SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549
              ----------------------------------------------------

                                    FORM 10-K

(mark one)
[ X ] Annual Report Pursuant to Section 13 or 15(d) of the Securities
      Exchange Act of 1934 for the fiscal year ended April 3, 1999

[   ] Transition Report Pursuant to Section 13 or 15(d) of the Securities
      Exchange Act of 1934

                          Commission file number 1-9549

                              THERMO TERRATECH INC.
             (Exact name of Registrant as specified in its charter)

Delaware                                                        04-2925807
(State or other jurisdiction of       (I.R.S. Employer Identification No.)
 incorporation or organization)

81 Wyman Street, P.O. Box 9046
Waltham, Massachusetts                                           02454-9046
(Address of principal executive offices)                         (Zip Code)

       Registrant's telephone number, including area code: (781) 622-1000

           Securities registered pursuant to Section 12(b) of the Act:

    Title of each class               Name of each exchange on which registered
 Common Stock, $.10 par value                  American Stock Exchange

           Securities registered pursuant to Section 12(g) of the Act:
                                      None

Indicate by check mark whether the Registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the preceding 12 months and (2) has been subject to the filing requirements for
at least the past 90 days. Yes [ X ] No [ ]

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405
of Regulation S-K is not contained herein, and will not be contained, to the
best of the Registrant's knowledge, in definitive proxy or information
statements incorporated by reference into Part III of this Form 10-K or any
amendment to this Form 10-K. [ ]

The aggregate market value of the voting stock held by nonaffiliates of the
Registrant as of April 30, 1999, was approximately $9,493,000.

As of April 30, 1999, the Registrant had 19,049,354 shares of Common Stock
outstanding.

                       DOCUMENTS INCORPORATED BY REFERENCE

Portions of the Registrant's Fiscal 1999 Annual Report to Shareholders for the
year ended April 3, 1999, are incorporated by reference into Parts I and II.

Portions of the Registrant's definitive Proxy Statement for the Annual Meeting
of Shareholders to be held on September 16, 1999, are incorporated by reference
into Part III.

<PAGE>


                                     PART I

Item 1.  Business

(a)   General Development of Business

     Thermo TerraTech Inc. (the Company or the Registrant)  provides  industrial
outsourcing services and manufacturing support encompassing a broad range of
specializations. The Company operates in four segments: environmental-liability
management, engineering and design, laboratory testing, and metal treating.

      The Environmental-liability Management segment includes the Company's
majority-owned, publicly held ThermoRetec Corporation (formerly Thermo
Remediation Inc.) subsidiary, which is a national provider of
environmental-liability and resource-management services. Through a nationwide
network of offices, ThermoRetec offers these and related consulting services in
four areas: consulting and engineering, nuclear remediation, soil remediation,
and fluids recycling. As of April 3, 1999, the Company owns 70% of ThermoRetec's
outstanding common stock and holds a $2.7 million principal amount 3 7/8%
subordinated convertible note due 2000 issued by ThermoRetec, convertible into
shares of ThermoRetec common stock at a conversion price of $9.83 per share. The
Company's majority-owned Thermo EuroTech N.V. subsidiary, located in the
Netherlands, specializes in converting "off-spec" and contaminated petroleum
fluids into useable oil products. Thermo EuroTech also provides in-plant waste
management and recycling services through its Ireland-based Green Sunrise
Holdings Ltd. subsidiary. As of April 3, 1999, the Company owns 78% of Thermo
EuroTech's outstanding common stock.

      The Engineering and Design segment includes the Company's majority-owned,
publicly held The Randers Killam Group Inc. (formerly The Randers Group
Incorporated) subsidiary, which provides comprehensive engineering and
outsourcing services in four areas: water and wastewater treatment, process
engineering and construction, highway and bridge engineering, and infrastructure
engineering. As of April 3, 1999, the Company owns approximately 95% of Randers
Killam's outstanding common stock. This segment also includes the Company's
wholly owned Normandeau Associates Inc. subsidiary, which provides consulting
services that address natural resource management issues.

      The Company's wholly owned Thermo Analytical Inc. subsidiary, which
represents the Laboratory Testing segment, operates analytical laboratories that
provide environmental- and pharmaceutical-testing services, primarily to
commercial clients throughout the U.S.

      The Metal Treating segment performs metallurgical processing services
using thermal-treatment equipment at locations in California, Minnesota, and
Wisconsin.

      In May 1999, the Company announced the planned sale of several businesses
by its majority-owned subsidiaries. In connection with these proposed sales, the
Company expects to incur pretax charges totaling approximately $65 million,
primarily in the first quarter of fiscal 2000. Thermo EuroTech intends to sell
its used-oil processing operations, Randers Killam plans to sell three operating
units, and ThermoRetec plans to sell three soil-recycling facilities. For the
fiscal year ended April 3, 1999, revenues and operating loss from these
businesses totaled approximately $50 million and $0.1 million, respectively.

      The Company was incorporated on May 30, 1986, as an indirect, wholly owned
subsidiary of Thermo Electron Corporation. As of April 3, 1999, Thermo Electron
owned 16,605,831 shares of the Company's common stock, representing 87% of such
stock outstanding. Thermo Electron is a world leader in monitoring, analytical,
and biomedical instrumentation; biomedical products including heart-assist
devices, respiratory-care equipment, and mammography systems; and paper
recycling and papermaking equipment. Thermo Electron also develops
alternative-energy systems and clean fuels, provides a range of services
including industrial outsourcing and environmental-liability management, and
conducts research and development in advanced imaging, laser, and electronic
information-management technologies.


                                       2
<PAGE>

      Thermo Electron has from time to time repurchased shares of the Company's,
ThermoRetec's, Randers Killam's, and Thermo EuroTech's common stock in the open
market or in negotiated transactions. During fiscal 1999*, Thermo Electron
purchased 670,521 shares, 70,800 shares, and 474,000 shares of the Company's,
ThermoRetec's, and Thermo EuroTech's common stock, respectively, in the open
market and negotiated transactions for a total price of $3.4 million, $0.2
million, and $1.5 million, respectively.

      Thermo Electron has announced a proposed reorganization involving certain
of Thermo Electron's subsidiaries, including the Company. Under this plan, the
Company, ThermoRetec, and Randers Killam would be merged into Thermo Electron.
As a result, all three companies would become wholly owned subsidiaries of
Thermo Electron. The public shareholders of the Company, ThermoRetec, and
Randers Killam would receive common stock in Thermo Electron in exchange for
their shares. The completion of these transactions is subject to numerous
conditions, as outlined in Note 17 to Consolidated Financial Statements in the
Registrant's Fiscal 1999 Annual Report to Shareholders, which statements are
incorporated herein by reference.

Forward-looking Statements

      Forward-looking statements, within the meaning of Section 21E of the
Securities Exchange Act of 1934, are made throughout this Annual Report on Form
10-K. For this purpose, any statements contained herein that are not statements
of historical fact may be deemed to be forward-looking statements. Without
limiting the foregoing, the words "believes," "anticipates," "plans," "expects,"
"seeks," "estimates," and similar expressions are intended to identify
forward-looking statements. There are a number of important factors that could
cause the results of the Company to differ materially from those indicated by
such forward-looking statements, including those detailed under the heading
"Forward-looking Statements" in the Registrant's Fiscal 1999 Annual Report to
Shareholders, which statements are incorporated herein by reference.

(b)   Financial Information About Segments

      Financial information concerning the Company's segments is summarized in
Note 15 to Consolidated Financial Statements in the Registrant's Fiscal 1999
Annual Report to Shareholders, which information is incorporated herein by
reference.

(c)   Description of Business

      (i)  Principal Services and Products

Environmental-liability Management

      The Company provides environmental consulting and remediation construction
management to clients in the transportation, refining, chemical, wood-treating,
gas, and electric utility industries across the nation. The Company offers a
broad array of remedial solutions to help clients manage problems associated
with environmental compliance, resource management, and the remediation of
industrial sites contaminated with various wastes and residues. The Company
provides particular expertise in bioremediation and in managing wastes from
manufactured-gas plants, refineries, and railroad properties.

      The Company also performs cleanups of hazardous waste sites for government
and industry as a prime construction contractor and completes predesigned
remedial action contracts at sites containing hazardous, toxic, and radioactive
wastes. Under contracts with federal and state governments, and other public and
private sector clients, the Company also provides project management and
construction services for the remediation of hazardous and nonhazardous wastes.
Most of this contract work is obtained through a bid process, with the job being
awarded to the best qualified bidder.

--------------------
*  References to fiscal 1999, 1998, and 1997 herein are for the fiscal years
   ended April 3, 1999, April 4, 1998, and March 29, 1997, respectively.


                                       3
<PAGE>

      In addition, the Company helps public utilities, government institutions,
and Fortune 500 companies develop and implement management and computer-based
systems that aid in the collection and application of environmental and
resource-management data. By helping to establish or improve a customer's
environmental-compliance program, the Company's customized services promote and
support the integration of environmental-management functions with everyday
business activities. The Company's services help multinational companies
accurately estimate and control the cost of their environmental-compliance and
health and safety efforts. The Company also develops measurement systems that
track clients' progress toward their stated environmental performance goals.

      The Company provides services to remove radioactive contaminants from
sand, gravel, and soil, as well as health physics services, radiochemistry
laboratory services, radiation dosimetry services, radiation-instrument
calibration and repair services, and radiation-source production. As part of its
radiation and nuclear/health physics services business, the Company provides
site surveys for radioactive materials and on-site samples, as well as analysis
in support of decontamination programs and dosimetry services to measure
personnel exposure. In addition, using its proprietary segmented-gate system
technology, the Company removes radioactive contaminants from sand, gravel, and
soil. A substantial part of the Company's health physics services has been
performed under the U.S. Department of Energy's remedial action programs.

      The Company designs and operates facilities for the remediation of
nonhazardous soil. The Company's soil-remediation centers are environmentally
secure facilities for receiving, storing, and processing petroleum-contaminated
soils. Each site consists principally of a soil-remediation unit and a
soil-storage area. The Company currently provides soil-remediation services at
facilities in California, Oregon, Washington, Maryland, and New York. During
fiscal 1999, the Company announced plans to close two soil-recycling facilities,
one of which was closed in March 1999. The Company is actively seeking a buyer
for the second facility. In May 1999, ThermoRetec announced plans to sell three
additional soil-recycling facilities.

      The market for remediation of petroleum-contaminated soils, as with many
other waste markets, was created by environmental regulations. The market for
soil-remediation services has been driven largely by state programs to enforce
the Environmental Protection Agency's (EPA's) underground storage tank (UST)
regulations and to fund cleanups. UST compliance requirements and attendant
remediation costs are often beyond the financial capabilities of individuals and
smaller companies. To address this problem, some states established
tax-supported trust funds to assist in the financing of UST compliance and
remediation. Many states have realized that the number of sites requiring
remediation and the costs of compliance are substantially higher than were
originally estimated. As a result, several states have significantly reduced
compliance requirements and altered regulatory approaches and standards in order
to reduce the costs of cleanup. More lenient regulatory standards, reduced
enforcement, and uncertainty with respect to such changes have already resulted
in lower levels of cleanup activity in most states where the Company conducts
business, which had a material adverse effect on the Company's business in
recent years. Although the Company expects this market to remain viable for some
time after April 3, 1999, there can be no assurance that this business will not
decline in future years.

      The Company offers a full spectrum of environmental services related to
managing and recycling nonhazardous, liquid, and solid materials generated by
business and industry. The Company's client base is largely public retail and
industrial businesses, but also includes municipalities, public utilities,
railroads, the mining industry, and government agencies. The materials managed
by the Company for its customers primarily are used oils and oil-contaminated
waters, which are continuously generated as part of the customers' operations.
As such, the Company provides services for its customers on a recurring basis.
The Company processes the materials it collects into products for resale and/or
recycling, such as fuel, glycol, steel, and clean water. The Company has
expanded its services to include a variety of field technical services,
including on-site waste sampling and testing, emergency response, and tank
cleaning.

                                       4
<PAGE>

      Thermo EuroTech specializes in processing "off-spec" mixtures of oil that
contain water, ash, and sediment into commercially tradable end products used in
blending. The end products of this process are commercial grade oils that can be
blended to make diesel fuels and marine fuels or be used as a feed material. In
recent years, the global drop in oil prices has affected sales of the off-spec
oil produced at Thermo EuroTech's North Refinery division. Because of the price
decline and instability in the worldwide oil market, Thermo EuroTech has applied
to Dutch authorities for licenses to broaden the variety of waste streams that
could be treated at North Refinery. In addition, Thermo EuroTech has taken steps
to replace and diversify its feedstock suppliers. However, no assurance can be
given that it will not experience future disruptions in deliveries. In May 1999,
the Company announced plans to exit this business. Thermo EuroTech also provides
in-plant waste management and recycling services through its Ireland-based Green
Sunrise subsidiary.

      During fiscal 1999, 1998, and 1997, the Company derived revenues of $159.1
million, $141.1 million, and $126.8 million, respectively, from
environmental-liability management services.

Engineering and Design

      The Company provides comprehensive engineering and outsourcing services in
such areas as water and wastewater treatment, process engineering and
construction, highway and bridge engineering, and infrastructure engineering. A
substantial portion of the Company's engineering and design services sales are
made to existing customers on a repeat basis. Engineering and design services
are often performed as multiyear studies. In addition to federal, state, and
local governments, customers include public utilities, waste management
companies, oil refineries, mining companies, chemical manufacturers,
architectural and engineering firms, and a variety of service companies involved
with real estate transactions.

      The Company specializes in the design, planning, and construction
observation of municipal and privately owned water treatment plants, wastewater
treatment plants, and hazardous wastewater facilities. The Company provides
full-service contract operations to plant owners in the public and private
sectors. These services facilitate regulatory compliance; optimize day-to-day
plant operations; reduce costs; provide competent, experienced personnel; and
promote good community relations.

      In addition, the Company provides design engineering, project management,
and construction services for industrial clients in the manufacturing,
pharmaceutical, and chemical-processing industries, principally in the Mid-West,
Massachusetts, and West Virginia; a broad range of consulting services that
address transportation planning and design; and transportation and environmental
consulting, professional engineering, and architectural services.

      In May 1999, Randers Killam announced plans to sell three businesses: the
Randers division, which provides the Company's process engineering and
construction services; BAC Killam Inc., which provides the Company's highway and
bridge engineering services; and E3-Killam Inc., which provides a small portion
of the Company's water and wastewater treatment services.

      During fiscal 1999, 1998, and 1997, the Company derived revenues of $91.8
million, $84.6 million, and $74.8 million, respectively, from engineering and
design services.

Laboratory Testing

      The Company provides comprehensive laboratory-based services for the
environmental and pharmaceutical industries. Analytical laboratory services
consist of a comprehensive range of analytical tests to detect and measure
organic contaminants and inorganic contaminants in samples of soil, water, air,
industrial wastes, and biological materials. The Company also provides testing
services for major pharmaceutical companies in support of their new healthcare
drug development.

      During fiscal 1999, 1998, and 1997, the Company derived revenues of $40.5
million, $37.5 million, and $35.4 million, respectively, from laboratory testing
services.



                                       5
<PAGE>

Metal Treating

      The Company performs metallurgical processing services using
thermal-treatment equipment at locations in California, Minnesota, and
Wisconsin. Through its Holcroft Division, which was sold in October 1997, the
Company designed, manufactured, and installed computer-controlled,
custom-engineered, thermal-processing systems used to treat primary metals and
metal parts.

      During fiscal 1999, 1998, and 1997, the Company derived revenues of $19.3
million, $36.6 million, and $44.3 million, respectively, from metal treating
services and process systems.

      (ii) New Products

      The Company has made no commitments to new products that would require the
investment of a material amount of the Company's assets.

      (iii) Raw Materials

      Prior to fiscal 1996, a large percentage of oil feedstock at Thermo
EuroTech's North Refinery division came from the former Soviet Union. Thermo
EuroTech no longer receives any oil from that nation as a result of political
and economic changes that make transportation of waste oil difficult. To
overcome this loss of supply, Thermo EuroTech has taken steps to replace and
diversify its feedstock suppliers. However, no assurance can be given that it
will not experience future disruptions in deliveries. In May 1999, the Company
announced plans to sell the North Refinery division.

      Since the Company's business is primarily service oriented, it does not
involve the processing of raw materials and is not dependent on fluctuations in
the supply or price of raw materials, except as described above. To date, the
Company has not experienced any difficulty in obtaining any of the materials or
components used in its operations and does not foresee any such difficulty in
the future. The Company has multiple sources for all of its significant raw
material needs.

      (iv) Patents, Licenses, and Trademarks

      The Company currently owns or has rights under licenses to a number of
U.S. patents. Although the Company believes that patent protection provides it
with competitive advantages with respect to certain portions of its business and
will continue to seek patent protection when appropriate, the Company also
believes that its business depends primarily upon trade secrets and the
technical and marketing expertise of its personnel.

      (v)  Seasonal Influences

      A majority of the Company's businesses experience seasonal fluctuations. A
majority of the Company's soil-remediation sites, as well as the Company's
fluids-recycling sites, experience declines in revenues if severe weather
conditions occur. Site remediation work and certain environmental testing
services may decline in winter months as a result of severe weather conditions.
In Europe, Thermo EuroTech may experience a decline in the feedstock delivered
to and from its facilities during winter months due to frozen waterways.

      (vi) Working Capital Requirements

      In general, there are no special inventory requirements or credit terms
extended to customers that would have a material adverse effect on the Company's
working capital.

                                       6
<PAGE>


      (vii)  Dependency on a Single Customer

      See Government Contracts.

      (viii) Backlog
<TABLE>
<CAPTION>

      The Company's backlog of firm orders at fiscal year-end 1999 and 1998 was:

(In thousands)                                                                             1999      1998
-------------------------------------------------------------------------------------- --------- ---------

<S>                                                                                    <C>       <C>
Environmental-liability Management                                                     $ 47,635  $ 51,860

Engineering and Design                                                                   62,136    59,633

Laboratory Testing                                                                        2,517     2,362

Metal Treating                                                                              300       300
                                                                                       --------  --------
                                                                                       $112,588  $114,155
                                                                                       ========  ========

      These amounts include the backlog of all of the Company's subsidiaries,
with the exception of soil-recycling, fluids-recycling, and in-plant waste
management and recycling services, which are provided on a current basis
pursuant to purchase orders. Included in the Company's backlog at fiscal
year-end 1999 and 1998 is the incomplete portion of contracts that are accounted
for using the percentage-of-completion method. The Company believes that
substantially all of the backlog at April 3, 1999, will be completed during
fiscal 2000. Certain of these orders are subject to cancellation by the customer
upon payment of a cancellation charge and all government contracts are subject
to termination at any time by the government without penalty.

      (ix) Government Contracts

      Approximately 6%, 4%, and 13%, of the Company's revenues in fiscal 1999,
1998, and 1997, respectively, were derived from contracts or subcontracts with
the federal government that are subject to renegotiation of profits or
termination. The Company does not have any knowledge of threatened or pending
renegotiation or termination of any material contract or subcontract.

      (x)  Competition

      Many of the Company's businesses are engaged in highly competitive,
regional markets, with competition coming from numerous small firms offering
limited services, as well as much larger firms that offer an array of services.

Environmental-liability Management

      In the market for consulting and engineering services, the Company
competes with numerous regional and local companies as well as a number of
national remediation contractors. The Company competes primarily on the basis of
value, with the vast majority of the contracts it seeks awarded on the basis of
scope, effectiveness, and cost. Other competitive factors for the Company's
consulting and engineering businesses include: reputation; experience; breadth
and quality of services offered; and technical, managerial, and business
proficiency.

      The type of radiation and nuclear/health physics services offered by the
Company are also offered by many large national companies. The Company competes
primarily on the basis of its proprietary technology and price.

      Competition in the soil-remediation business is intense. The Company's
principal competitors are landfills, including major landfill companies. The
Company also currently competes with companies offering a wide range of disposal
options, including other fixed-site, thermal-treatment facilities, operators of
mobile thermal-treatment facilities, bioremediation and vapor-extraction
facilities, and, in certain states, with asphalt plants and brick kilns that

                                       7
<PAGE>

use the contaminated soil in their production processes. Competition in the
soil-remediation market has always been highly localized, consisting mostly of
single-site or single-unit operators. Competitive conditions limit the prices
charged by the Company in each local market for soil-remediation services.
Pricing is therefore a major competitive factor for the Company. The Company
believes competition and price pressure will remain intense for the foreseeable
future.

      Competition in the fluids recycling market is highly fragmented and ranges
in size from small, under-capitalized private enterprises to larger national
public companies. At both ends of this spectrum, the industry continues to
consolidate and restructure. The Company competes primarily on the basis of
quality and price.

      Thermo EuroTech faces competition for oil from other oil processors and
blenders and from a company with a similar distillation technology in Italy. The
market for blending oils is very large and oils such as Thermo EuroTech's end
products represent a very small percentage of the total market. Green Sunrise is
the leading integrated service provider in an emerging, still fragmented market.
No one competitor offers Green Sunrise's complete line of services and no single
firm is dominant in any of Green Sunrise's primary service areas. Thermo
EuroTech competes primarily on the basis of price.

Engineering and Design

      The Company's engineering and design businesses are engaged in highly
competitive markets in all of its service areas. These markets tend to be
regional. In its geographic service area, competition consists of small, one- to
three-person firms offering a limited scope of services, as well as much larger
firms that may be regional, national, or international in the scope of services
they offer. The principal competitive factors for the Company are: reputation;
experience; price; breadth and quality of services offered; and technical,
managerial, and business proficiency.

Laboratory Testing

      Hundreds of independent analytical testing laboratories and consulting
firms compete for business nationwide. Many of these firms use equipment and
processes similar to those of the Company. Competition is based not only on
price, but also on reputation for accuracy, quality, and the ability to respond
rapidly to customer requirements. In addition, many industrial companies have
their own in-house analytical testing capabilities. The Company believes that
its competitive strength lies in the quality of its services.

Metal Treating

      The market for metal-treating services is typically regional and
competitive. All regions in which the Company has facilities contain numerous
competitors. In addition, in-house heat-treating facilities provide a major
source of competition. The Company competes in this segment on the basis of
services provided, turnaround time, and price.

      (xi) Environmental Protection Regulations

      The Company believes that compliance by the Company with federal, state,
and local environmental protection regulations will not have a material adverse
effect on its capital expenditures, earnings, or competitive position.

      (xii) Number of Employees

      As of April 3, 1999, the Company employed approximately 2,900 persons.

(d)   Financial Information About Geographic Areas

      The Company's sales in foreign locations are currently insignificant.
</TABLE>

                                       8
<PAGE>


(e)   Executive Officers of the Registrant
<TABLE>
<CAPTION>
<S>                                 <C>     <C>

        Name                          Age   Present Title (Fiscal Year First Became Executive
                                            Officer)
        ---------------------------- ------ -----------------------------------------------------

        Dr. John P. Appleton          64    President and Chief Executive Officer (1993)
        Emil C. Herkert               61    Vice President (1996)
        Jeffrey L. Powell             40    Vice President (1994)
        Theo Melas-Kyriazi            39    Chief Financial Officer (1999)
        Paul F. Kelleher              56    Chief Accounting Officer (1986)

      Each executive officer serves until his successor is chosen or appointed
by the Board of Directors and qualified or until earlier resignation, death, or
removal. All executive officers, except Mr. Herkert and Mr. Powell, have held
comparable positions for at least five years, either with the Company or with
its parent company, Thermo Electron. Mr. Herkert has served as President of
Killam Associates, a subsidiary of Randers Killam, since 1977 and was appointed
Chief Executive Officer of Randers Killam in May 1997. Mr. Powell served as
President of ThermoRetec since its inception in 1993, and as its Chief Executive
Officer from May 1997 until April 1998, when he was named Senior Vice President.
Mr. Melas-Kyriazi was appointed Chief Financial Officer of the Company and
Thermo Electron on January 1, 1999. He joined Thermo Electron in 1986 as
Assistant Treasurer, and became Treasurer in 1988. He was named President and
Chief Executive Officer of ThermoSpectra Corporation, a public subsidiary of
Thermo Instrument Systems Inc., in 1994, a position he held until becoming Vice
President of Corporate Strategy for Thermo Electron in 1998. Mr. Melas-Kyriazi
remains a Vice President of Thermo Electron. Messrs. Melas-Kyriazi and Kelleher
are full-time employees of Thermo Electron, but devote such time to the affairs
of the Company as the Company's needs reasonably require.

Item 2.  Properties

      The location and general character of the Company's principal properties
by segment as of April 3, 1999, are:

Environmental-liability Management

      The Company owns approximately 115,000 square feet of office, engineering,
laboratory, and production space, principally in Ireland, the Netherlands, and
California, and leases approximately 200,000 square feet of office, engineering,
laboratory, and production space pursuant to leases expiring in fiscal 2000
through 2023, principally in Ireland, Colorado, Pennsylvania, Massachusetts, and
New Mexico.

      The Company also owns approximately 72 acres in Maryland, California,
Oregon, and Idaho, from which it provides soil-remediation services. The Company
occupies approximately 20 acres principally in New York, Washington, and South
Carolina pursuant to leases expiring in fiscal 2000 through 2006, from which it
provides soil-remediation services.

      The Company leases approximately six acres on one site in Arizona and one
site in Nevada pursuant to leases expiring in fiscal 2001 and 2003,
respectively, upon which it has constructed fluids storage and processing
equipment.

      The Company occupies approximately 15 acres in Delfzijl, the Netherlands,
pursuant to a lease expiring in 2059, consisting of office space, distillation
facilities, and oil storage tanks.

Engineering and Design

      The Company owns approximately 75,000 square feet of office, engineering,
and laboratory space in New Jersey, Massachusetts, and Michigan, and leases
approximately 180,000 square feet of office, engineering, and laboratory space
pursuant to leases expiring in fiscal 2000 through 2008, principally in
Pennsylvania, New Jersey, New York, Florida, New Hampshire, and Michigan.

                                       9
<PAGE>

Laboratory Testing

      The Company owns approximately 180,000 square feet of office and
laboratory space in Pennsylvania, and leases approximately 12,000 square feet of
office and laboratory space pursuant to leases expiring in fiscal 2001 and 2009
in Michigan and South Carolina, respectively.

Metal Treating

      The Company owns approximately 140,000 square feet of office, laboratory,
and production space in Minnesota and Wisconsin, and leases approximately
330,000 square feet of office, laboratory, and production space pursuant to
leases expiring in fiscal 2003 in California.

      The Company believes that these facilities are in good condition and are
adequate for its present operations and that other suitable space is readily
available if any of such leases are not extended. With respect to leases
expiring in the near future, in the event the Company does not renew such
leases, the Company believes suitable alternate space is available for lease on
acceptable terms.

Item 3.  Legal Proceedings

      Not applicable.

Item 4.  Submission of Matters to a Vote of Security Holders

      Not applicable.


                                       10
<PAGE>

                                     PART II
Item 5.  Market for Registrant's Common Equity and Related Stockholder Matters

      Information concerning the market and market price for the Registrant's
Common Stock, $.10 par value, and dividend policy are included under the
sections labeled "Common Stock Market Information" and "Dividend Policy" in the
Registrant's Fiscal 1999 Annual Report to Shareholders and is incorporated
herein by reference.

Item 6.  Selected Financial Data

      The information required under this item is included under the sections
labeled "Selected Financial Information" and "Dividend Policy" in the
Registrant's Fiscal 1999 Annual Report to Shareholders and is incorporated
herein by reference.

Item 7.  Management's Discussion and Analysis of Financial Condition and Results of Operations

      The information required under this item is included under the heading
"Management's Discussion and Analysis of Financial Condition and Results of
Operations" in the Registrant's Fiscal 1999 Annual Report to Shareholders and is
incorporated herein by reference.

Item 7A. Quantitative and Qualitative Disclosures About Market Risk

      The information required under this item is included under the heading
"Management's Discussion and Analysis of Financial Condition and Results of
Operations" in the Registrant's Fiscal 1999 Annual Report to Shareholders and is
incorporated herein by reference.

Item 8.  Financial Statements and Supplementary Data

      The Registrant's Consolidated Financial Statements as of April 3, 1999,
are included in the Registrant's Fiscal 1999 Annual Report to Shareholders and
are incorporated herein by reference.

Item 9.  Changes in and Disagreements with Accountants on Accounting and Financial Disclosure

      Not applicable.


                                       11
<PAGE>

                                    PART III
Item 10. Directors and Executive Officers of the Registrant

      The information concerning Directors required under this item is
incorporated herein by reference from the material contained under the caption
"Election of Directors" in the Registrant's definitive proxy statement to be
filed with the Securities and Exchange Commission pursuant to Regulation 14A,
not later than 120 days after the close of the fiscal year. The information
concerning delinquent filers pursuant to Item 405 of Regulation S-K is
incorporated herein by reference from the material contained under the heading
"Section 16(a) Beneficial Ownership Reporting Compliance" under the caption
"Stock Ownership" in the Registrant's definitive proxy statement to be filed
with the Securities and Exchange Commission pursuant to Regulation 14A, not
later than 120 days after the close of the fiscal year.

Item 11. Executive Compensation

      The information required under this item is incorporated herein by
reference from the material contained under the caption "Executive Compensation"
in the Registrant's definitive proxy statement to be filed with the Securities
and Exchange Commission pursuant to Regulation 14A, not later than 120 days
after the close of the fiscal year.

Item 12. Security Ownership of Certain Beneficial Owners and Management

      The information required under this item is incorporated herein by
reference from the material contained under the caption "Stock Ownership" in the
Registrant's definitive proxy statement to be filed with the Securities and
Exchange Commission pursuant to Regulation 14A, not later than 120 days after
the close of the fiscal year.

Item 13. Certain Relationships and Related Transactions

      The information required under this item is incorporated herein by
reference from the material contained under the caption "Relationship with
Affiliates" in the Registrant's definitive proxy statement to be filed with the
Securities and Exchange Commission pursuant to Regulation 14A, not later than
120 days after the close of the fiscal year.


                                       12
<PAGE>

                                     PART IV
Item 14. Exhibits, Financial Statement Schedules, and Reports on Form 8-K

(a,d) Financial Statements and Schedules

      (1)The consolidated financial statements set forth in the list below are
filed as part of this Report.

      (2)The consolidated financial statement schedule set forth in the list
below is filed as part of this Report.

      (3)Exhibits filed herewith or incorporated herein by reference are set
forth in Item 14(c) below.

      List of Financial Statements and Schedules Referenced in this Item 14

      Information incorporated by reference from Exhibit 13 filed herewith:

         Consolidated Statement of Operations
         Consolidated Balance Sheet
         Consolidated Statement of Cash Flows
         Consolidated Statement of Comprehensive Income and Shareholders' Investment
         Notes to Consolidated Financial Statements
         Report of Independent Public Accountants

      Financial Statement Schedule filed herewith:

         Schedule II:  Valuation and Qualifying Accounts

     All other schedules are omitted because they are not applicable or not
     required, or because the required information is shown either in the
     financial statements or the notes thereto.

(b)   Reports on Form 8-K

      None.

(c)   Exhibits

      See Exhibit Index on the page immediately preceding exhibits.
</TABLE>

                                       13
<PAGE>

                                   SIGNATURES
      Pursuant to the requirements of Section 13 or 15(d) of the Securities
Exchange Act of 1934, the Registrant has duly caused this report to be signed by
the undersigned, thereunto duly authorized.

Date:  June 10, 1999              THERMO TERRATECH INC.


                                  By: /s/ John P. Appleton
                                      John P. Appleton
                                      President and Chief Executive Officer

      Pursuant to the requirements of the Securities Exchange Act of 1934, this
report has been signed below by the following persons on behalf of the
Registrant and in the capacities indicated, as of June 10, 1999.

Signature                         Title


By:  /s/ John P. Appleton         President, Chief Executive Officer, and
     John P. Appleton              Director


By:  /s/ Theo Melas-Kyriazi       Chief Financial Officer
     Theo Melas-Kyriazi


By:  /s/ Paul F. Kelleher         Chief Accounting Officer
     Paul F. Kelleher


By:  /s/ John N. Hatsopoulos      Director
     John N. Hatsopoulos


By:  /s/ Brian D. Holt            Director
     Brian D. Holt


By:  /s/ Donald E. Noble          Director
     Donald E. Noble


By:  /s/ William A. Rainville     Director
     William A. Rainville


By:  /s/ Polyvios C. Vintiadis    Chairman of the Board and Director
     Polyvios C. Vintiadis

                                       14
<PAGE>


                    Report of Independent Public Accountants
To the Shareholders and Board of Directors of Thermo TerraTech Inc.:

      We have audited, in accordance with generally accepted auditing standards,
the consolidated financial statements included in Thermo TerraTech Inc.'s Annual
Report to Shareholders incorporated by reference in this Form 10-K, and have
issued our report thereon dated May 11, 1999 (except with respect to the matters
discussed in Note 19, as to which the date is June 1, 1999). Our audits were
made for the purpose of forming an opinion on those statements taken as a whole.
The schedule listed in Item 14 on page 13 is the responsibility of the Company's
management and is presented for purposes of complying with the Securities and
Exchange Commission's rules and is not part of the basic consolidated financial
statements. This schedule has been subjected to the auditing procedures applied
in the audits of the basic consolidated financial statements and, in our
opinion, fairly states in all material respects the consolidated financial data
required to be set forth therein in relation to the basic consolidated financial
statements taken as a whole.



                                                          Arthur Andersen LLP



Boston, Massachusetts
May 11, 1999

                                       15
<PAGE>
<TABLE>
<CAPTION>

SCHEDULE II

                              THERMO TERRATECH INC.
                        Valuation and Qualifying Accounts
                                 (In thousands)

<S>                                 <C>         <C>         <C>         <C>         <C>         <C>


                                    Balance at
                                     Beginning   Provision                Accounts                 Balance
                                            of  Charged to    Accounts     Written                  at End
Description                               Year     Expense   Recovered         Off   Other (a)     of Year
----------------------------------- ----------- ----------- ----------- ----------- ----------- -----------

 Allowance for Doubtful Accounts

Year Ended April 3, 1999               $ 4,450     $ 2,085     $   (45)    $(2,479)    $  (434)    $ 3,577

Year Ended April 4, 1998               $ 3,838     $ 1,141     $     -     $  (773)    $   244     $ 4,450

Year Ended March 29, 1997              $ 2,861     $   625     $    49     $  (516)    $   819     $ 3,838



 Description                                          Balance at     Provision          Cash       Balance
                                                       Beginning    Charged to      Payments        at End
                                                         of Year   Expense (c)                     of Year
--------------------------------------------------- ------------- ------------- ------------- -------------

Accrued Restructuring Costs (b)

Year Ended April 3, 1999                                  $    -       $ 2,095       $  (376)      $ 1,719


(a) Includes allowances of businesses acquired during the year as described in
    Note 3 to Consolidated Financial Statements in the Registrant's Fiscal 1999
    Annual Report to Shareholders. Fiscal 1999 amount includes an acquired
    company's reserves that were not required and were therefore reversed to
    cost in excess of net assets of acquired companies.
(b) The nature of activity in this account is described in Note 13 to
    Consolidated Financial Statements in the Registrant's Fiscal 1999 Annual
    Report to Shareholders.
(c) Excludes provision of $8.1 million for fixed asset and intangible asset
    write-downs.

                                       16
<PAGE>

                               EXHIBIT INDEX
Exhibit
Number     Description of Exhibit

  2.1      Purchase and Sale Agreement executed October 6, 1997, by and among
           Remediation Technologies, Inc., RETEC Thermal, Inc., TETRA Thermal,
           Inc., and TETRA Technologies, Inc. (filed as Exhibit 2.1 to Thermo
           Remediation Inc.'s Current Report on Form 8-K dated October 6, 1997
           [File No. 1-12636] and incorporated herein by reference).

  2.2      Assignment and Assumption Agreement executed October 6, 1997, by and
           among Remediation Technologies, Inc., RETEC Thermal, Inc., TETRA
           Thermal, Inc., and TETRA Technologies, Inc. (filed as Exhibit 2.2 to
           Thermo Remediation Inc.'s Current Report on Form 8-K dated October 6,
           1997 [File No. 1-12636] and incorporated herein by reference).

  2.3      Asset Purchase Agreement dated as of October 10, 1997, between the
           Registrant and Holcroft L.L.C. (filed as Exhibit 2.1 to the
           Registrant's Current Report on Form 8-K dated October 10, 1997 [File
           No. 1-9549] and incorporated herein by reference).

  2.4      $2,218,000.00 Principal Promissory Note issued by Holcroft L.L.C. to
           the Registrant (filed as Exhibit 2.2 to the Registrant's Current
           Report on Form 8-K dated October 10, 1997 [File No. 1-9549] and
           incorporated herein by reference).

  2.5      $663,117.82 Principal Promissory Note issued by Holcroft L.L.C. to
           the Registrant (filed as Exhibit 2.3 to the Registrant's Current
           Report on Form 8-K dated October 10, 1997 [File No. 1-9549] and
           incorporated herein by reference).

  2.6      Subordination Agreement dated as of October 10, 1997, between the
           Registrant and Comerica Bank (filed as Exhibit 2.4 to the
           Registrant's Current Report on Form 8-K dated October 10, 1997 [File
           No. 1-9549] and incorporated herein by reference).

  2.7      Stock Purchase and Sale Agreement dated May 12, 1997, by and between
           the Registrant and Thomas R. Eurich, Michael J. Krivitzky, Thomas J.
           McEnhill, and Bruce M. Bourdon (filed as Exhibit (iv) to Amendment
           No. 3 to Schedule 13D filed by Thermo Electron Corporation, Thermo
           Power Corporation, and the Registrant on May 13, 1997, and
           incorporated herein by reference).

  2.8      Amendment No. 1 dated September 19, 1997, to Stock Purchase and Sale
           Agreement dated May 12, 1997, by and between the Registrant and
           Thomas R. Eurich, Michael J. Krivitzky, Thomas J. McEnhill, and Bruce
           M. Bourdon (filed as Exhibit 2.5 to The Randers Group Incorporated's
           Annual Report on Form 10-K for the fiscal year ended April 4, 1998
           [File No. 0-18095] and incorporated herein by reference).

  2.9      Letter of Intent dated May 12, 1997, by and between the Registrant
           and The Randers Group Incorporated (filed as Exhibit (v) to Amendment
           No. 3 to Schedule 13D filed by Thermo Electron Corporation and the
           Registrant on May 13, 1997, and incorporated herein by reference).

  2.10     Stock Purchase Agreement entered on September 19, 1997, by and between the
           Registrant and The Randers Group Incorporated (filed as Exhibit (vii)
           to Amendment No. 4 to Schedule 13D filed by Thermo Electron
           Corporation and the Registrant on October 3, 1997, and incorporated
           herein by reference).

                                       17
<PAGE>


Exhibit
Number     Description of Exhibit

  2.11     Amendment No. 1 dated as of April 4, 1998, to Stock Purchase
           Agreement entered on September 19, 1997, by and between the
           Registrant and The Randers Group Incorporated (filed as Exhibit 2.8
           to The Randers Killam Group Incorporated's Annual Report on Form 10-K
           for the fiscal year ended April 4, 1998 [File No. 0-18095] and
           incorporated herein by reference).

  2.12     Agreement by and among the Registrant, The Randers Group
           Incorporated, Thomas R. Eurich, Michael J. Krivitzky, Thomas J.
           McEnhill, Bruce M. Bourdon, and David A. Wiegerink (filed as Exhibit
           10 to The Randers Group Incorporated's Current Report on Form 8-K
           dated October 3, 1997 [File No. 0-18095] and incorporated herein by
           reference).

  3.1      Restated Certificate of Incorporation, as amended (filed as Exhibit
           99 to the Registrant's Registration Statement on Form S-2 [Reg. No.
           333-02269] and incorporated herein by reference).

  3.2      Bylaws of the Registrant (filed as Exhibit 3(b) to the Registrant's
           Annual Report on Form 10-K for the fiscal year ended April 2, 1988
           [File No. 1-9549] and incorporated herein by reference).

  4.1      Fiscal Agency Agreement dated as of May 2, 1996, among the
           Registrant, Thermo Electron Corporation, and Chemical Bank, as Fiscal
           Agent (filed as Exhibit 4.2 to the Registrant's Annual Report on Form
           10-K for the fiscal year ended March 30, 1996 [File No. 1-9549] and
           incorporated herein by reference).

  4.2      Fiscal Agency Agreement dated as of May 5, 1995, among Thermo
           Remediation Inc., Thermo Electron Corporation, and Chemical Bank, as
           fiscal agent (filed as Exhibit 4.1 to Thermo Remediation Inc.'s
           Annual Report on Form 10-K for the fiscal year ended April 4, 1998
           [File No. 1-12636] and incorporated herein by reference).

           The Registrant hereby agrees, pursuant to Item 601(b)(4)(iii) (A) of
           Regulation S-K, to furnish to the Commission, upon request, a copy of
           each other instrument with respect to other long-term debt of the
           Company or its subsidiaries.

 10.1      Thermo Electron Corporate Charter as amended and restated effective
           January 3, 1993 (filed as Exhibit 10(a) to the Registrant's Annual
           Report on Form 10-K for the fiscal year ended April 3, 1993 [File No.
           1-9549] and incorporated herein by reference).

 10.2      Amended and Restated Corporate Services Agreement dated January 3,
           1993, between Thermo Electron Corporation and the Registrant (filed
           as Exhibit 10(b) to the Registrant's Annual Report on Form 10-K for
           the fiscal year ended April 3, 1993 [File No. 1-9549] and
           incorporated herein by reference).

 10.3      Agreement of Lease dated December 31, 1985, between Claridge
           Properties Ltd. and Thermo Electron Corporation (filed as
           Exhibit 10(c) to the Registrant's Registration Statement on
           Form S-1 [Reg. No. 33-6763] and incorporated herein by
           reference).

 10.4      Assignment of Lease dated December 31, 1985, between Thermo
           Electron Corporation and TMO, Inc. (filed as Exhibit 10(d) to
           the Registrant's Registration Statement on Form S-1 [Reg. No.
           33-6763] and incorporated herein by reference).

                                       18
<PAGE>

Exhibit
Number     Description of Exhibit

 10.5      Sublease dated March 30, 1986, between TMO, Inc. and
           Holcroft/Loftus, Inc. (filed as Exhibit 10(e) to the
           Registrant's Registration Statement on Form S-1 [Reg. No.
           33-6763] and incorporated herein by reference).

 10.6      Lease Amending Agreement dated January 1, 1995, between Claridge
           Properties Ltd., Thermo Electron Corporation, and TMO, Inc. (filed as
           Exhibit 10.6 to the Registrant's Annual Report on Form 10-K for the
           fiscal year ended April 1, 1995 [File No.
           1-9549] and incorporated by reference).

 10.7      Second Amendment to Sublease dated as of October 10, 1997, between
           the Registrant and TMO, Inc. (filed as Exhibit 2.5 to the
           Registrant's Current Report on Form 8-K dated October 10, 1997 [File
           No. 1-9549] and incorporated herein by reference).

 10.8      Sublease dated as of October 10, 1997, between the Registrant and
           Holcroft L.L.C. (filed as Exhibit 2.6 to the Registrant's Current
           Report on Form 8-K dated October 10, 1997 [File No. 1-9549] and
           incorporated herein by reference).

 10.9      Exclusive License and Marketing Agreement dated March 22, 1990, among
           TPS Technologies Inc., Holcroft Inc., and Thermo Soil Recyclers Inc.
           (filed as Exhibit 10(q) to the Registrant's Annual Report on Form
           10-K for the fiscal year ended March 31, 1990 [File No. 1-9549] and
           incorporated herein by reference).

 10.10     Form of Indemnification Agreement with Directors and Officers (filed
           as Exhibit 10(k) to the Registrant's Annual Report on Form 10-K for
           the fiscal year ended March 30, 1991 [File No. 1-9549] and
           incorporated herein by reference).

 10.11     Development Agreement dated September 15, 1991, between Thermo
           Electron Corporation and the Registrant (filed as Exhibit 10(l) to
           the Registrant's Quarterly Report on Form 10-Q for the fiscal quarter
           ended September 28, 1991 [File No. 1-9549] and incorporated herein by
           reference).

 10.12     Amended and Restated Development Agreement dated January 2, 1992,
           between Thermo Electron Corporation and the Registrant (filed as
           Exhibit 10(m) to the Registrant's Annual Report on Form 10-K for the
           fiscal year ended March 28, 1992 [File No. 1-9549] and incorporated
           herein by reference).

 10.13     Asset Transfer Agreement dated as of October 1, 1993, among the
           Registrant, TPS Technologies Inc., and Thermo Remediation Inc.
           (filed as Exhibit 2.3 to Thermo Remediation Inc.'s Registration
           Statement on Form S-1 [Reg. No. 33-70544] and incorporated
           herein by reference).

 10.14     Exclusive License Agreement dated as of October 1, 1993, among
           the Registrant, TPS Technologies Inc., and Thermo Remediation
           Inc. (filed as Exhibit 2.4 to Thermo Remediation Inc.'s
           Registration Statement on Form S-1 [Reg. No. 33-70544] and
           incorporated herein by reference).

 10.15     Non-Competition and Non-Disclosure Agreement dated as of
           October 1, 1993, among the Registrant, TPS Technologies Inc.'s,
           and Thermo Remediation Inc. (filed as Exhibit 2.5 to Thermo
           Remediation Inc.'s Registration Statement on Form S-1 [Reg. No.
           33-70544] and incorporated herein by reference).

 10.16     Tax Allocation Agreement dated as of June 1, 1992, between the
           Registrant and Thermo Remediation Inc. (filed as Exhibit 10.3
           to Thermo Remediation Inc.'s Registration Statement on Form S-1
           [Reg. No. 33-70544] and incorporated herein by reference).

                                       19
<PAGE>

Exhibit
Number     Description of Exhibit

 10.17     Agreement of Partnership dated May 16, 1994, among Terra Tech Labs
           Inc. (a wholly owned subsidiary of the Registrant) and Eberline
           Analytical Corporation, Skinner & Sherman, Inc., TMA/NORCAL Inc.,
           Normandeau Associates Inc., Bettigole Andrews & Clark Inc., Fellows,
           Read & Associates Inc., and Thermo Consulting Engineers Inc. (each a
           wholly owned subsidiary of Thermo Instrument Systems Inc.; filed as
           Exhibit 1 to the Registrant's Current Report on Form 8-K relating to
           the events occurring on May 16, 1994 [File No. 1-9549] and
           incorporated herein by reference).

 10.18     Promissory Note dated May 16, 1994, issued by the Registrant to
           Thermo Electron Corporation (filed as Exhibit 2 to the Registrant's
           Current Report on Form 8-K relating to the events occurring on May
           16, 1994 [File No. 1-9549] and incorporated herein by reference).

 10.19     Agreement of Dissolution of Partnership dated May 9, 1995, among
           Thermo Terra Tech (the Partnership), Terra Tech Labs, Inc. (a wholly
           owned subsidiary of the Registrant) and Eberline Analytical
           Corporation, Skinner & Sherman, Inc., TMA/NORCAL Inc., Normandeau
           Associates Inc., Bettigole Andrews & Clark Inc., Fellows, Read &
           Associates Inc., and Thermo Consulting Engineers Inc. (each a wholly
           owned subsidiary of Thermo Instrument Systems Inc.; filed as Exhibit
           2.1 to the Registrant's Current Report on Form 8-K relating to the
           events occurring on May 9, 1995 [File No. 1-9549] and incorporated
           herein by reference).

 10.20     Stock Purchase Agreement dated May 9, 1995, between the Registrant
           and Thermo Instrument Systems Inc. (filed as Exhibit 2.2 to the
           Registrant's Current Report on Form 8-K relating to the events
           occurring on May 9, 1995 [File No. 1-9549] and incorporated herein by
           reference).

 10.21     Note dated May 17, 1995, from the Registrant to Thermo Electron
           Corporation (filed as Exhibit 2.3 to the Registrant's Current Report
           on Form 8-K relating to the events occurring on May 9, 1995 [File No.
           1-9549] and incorporated herein by reference).

 10.22     Stock Purchase and Note Issuance Agreement dated as of November
           22, 1993, between the Registrant and Thermo Remediation Inc.
           (filed as Exhibit 10.11 to Thermo Remediation Inc.'s
           Registration Statement on Form S-1 [Reg. No. 33-70544] and
           incorporated herein by reference).

 10.23     $2,650,000 principal amount Subordinated Convertible Note dated as of
           November 22, 1993, made by Thermo Remediation Inc., issued to the
           Registrant (filed as Exhibit 10.12 to Thermo Remediation Inc.'s
           Registration Statement on Form S-1 [Reg. No. 33-70544] and
           incorporated herein by reference).

 10.24     Stock Purchase and Sale Agreement made and entered into on
           February 6, 1995, to be effective as of January 29, 1995, by
           and between Nord Est S.A., the Registrant, and Emil C. Herkert,
           Kenneth L. Zippler, Franklin O. Williamson, Jr., Fletcher N.
           Platt, Jr., Eugene J. Destefano, Meint Olthof, and Stanley P.
           Kaltnecker, Jr. (filed as Exhibit 1 to the Registrant's Current
           Report on Form 8-K relating to the events occurring on February
           6, 1995 [File No. 1-9549] and incorporated herein by reference).

 10.25     Agreement and Plan of Merger dated as of June 28, 1995, by and among
           the Registrant, Eberline Acquisition Inc., Thermo Remediation Inc.,
           and Eberline Holdings Inc. (filed as Appendix B to Thermo Remediation
           Inc.'s Proxy Statement for the Annual Meeting held on December 13,
           1995 [File No. 1-12636] and  incorporated herein by reference).

                                       20
<PAGE>

Exhibit
Number     Description of Exhibit

 10.26     $28,000,000 Secured Promissory Note dated as of January 29, 1995,
           issued by the Registrant to Nord Est S.A. (filed as Exhibit 2 to the
           Registrant's Current Report on Form 8-K relating to the events
           occurring on February 6, 1995 [File No. 1-9549] and incorporated
           herein by reference).

 10.27     $38,000,000 Promissory Note dated as of February 21, 1995, issued by
           the Registrant to Thermo Electron Corporation (filed as Exhibit 3 to
           the Registrant's Current Report on Form 8-K relating to the events
           occurring on February 6, 1995 [File No. 1-9549] and incorporated
           herein by reference).

 10.28     Asset Purchase Agreement by and among Thermo Analytical Inc.
           (as Buyer); Lancaster Laboratories, Inc. and Clewmark Holdings
           (as Sellers); and Earl H. Hess, Anita F. Hess, Kenneth E. Hess,
           J. Wilson Hershey, and Carol D. Hess (as the principal owners
           of Sellers) (filed as Exhibit 1 to the Registrant's Current
           Report on Form 8-K relating to the events occurring on May 10,
           1995 [File No. 1-9549] and incorporated herein by reference).

 10.29     Agreement and Plan of Merger dated as of the first day of December
           1995, by and among Thermo Remediation Inc., TRI Acquisition Inc., and
           Remediation Technologies, Inc. (filed as Exhibit 2(a) to the
           Registrant's Current Report on Form 8-K relating to the events
           occurring on December 8, 1995 [File No. 1-9549] and incorporated
           herein by reference).

 10.30     Purchase and Sale Agreement dated as of December 20, 1994, by and
           among TPS Technologies Inc., TPST Soil Recyclers of Maryland Inc.,
           Rafich Corporation, Harry Ratrie, John C. Cyphers, and J. Thomas Hood
           (filed as Exhibit 1 to Thermo Remediation Inc.'s Current Report on
           Form 8-K for the events occurring on December 21, 1994 [File No.
           1-12636] and incorporated herein by reference).

 10.31     Stock Purchase Agreement entered into on March 29, 1995, by and among
           Stalt Holding, B.V., Beheersmaatschappij J. Amerika N.V., A.J. Van
           Es, J.B. Van Es and D.A. Slager, and the Registrant (filed as Exhibit
           1 to the Registrant's Current Report on Form 8-K relating to the
           events occurring on March 29, 1995 [File No. 1-9549] and incorporated
           herein by reference).

 10.32     Thermo TerraTech Inc. - The Randers Group Incorporated Nonqualified
           Stock Option Plan (filed as Exhibit 10.1 to the Registrant's
           Quarterly Report on Form 10-Q for the quarter ended January 3, 1998
           [File No. 1-9549] and incorporated herein by reference).

 10.33     Incentive Stock Option Plan of the Registrant (filed as Exhibit 10(h)
           to the Registrant's Registration Statement on Form S-1 [Reg. No.
           33-6763] and incorporated herein by reference). (Maximum number of
           shares issuable in the aggregate under this plan and the Registrant's
           Nonqualified Stock Option Plan is 1,850,000 shares, after adjustment
           to reflect share increases approved in 1987, 1989, and 1992, 6-for-5
           stock splits effected in July 1988 and March 1989, and 3-for-2 stock
           split effected in September 1989.)

 10.34     Nonqualified Stock Option Plan of the Registrant (filed as Exhibit
           10(i) to the Registrant's Registration Statement on Form S-1 [Reg.
           No. 33-6763] and incorporated herein by reference). (Maximum number
           of shares issuable in the aggregate under this plan and the
           Registrant's Incentive Stock Option Plan is 1,850,000 shares, after
           adjustment to reflect share increases approved in 1987, 1989, and
           1992, 6-for-5 stock splits effected in July 1988 and March 1989, and
           3-for-2 stock split effected in September 1989.)

 10.35     Deferred Compensation Plan for Directors of the Registrant
           (filed as Exhibit 10(k) to the Registrant's Registration
           Statement on Form S-1 [Reg. No. 33-6763] and incorporated
           herein by reference).

                                       21
<PAGE>

Exhibit
Number     Description of Exhibit

 10.36     Equity Incentive Plan (filed as Exhibit 10.63 to Thermedics Inc.'s
           Annual Report on Form 10-K for the fiscal year ended January 1, 1994
           [File No. 1-9567] and incorporated herein by reference; maximum
           number of shares issuable is 1,750,000 shares, after adjustment to
           reflect share increase approved in 1994).

 10.37     Directors Stock Option Plan, as amended and restated effective
           January 1, 1995 (filed as Exhibit 10.39 to the Registrant's Annual
           Report on Form 10-K for the fiscal year ended April 1, 1995 [File No.
           1-9549] and incorporated herein by reference).

 10.38     Thermo TerraTech Inc. (formerly Thermo Process Systems Inc.) -
           Thermo Remediation Inc. Nonqualified Stock Option Plan (filed
           as Exhibit 10(l) to the Registrant's Quarterly Report on Form
           10-Q for the fiscal quarter ended January 1, 1994 [File No.
           1-9549] and incorporated herein by reference).

           In addition to the stock-based compensation plans of the Registrant,
           the executive officers of the Registrant may be granted awards under
           stock-based compensation plans of Thermo Electron for services
           rendered to the Registrant or to such affiliated corporations. The
           terms of such plans are substantially the same as those of the
           Registrant's Equity Incentive Plan.

 10.39     Restated Stock Holdings Assistance Plan and Form of Executive Loan
           (filed as Exhibit 10.42 to the Registrant's Annual Report on Form
           10-K for the fiscal year ended March 29, 1997 [File No. 1-9549] and
           incorporated herein by reference).

 10.40     Deferred Compensation Agreement dated September 16, 1996, between Elson T.
           Killam Associates Inc. and Emil C. Herkert (filed as Exhibit 10.1 to
           the Registrant's Quarterly Report on Form 10-Q for the fiscal quarter
           ended July 4, 1998 [File No. 1-9549] and incorporated herein by
           reference).

 10.41     Addendum dated 1990, to Deferred Compensation Agreement dated September 16,
           1986, between Elson T. Killam Associates Inc. and Emil C. Herkert
           (filed as Exhibit 10.2 to the Registrant's Quarterly Report on Form
           10-Q for the fiscal quarter ended July 4, 1998 [File No. 1-9549] and
           incorporated herein by reference).

 10.42     Amendment No. 1, dated April 27, 1990, to Deferred Compensation Agreement
           dated September 16, 1986, between Elson T. Killam Associates Inc.
           and Emil C. Herkert (filed as Exhibit 10.3 to the Registrant's Quarterly
           Report on Form 10-Q for the fiscal quarter ended July 4, 1998
           [File No. 1-9549] and incorporated herein by reference).

 10.43     Master Cash Management, Guarantee Reimbursement, and Loan Agreement dated as
           of June 1, 1999, between the Registrant and Thermo Electron
           Corporation.

 10.44     Master Cash Management, Guarantee Reimbursement, and Loan Agreement dated as
           of June 1, 1999, between ThermoRetec Corporation and Thermo Electron
           Corporation (filed as Exhibit 10.17 to ThermoRetec Corporation's
           Annual Report on Form 10-K for the fiscal year ended April 3, 1999
           [File No. 1-12636] and incorporated herein by reference).

 10.45     Master Cash Management, Guarantee Reimbursement, and Loan Agreement dated as
           of June 1, 1999, between The Randers Killam Group Inc. and Thermo
           Electron Corporation (filed as Exhibit 10.18 to The Randers Killam
           Group Inc.'s Annual Report on Form 10-K for the fiscal year ended
           April 3, 1999 [File No. 0-18095] and incorporated herein by
           reference).

                                       22
<PAGE>


Exhibit
Number     Description of Exhibit

 13        Annual Report to Shareholders for the fiscal year ended April 3, 1999
           (only those portions incorporated herein by reference).

 21        Subsidiaries of the Registrant.

 23        Consent of Arthur Andersen LLP.

 27        Financial Data Schedule.
</TABLE>