRIEN
     to  grant the second lien to PECO.  O'BRIEN represents that, (i) as of
     the  date of this Letter Agreement, the projected schedule of payments
     would result in a remaining balance of less than $600,000 that will be
     owed to the Primary Lenders on all of the Gen Sets as of August, 1998,
     and  (ii)  the  original financing costs of the Gen Sets  and  related
     equipment  were  greater than $8 million.  O'BRIEN will  provide  PECO
     with  detailed  schedules and other documents  memorializing  RENTAL's
     obligations to the Primary Lenders with respect to the Gen  Sets  upon
     request.

2.   O'BRIEN will not sell or pledge the common stock of OPCI to any  party
     other  than PECO until the Loan is repaid in full, except that O'BRIEN
     may sell the common stock to OPCAI as provided in paragraph 5 below.

3.   Subject to a right of first refusal on the sale of the OPC I common
     stock which OPCAI has pursuant to Section 5 of Annex 11 to the Stock
     Purchase Agreement by and among OPCAI and affiliates and O'BRIEN dated
     November 12, 1993 (the "OPCAI Agreement"), after O'BRIEN has acquired
     the OPCI common stock, O'BRIEN shall grant PECO an exclusive option to
     acquire the OPCI common stock for the sum of $3 million, which option
     PECO must exercise when, and only if, all of the following conditions
     are satisfied:

(1)  O'BRIEN and the PMA execute amended ESAs that include at least the
     terms

<PAGE>

                                  O'BRIEN
                               ENVIRONMENTAL
                                  ENERGY
                               [Letterhead]

Mr. William L. Bardeen
July 21, 1994
Page 3

     described below in paragraph 10, and the ESAs are acceptable to PECO;

(2)  PECO and the PWD execute Economic Efficiency Rider Contracts (the "EER
     contracts"), as described below in paragraphs 7 and 8;

(3)  O'BRIEN   and  PECO  execute  a  transfer  agreement  (the   "Transfer
     Agreement"), as described below in paragraph 1 0; and

(4)  PECO  pays  the difference between $9.5 million and the  then  current
     balance on the Loan to O'BRIEN and deems the Loan satisfied in full.

4.   After  O'BRIEN has acquired the common stock of OPCI, PECO shall  have
     the right to tender an offer to purchase the OPCI common stock for  $3
     million  (the "Offer"), which offer shall be subject to the conditions
     described above in paragraph 3.

5.   If  OPCAI,  (i)  exercises its rights to match the  Offer,  (ii)  pays
     O'BRIEN  $3 million for the OPCI common stock in accordance  with  the
     OPCAI  Agreement,  and (iii) makes the Lease Buyout  Payment  of  $6.5
     million,  O'BRIEN shall immediately repay the Loan in  full  from  the
     proceeds of the payments received from OPCAI for the OPCI common stock
     and  the  Lease Buyout and shall do so by requesting that  OPCAI  wire
     directly to PECO an amount equal to the principal and interest due  on
     the Loan.

6.   If  OPCAI does not exercise its right to match, as soon as practicable
     and  at least thirty days after the date the Loan is executed, O'BRIEN
     and  PECO  shall  contact PWD and other relevant City of  Philadelphia
     representatives to seek PWD's agreement to an amendment of the ESAs as
     described  in paragraph 3 (1) above, the Transfer Agreement  described
     in paragraph 10 below, and the EER contracts as described in paragraph
     7  below.   O'BRIEN and its affiliates shall fully defend,  indemnify,
     and  hold  PECO harmless from and against any losses or  damages  that
     PECO  might suffer as the result of any legal action of any  kind,  if
     any, brought by OPCAI, or by any other person or entity making a claim
     based on the OPCAI Agreement, in connection with alleged violations of
     rights,  or alleged breaches of obligations, established by the  OPCAI
     Agreement,

7.   PECO  will  offer  EER  contracts to the PWID for  its  Northeast  and
     Southwest waste water treatment facilities that would provide the same
     level of economic benefits that the PWID would otherwise receive under
     the  ESAs.   The EER contracts will provide a discount on PECO's  full
     Rate  HT  service to the PWD in a manner that is consistent  with  the
     requirements of PECO's EER Tariff and the Pennsylvania Public  Utility
     Code.   The  combination  of this discount  and  the  timing  of  such
     discount will provide the same level of economic benefits that the PWD
     would  have otherwise received at the PWID facilities from OPCI  under
     the ESAs.

<PAGE>

                                  O'BRIEN
                               ENVIRONMENTAL
                                  ENERGY
                               [Letterhead]

Mr. William L. Bardeen
July 21, 1994
Page 4

8.   The  EER  contracts may include provisions similar to those provisions
     relating  to  early  termination contained in the "Term  of  Contract"
     section  of  the  EER  contract executed  on  June  30,  1994  between
     SmithKline Beecham Corporation and PECO if the PWD wishes to have such
     provisions included.

9.   O'BRIEN  and  PECO  shall cooperate to obtain PWD's agreement  to  the
     changes  to the ESAs, to accept the transfer of obligations previously
     owed  to  the PWD by OPCI to O'BRIEN, and to induce the PWD  to  enter
     into  the EER contracts on the terms and conditions described  herein,
     and  shall  endeavor  to  share any additional  burdens,  economic  or
     otherwise, which O'BRIEN and PECO deem reasonable and appropriate,  to
     bring  about  PWD's agreement and participation.  O'BRIEN  shall  have
     sole  discretion  to decide whether to accept any  such  burdens  with
     respect  to  the amended ESAs, and PECO shall have sole discretion  to
     decide  whether  to accept any such burdens with respect  to  the  EER
     contracts.

10.  The  amendment to the ESAs shall include provisions that,  (i)  permit
     the  PMA  or  PWD  to enter into the EER contracts, and  (ii)  release
     O'BRIEN or an affiliate of O'BRIEN from its obligation to maintain and
     operate   all  diesel  fuel  standby  electric  generating   equipment
     currently located on PWD property.  The amendment to the ESAs and  the
     Transfer  Agreement  between  PECO  and  O'BRIEN  will  contain  terms
     ensuring that, upon closing of those agreements and the EER contracts,
     (i)  OPCI shall have no remaining obligations whatsoever to the PIVIA,
     the  PWD,  or  to O'BRIEN and any of its affiliates, or to  any  other
     person  or  entity, and, (H) that O'BRIEN will assume any  obligations
     that  OPCI  had  to the PIVIA, the PWD or to O'BRIEN and  any  of  its
     affiliates,  or to any other person or entity, it being PECO's  intent
     to  take whatever actions that may be necessary to cause OPCI to cease
     to  exist  immediately following the execution of  the  amended  ESAs,
     Transfer Agreement, and the EER contracts.

11.  If the PMA fails to execute the amended ESAs and the EER contracts
     within 120 days after the date the Loan is made, PECO may issue a
     second offer to purchase the common stock according to the same terms
     and conditions as its first offer, as described above in paragraphs 3,
     4 and 5.

12.  On,  or  as soon as practicable after, the date on which there  is  no
     longer  any  possibility  that  the amended  ESAs  and  EER  contracts
     contemplated  herein  will  be successfully negotiated  and  executed,
     O'BRIEN and RENTAL shall enter into a written security agreement  (the
     "Security Agreement") with PECO that will obligate O'BRIEN and  RENTAL
     to,  within  six  (6) months of the date the ESAs are terminated  (the
     "Final  Repayment Date"), (i) pay to PECO the Unpaid  Balance  on  the
     Loan  plus  accumulated interest or, (ii) cause RENTAL  to  sell  such
     number  of  the Gen Sets as are required to pay the Unpaid Balance  to
     PECO  and any remaining obligations to the Primary Lenders, and, (iii)
     grant a security interest to PECO in the GEN SETS such that if O'BRIEN
     fails  to  pay  the  full amount of the Unpaid Balance  by  the  Final
     Repayment Date, subject to any regulatory

<PAGE>

                                  O'BRIEN
                               ENVIRONMENTAL
                                  ENERGY
                               [Letterhead]

Mr. William L. Bardeen
July 21, 1994
Page 5

     approvals  that  PECO deems necessary, O'BRIEN shall be  obligated  to
     cause  RENTAL to assign RENTAL's full interest in all of the Gen  Sets
     to  PECO.   The  Security Agreement shall also  provide,  and  O'BRIEN
     hereby  promises,  that PECO shall be entitled to  recover  any  costs
     reasonably  incurred by PECO or PECO's agent to sell the Gen  Sets  to
     satisfy  the  Loan  from the net proceeds of any  such  sale  and  any
     balance  remaining shall be returned to O'BRIEN.  At the time O'BRIEN,
     RENTAL, and PECO enter into the Security Agreement, O'BRIEN and RENTAL
     shall  execute whatever financing statements and other documents  that
     PECO,  in its sole judgment, deems necessary to enable PECO to perfect
     the security interest that the Security Agreement grants to PECO.

13.  Should PECO, in its sole judgment, deem it necessary to obtain
     approval, from the Federal Trade Commission, the Federal Energy
     Regulatory Commission, Pennsylvania Public Utility Commission, or any
     other agency or governmental entity, to undertake any of the actions
     required by this Letter Agreement, O'BRIEN will undertake all actions
     that, in PECO's sole judgment, are necessary, including making all
     complementary or concurrent filings that may be required.  PECO shall
     not be required to undertake or fulfill any obligation imposed by this
     Letter Agreement should an agency or other governmental entity
     disapprove of or forbid PECo from fulfilling the obligation.

14.  O'BRIEN will manage and lead negotiations with the PWD, PIVIA, and, as
     appropriate,   other   City   of  Philadelphia   officials,   on   the
     restructuring  and  amendment of the ESAs and shall  consult  PECO  on
     strategy.  PECO shall cooperate with O'BRIEN and shall attend meetings
     with  O'BRIEN  and City officials in support of O'BRIEN's negotiations
     consistent with the strategy.  PECO shall not separately negotiate  or
     maintain  contact with the City or any other party involved  with  the
     ESAs, including OPCAI, Woodforde Energy, Inc., Mrs. Marsha Perelman or
     any  of her affiliates or representatives, regarding any amendment  of
     the  ESAs or the provision of service under the EER contracts,  except
     with  the  prior  written  approval of O'BRIEN.   Except  for  initial
     telephone contacts to establish meeting dates and times, O'BRIEN shall
     not  separately  discuss  with the PWID,  the  PIVIA,  or  other  City
     officials,  the EER contract provisions PECO has agreed to  herein  or
     the details of the EER contracts as the negotiations proceed.

15.  Upon  the  execution of the amended ESAs, the Transfer Agreement,  and
     the  EER  contracts  contemplated herein, PECO will  pay  O'BRIEN  the
     difference  between  $9.5  million and the  then  remaining  principal
     amount  and  any accrued interest of the Loan owed to PECO by  O'BRIEN
     and shall provide O'BRIEN with written certification that the Loan has
     been satisfied in full.

16.  O'BRIEN  represents  to  PECO  that as of  the  date  of  this  Letter
     Agreement,  it  knows  of  no outstanding  claims  against  OPCI,  and
     promises  that, with respect to any claims that may be  made  or  that
     accrue against OPCI between the date of this Letter Agreement and  the
     date of the execution of the amended ESAs, the Transfer Agreement, and
     the  EER  contracts, O'BRIEN and its affiliates shall fully  indemnify
     and hold PECO harmless from

<PAGE>

                                  O'BRIEN
                               ENVIRONMENTAL
                                  ENERGY
                               [Letterhead]

Mr. William L. Bardeen
July 21, 1994
Page 6

and against any losses or damages, including attorney's fees and expenses
incurred to defend against any such claims, that PECO might suffer as the
result of any such claims should PECO ever obtain title to the OPCI stock
as contemplated herein.

As with our original restructuring proposal and in accordance with our Non-
Disclosure  Agreement,  this  Letter  Agreement  is  hereby  designated  as
"Confidential" by O'BRIEN and may not be disclosed to any other  party  for
any purpose without O'BRIEN's or PECO's prior written permission.

By signing below, both parties intend to be legally bound by the foregoing.

Thank you for your consideration.

Sincerely,                              ACCEPTED AND AGREED TO BY:

/s/ Robert A. Shinn                     /S/ W. L. Bardeen
Robert A. Shinn                         W. L. Bardeen
Vice President                          for PECO Energy Company
O'BRIEN Environmental Energy, Inc.      DATE:  7/21/94


cc:
cc: P. T. Eastman
    F. L. O'BRIEN, III
   L. Zalkin
   J. Cooperman

<PAGE>

                    Schedule 1
               Loan Amortization

Amount                     $5,500,000
Interest Rate/year               0.12
Monthly Payment               116,000

a.       Unpaid
b.   Month Balance   Payment    Interest     Principal
1       5,500,000    116,000    55,000        61,000
2       5,439,000    116,000    54,390        61,610
3       5,377,390    116,000    53,774        62,226
4       5,315,164    116,000    53,152        62,848
5       5,252,316    116,000    52,523        63,477
6       5,188,839    116,000    51,888        64,112
7       5,124,727    116,000    51,247        64,753
8       5,059,974    116,000    50,600        65,400
9       4,994,574    116,000    49,946        66,054
10      4,928,520    116,000    49,285        66,715
11      4,861,805    116,000    48,618        67,382
12      4,794,423    116,000    47,944        68,056
13      4,726,367    116,000    47,264        68,736
14      4,657,631    116,000    46,576        69,424
15      4,588,207    116,000    45,882        70,118
16      4,518,089    116,000    45,181        70,819
17      4,447,270    116,000    44,473        71,527
18      4,375,743    116,000    43,757        72,243
19      4,303,500    116,000    43,03S        72,965
20      4,230,535    116,000    42,305        73,695
21      4,156,841    116,000    41,568        74,432
22      4,082,409    116,000    40,824        75,176
23      4,007,233    116,000    40,072        75,928
24      3,931,306    116,000    39,313        76,687
25      3,854,619    116,000    38,546        77,454
26      3,777,165    116,000    37,772        78,228
27      3,698,936    116,000    36,989        79,011
28      3,619,926    116,000    36,199        79,801
29      3,540,125    116,000    35,401        80,599
30      3,459,526    116,000    34,595        81,405
31      3,378,122    116,000    33,781        82,219
32      3,295,903    116,000    32,959        83,041
33      3,212,862    116,000    32,129        83,871
34      3,128,990    116,000    31,290        84,710
35      3,044,280    116,000    30,443        85,557
36      2,958,723    116,000    29,587        86,413

<PAGE>

Schedule 1, Loan Amortization
Page 2

37      2,872,310    116,000    28,723        87,277
38      2,785,034    116,000    27,850        88,150
39      2,696,884    116,000    26,969        89,031
40      2,607,853    116,000    26,079        89,921
41      2,517,931    116,000    25,179        90,821
42      2,427,111    116,000    24,271        91,729
43      2,335,382    116,000    23,354        92,646
44      2,242,735    116,000    22,427        93,573
45      2,149,163    116,000    21,492        94,508
46      2,054,654    116,000    20,547        95,453
47      1,959,201    116,000    19,592        96,408
48      1,862,793    116,000    18,628        97,372
49      1,765,421    116,000    17,654        98,346
50      1,667,075    116,000    16,671        99,329
51      1,567,746    116,000    15,677       100,323
52      1,467,423    116,000    14,674       101,326
53      1,366,098    116,000    13,661       102,339
54      1,263,759    116,000    12,638       103,362
55      1,160,396    116,000    11,604       104,396
56      1,056,000    116,000    10,560       105,440
57        950,560    116,000     9,506       106,494
58        844,066    116,000     8,441       107,559
59        736,506    116,000     7,365       108,635
60        627,871    116,000     6,279       109,721
61        518,150    116,000     5,182       110,818
62        407,332    116,000     4,073       111,927
63        295,405    116,000     2,954       113,046
64        182,359    116,000     1,824       114,176
65         68,183    116,000       682        68,183


Unadjusted Term: 5.42 Years

NOTE:

Commencing September 20, 1994, and on the 20th day of each succeeding month
during  the  term  of the Loan, O'Brien will revise this  Schedule  1  Loan
Amortization Table in accordance with section 1 of the Letter Agreement and
the  provisions  of  Schedule 2 and forward the revised amortization  table
(the  "Revised Schedule 1") to PECO for approval, such approval not  to  be
unreasonably  withheld.   The Monthly PECO Loan Payment  of  $116,000  will
remain  a  constant  in the Revised Schedule 1, while the  remaining  Term,
Unpaid Balance, Interest, and Principal payments in the revised Schedule  1
will be subject to adjustment.

The following examples illustrate how the original and revised versions of
Schedule 1 would be subject to change:

A.   If, based on Schedule 2, only $100,000 of the first month's payment is
     paid on time, then the Unpaid Balance for the second month will be
     increased by $16,000 to $5,455,000 and the Interest due for the second
     month will be $54,550.

B.   If no payment is made in the first month, then the balance due for the
     second  month will be $5,555,000 and the interest due for  the  second
     month will be $55,550.

C.   If,  based  on Schedule 2, $130,000 is available and paid to  PECO  as
     payment  in  the first month, then the Unpaid Balance for  the  second
     month  will  be adjusted to $5,425,000 and the interest  due  for  the
     second month will be $54,250.

<PAGE>

(a)  Schedule 2

(b)  Order of Monthly Distribution Payments


1.   Primary Gen Set Lenders' Lease Payments.
2.   An  amount equal to O'BRIEN's Lease Margin as defined below  plus  the
     Operation  & Maintenance Reimbursement of $25,000, such amount  to  be
     escalated each year by four (4) percent, to PECO Energy.
3.   If  applicable,  the estimated Preferred Stockholder Dividend  to  the
     OPCI dividend reserve account.
4.   The monthly PECO Loan Payment amount less the amount in line 2 above.
5.   Operation  & Maintenance Reimbursement of $25,000, such amount  to  be
     escalated each year by four (4) percent, to O'BRIEN.
6.   Any remaining amount to PECO to further reduce the remaining principal
     amount of the loan.

For purposes of this Schedule 2, O'BRIEN's Lease Margin, means $195,761 per
month less the Primary Gen Set Lenders' Lease Payments.

<PAGE>

SCHEDULE 2 ADDENDUM
LOCKBOX ARRANGEMENTS
OPCI SERVICE FEES AND DISTRIBUTIONS

As  provided in section one of the Letter Agreement, upon the making of the
Loan  O'BRIEN will establish a Lockbox Account (the "Lockbox") with a  bank
(the  "Bank"), acceptable to PECO and paid for by O'BRIEN, to  receive  and
distribute OPCI service fees.  The Bank will have standing instructions  to
follow  the  following procedures each month with respect to  the  flow  of
funds;

1.   Monthly  service  fee  checks  will be remitted  by  the  Philadelphia
     Municipal Authority ("PMA') directly to the Bank in the name of  OPCI.
     These  checks are typically received between the 10th and 12th day  of
     each month.

2.   As  with PECO's own billing and payment schedule, there is a time  lag
     (approximately 45 days) between the end of the applicable PECO billing
     period and the date the OPCI service fees are paid.  While O'BRIEN, as
     the  new  holder  of  OPCI common stock, will be  entitled  to  accrue
     dividends  commencing  August  6,  1994  (the  day  after  the   Stock
     Repurchase), the actual disbursement of the common stock dividend  for
     the  period  August 6 through August 22, 1994 will  not  be  available
     until October 12, 1994, and the common stock dividend accrued for  the
     period  August  22  through September 22, 1994 will not  be  available
     until November 12, 1994.

2.   PECO, RENTAL and O'BRIEN will maintain a demand deposit account at the
     Bank during the term of the Loan.

3.   On  the  12th  of  each month, the Bank will automatically  debit  the
     account  of  OPCI and distribute payments in the amounts  and  in  the
     order  of the distribution categories shown in Schedule 2.  Since  the
     Preferred  Stockholder Dividend (category number 4 on Schedule  2)  is
     payable quarterly, if applicable and if funds are available, the  Bank
     will  debit  the  account of OPCI monthly in an  amount  estimated  by
     O'BRIEN  to  be  the then current month's share of  the  then  current
     quarter's  projected preferred stock dividend and deposit such  amount
     into a separate dividend reserve account to be established at the Bank
     and  controlled by OPCI.  If applicable, the preferred stock  dividend
     will  be  calculated  in accordance with the formula  described  in  a
     letter  from O'BRIEN to OPCAI dated November 12, 1993 attached  hereto
     as Schedule 3.

4.   OPCI will be entitled to maintain a minimum monthly working capital,
     balance of $5,000 at all times during the term of the Loan.